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The study aimed to explore the ultrastructure of the donkeys' palatine tonsils. Palatine tonsils of five male donkeys (5 years old) were investigated macroscopically and microscopically. The tonsils appeared as a dome shape with slight elevation and a circular opening on the surface of the oropharynx. The central tonsillar crypt appeared on the medial side of the palate-pharyngeal folds and the floor of the oropharynx. The external surface of the palatine tonsil had different sizes of mucosal folds, some grooves directed to drainage at the tonsillar opening, and the tonsil crypt opening was a crescentic or irregular oval shape. The outer surface was covered by stratified squamous epithelium and modified to be reticular epithelium invaded by lymphocytes in the crypt called lympho-epithelium. The tonsil crypt had aggregated lymphoid nodules, and the cryptal epithelium has surrounded by diffused lymphocytes and hassles corpuscles-like structures. The lymphocytes infiltrated into different layers of the cryptal epithelium and transformed into reticular or lympho-epithelium. The organized lymphoid nodules were primary and secondary, and the secondary ones had a light germinal center. The interfollicular area had many high endothelial venules and blood capillaries. The endothelial venules were lined by simple cuboidal epithelium and had lymphocytes. The blood capillaries had red blood cells and neutrophils. The tonsil was surrounded incompletely by a connective tissue capsule with mucous glands under that capsule. In conclusion, the epithelial lymphocyte infiltration, crypt epithelium, lymphoid nodules, and intra-follicular area of the donkey's palatine tonsils indicate the humoral and cell-mediated immunological process., (© 2022 Wiley Periodicals LLC.)

This study aimed to describe the morphology, expression of IgA and IgG in adult yak tonsils. The 12 clinically healthy yak tonsils [3- to 6-year old, n = 12] were examined for morphology using light, and transmission electron microscopes. Expression of IgA and IgG was measured by qRT-PCR, ELISA, and immunohistochemistry. The results showed that the palatine tonsil, the tonsil of the soft palate, and the lingual tonsil were oropharyngeal tonsils. The stratified squamous epithelia covering them had a thick underlying layer of connective tissue and their crypts were heavily infiltrated by lymphocytes. The pharyngeal tonsil and the tubal tonsil were nasopharyngeal tonsils. The epithelia of them was predominantly pseudostratified columnar ciliary epithelium, which were loosely arranged with a number of desmosomes or intermediate junctions variably connecting them. The expression levels of IgA and IgG mRNA and protein from high to low was in the pharyngeal tonsil, palatine tonsil, tonsil of the soft palate, lingual tonsil, and tubal tonsil, respectively. Interestingly, the expression of IgG was very significantly higher than that of IgA in yak tonsils (P < 0.01). Both the IgA and IgG ASCs were distributed in the subepithelial areas of the non-reticular crypt epithelium, especially areas of pseudostratified columnar ciliary epithelium, the reticular crypt epithelium, lymphoid follicles, interfollicular areas, and with some of the positive cells aggregating around the glands. The results indicated that the tonsils were not only typical secondary lymphoid organs but also lymphoepithelial structures. IgG could be a significant component of mucosal immune responses in yak tonsils. Anat Rec, 302:999-1009, 2019. © 2018 Wiley Periodicals, Inc., (© 2018 Wiley Periodicals, Inc.)

This study describes the mucosa-associated lymphoid tissue (MALT) in odontocetes from the Brazilian coast and freshwater systems. Seven species were evaluated and tissue samples were analyzed by light, scanning and transmission electron microscopy, and immunohistochemistry. Laryngeal tonsil was a palpable oval mass located in the larynx, composed of a lymphoepithelial complex. Dense collections of lymphocytes were found in the skin of male fetus and calf. Clusters of lymphoid tissue were found in the uterine cervix of a reproductively active juvenile female and along the pulmonary artery of an adult female. Lymphoid tissues associated with the gastrointestinal tract were characterized by diffusely arranged or organized lymphocytes. The anal tonsil was composed of an aggregate of lymphoid tissue occurring exclusively in the anal canal, being composed of squamous epithelium branches. MALT was present in different tissues and organic systems of cetaceans, providing constant protection against mucosal pathogens present in their environment., (© 2016 Wiley Periodicals, Inc.)

The human palatine tonsils represent a mucosa-associated lymphoid tissue with a significant function in mucosal protection against alimentary and airborne pathogens. The ultrastructure of different morphological compartments in the human palatine tonsil was studied in eighteen tonsils obtained from the patients who had undergone elective tonsillectomy due to chronic tonsillitis. The tonsillar specimens were analyzed by scanning and transmission electron microscopy. The results showed the presence of tight junctions between superficial epithelial cells of the oropharyngeal tonsillar surface. The crypt epithelium is a sponge-like structure infiltrated by non-epithelial cells, mostly lymphocytes, and is characterized by the presence of small pores - microcrypts occupied by large microvillus cells and/or lymphocytes. Antigen-presenting Langerhans cells with typical intracytoplasmic Birbeck granules were also found in the crypt epithelium. The lymphoid follicles are composed of lymphocytes and two types of non-lymphoid follicular cells: small fibroblast-like cells and large cells, morphologically consistent with antigen-bearing follicular dendritic cells or macrophages. The interfollicular areas consisted of a dense network of reticular cells and reticular fibers; many lymphocytes were interspersed between the reticular fibers. In addition to arterioles and high endothelial venules in the interfollicular lymphoid tissue, some fenestrated capillaries were seen intraepithelially and subepithelially. The complex ultrastructure of the human palatine tonsil provides a microenvironment necessary for antigen uptake, antigen processing and immune response.

Conclusion: The results of the study suggest that biofilms play a causative role in recurrent tonsillitis., Objective: To analyze the association between tonsillar biofilms and recurrent tonsillitis., Methods: The recurrent tonsillitis group comprised patients with a history of at least five episodes of tonsillitis per year over the previous 2 years. The control group comprised volunteers scheduled for laryngeal microsurgery with no history of tonsillitis over the previous 2 years. Between October 2009 and August 2010, specimens were obtained from 20 patients with recurrent tonsillitis and 20 volunteers (controls). Scanning electron microscopy (SEM) was used to confirm the presence of biofilms. Biofilms were graded at a magnification of ×500 by SEM and classified into five grades. The percentages of subjects affected and biofilm grades were compared between the recurrent tonsillitis and control groups., Results: The two groups were matched for age and sex. SEM revealed that biofilms were significantly more prevalent in the recurrent tonsillitis group than in the control group. Furthermore, the biofilms in the recurrent tonsillitis group were of significantly higher grade than those in the control group.

The development of a broad repertoire of T cells, which is essential for effective immune function, occurs in the thymus. Although some data suggest that T cell development can occur extrathymically, many researchers remain skeptical that extrathymic T cell development has an important role in generating the T cell repertoire in healthy individuals. However, it may be important in the setting of poor thymic function or congenital deficit and in the context of autoimmunity, cancer, or regenerative medicine. Here, we report evidence that a stepwise program of T cell development occurs within the human tonsil. We identified 5 tonsillar T cell developmental intermediates: (a) CD34⁺CD38dimLin⁻ cells, which resemble multipotent progenitors in the bone marrow and thymus; (b) more mature CD34⁺CD38brightLin⁻ cells; (c) CD34⁺CD1a⁺CD11c⁻ cells, which resemble committed T cell lineage precursors in the thymus; (d) CD34⁻CD1a⁺CD3⁻CD11c⁻ cells, which resemble CD4⁺CD8⁺ double-positive T cells in the thymus; and (e) CD34⁻CD1a⁺CD3⁺CD11c⁻ cells. The phenotype of each subset closely resembled that of its thymic counterpart. The last 4 populations expressed RAG1 and PTCRA, genes required for TCR rearrangement, and all 5 subsets were capable of ex vivo T cell differentiation. TdT⁺ cells found within the tonsillar fibrous scaffold expressed CD34 and/or CD1a, indicating that this distinct anatomic region contributes to pre-T cell development, as does the subcapsular region of the thymus. Thus, we provide evidence of a role for the human tonsil in a comprehensive program of extrathymic T cell development.

The histology and ultrastructure of porcine tonsils were studied. The porcine tonsils were lymphoepithelial organs situated at the opening of both the digestive and respiratory tracts. The tonsil of the soft palate in the oropharyngeal tract and the paraepiglottic tonsil in the laryngopharynx were mainly consisted of secondary lymphoid follicles encapsulated by connective tissue. The stratified squamous epithelia covering the tonsils and their crypts were frequently heavily infiltrated by lymphoid cells. The pharyngeal and tubal tonsils (TT) were situated in the nasopharyngeal tract. The cells of the pseudostratified columnar epithelia of the pharyngeal and TT were loosely connected, with large intercellular space. They consisted of scattered lymphoid follicles, aggregations of lymphoid cells and diffuse lymphoid tissues. Many high endothelial venules, specialized for the diapedesis of lymphoid cells into the tonsillar tissue, were detected in the four porcine tonsils. Therefore, the overall structures of the tonsils (the tonsil of the soft palate, the paraepiglottic tonsil, the pharyngeal and the TT) reflect their immune functionality in the oral and intranasal immunity., (Copyright © 2011 Wiley Periodicals, Inc.)

Current methods for sustainable control of avian coccidiosis, whether by prophylactic medication or parasite vaccination, are suboptimal. In this study, we describe an alternative immunization strategy against Eimeria tenella infection using parasite antigen (Ag)-loaded dendritic cells (DCs), or their derived exosomes, in the absence of free Ag. CD45(+) intestinal DCs were isolated from E. tenella-infected chickens and loaded ex vivo with an extract of sporozoites as parasite Ag. Extracellular vesicles purified from the Ag-pulsed DCs expressed surface proteins associated with DC-derived exosomes, including major histocompatibility complex proteins (MHC I and MHC II), CD80, flotillin, and heat shock protein (HSP70). Following intramuscular immunization of chickens with Ag-pulsed DCs or Ag-pulsed DC-derived exosomes, Ag-containing cells were observed diffusely localized in the lymphoid tissue and concentrated in germinal centers of caecal tonsils, and restricted to germinal centers (GC) in the spleen. Chickens immunized with pulsed DCs or exosomes exhibited (a) higher numbers of caecal tonsil and spleen cells expressing IgG and/or IgA antibodies that were reactive with E. tenella Ag, (b) greater numbers of IL-2-, IL-16-, and IFN-γ-producing cells, and (c) higher E. tenella Ag-driven cell proliferation, compared with chickens immunized with Ag in the absence of DCs or exosomes. Chickens immunized with Ag-pulsed DCs or Ag-pulsed DC-derived exosomes and subsequently given a live E. tenella challenge infection at 10d post-immunization displayed (a) increased body weight gains, (b) decreased feed conversion ratios, (c) reduced fecal oocyst shedding, (d) diminished intestinal lesions, and (e) lower mortality, compared with animals given Ag alone. This is the first demonstration of Ag-specific protective immunity against avian coccidiosis using parasite Ag-loaded DCs or DC-derived exosomes., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

As solid morphological knowledge of ovine tonsillar epithelia might contribute to a better understanding of the pathogenesis of several diseases including prion diseases, the epithelia of all tonsils of 7 one-year-old Texel sheep were examined using scanning and transmission electron microscopy. Major parts of the pharyngeal and tubal tonsils were covered by pseudostratified columnar ciliated epithelia that were interrupted by patches of epithelium containing cells with densely packed microfolds or microvilli, and cells with both microvilli and cilia. Smaller parts were covered by either flattened polygonal cells with densely packed microvilli or microfolds, squamous epithelial cells, or patches of reticular epithelium. The palatine and paraepiglottic tonsils were mainly lined by squamous epithelial cells with apical microplicae or short knobs. Additionally, regions of reticular epithelium containing epithelial cells with apical microvilli were seen. The lingual tonsil was uniformly covered by a keratinized squamous epithelium and devoid of microvillous cells and patches of reticular epithelium. The rostral half of the tonsil of the soft palate was lined by a pseudostratified columnar ciliated epithelium with characteristics of the pharyngeal and tubal tonsils. The epithelium of the caudal part resembled the epithelia of the palatine and paraepiglottic tonsils. Putative M cells, mainly characterized by apical microvilli or microfolds and a close association with lymphoid cells, seem manifestly present on the nasopharyngeal tonsils. The reticular epithelium of the palatine and paraepiglottic tonsils also harbor cells with small apical microvilli. The exact nature of these presumptive M cells should, however, be elucidated in functional studies.

Air pollution by suspended particles has become a worldwide health problem. The main sources of these particles are fossils and additives combustion. Mn enters the body through inhalation, but part of the particles accesses contact with tongue's posterior surface where lingual tonsils and lingual papillae are placed. We decided to explore in a mouse model, the impact that the deposit of inhaled Mn has on the tongue's surface. Atrophy of the lingual tonsil, filiform papillae, as well as the swelling of taste buds in fungiform papillae, were the predominant changes. Ferropenic anemia is associated with the changes described and could be related to the interference of Mn in iron metabolism and riboflavin absorption. More research should be done to explore the participation of suspended particles trapped in the oral cavity in toxicology of Mn or other inhaled pollutants.

The development of heat-induced antigen (epitope) retrieval (HIER) technologies has led to dramatic improvements in our ability to detect antigens in formalin fixed, archival tissues. Paradoxically, wet heat treatment at temperatures greater than 95 degrees C in appropriate buffer solutions can reconstitute the antigenicity of many proteins that have been rendered nonreactive during the fixation and paraffin embedding process, which heretofore could only be identified in fresh or frozen tissues. The reason for this effect is unclear, but it has been suggested that the vigorous heat treatment partially reverses or disrupts the aldehyde cross-links occurring in proteins during formalin fixation and restores the original conformation of antigenic epitopes. The great success of antigen/epitope retrieval technologies further emphasizes the importance of preanalytical steps in immunohistochemistry. Over the past several years, since this technology was first reported, there have been numerous modifications to the original formulation. It is the purpose of this chapter to discuss the critical issues required for optimal HIER and to provide guidelines for the use of popular HIER buffers and heating devices used for routine immunohistochemical detection.

Tonsils form a first line of defense against foreign antigens and are also a route of entry and a replication site for some pathogens. The palatine tonsils are the largest of all the tonsils. Despite their general importance, little is known about the microanatomy of the palatine tonsils of the one-humped camel. Palatine tonsils of 10 clinically healthy male camels were obtained directly after slaughtering for human consumption. The tonsils were examined macroscopically and by light, scanning, and transmission electron microscopy. Palatine tonsils had the unique form of several spherical macroscopic nodules protruding into the pharyngeal lumen. These spherical masses were numerous and close together in the lateral oropharyngeal wall, with a few solitary nodules in the dorsal wall. Each nodule had one or two apical openings to crypts, and was enclosed by an incomplete connective tissue capsule and covered apically with stratified squamous keratinized epithelium. The tonsillar crypt was lined with stratified squamous non keratinized epithelium. Several lymphocytes infiltrated the epithelial layer, forming patches of reticular epithelium. Lymphoid follicles with obvious germinal centers extended under the epithelial surface. Diffusely localized lymphocytes were seen in the interfollicular region. High endothelial venules, dendritic cells, macrophages, and plasma cells were observed among these lymphocytes. The unique arrangement of palatine tonsils in separate units with individual crypts results in a very large surface exposed to antigen and indicates a significant immunological role of palatine tonsils in the camel., ((c) 2009 Wiley-Liss, Inc.)

The paired palatine tonsils, located at the junction of the nasopharynx and oropharynx, are ideally positioned to sample antigens entering through the nasal cavity or oral cavity. Entering antigens will first contact tonsilar epithelium. To better understand the cellular composition of this important epithelial layer, palatine tonsils were collected from six, 7-month-old calves and examined by light microscopy, immunohistochemistry and electron microscopy. Morphometric analysis showed that epithelium overlying lymphoid follicles (reticular epithelium) contained more B-cells, CD4+, CD8+, CD11c+, CD172a+ and gamma/delta TCR+ cells than non-reticular epithelium, with B-cells, CD4+ cells and CD11c+ cells being most numerous. Scanning and transmission electron microscopy of reticular epithelium identified an interrupted basement membrane and vascular elements within the epithelium, as well as cells with characteristics morphologically consistent with cells identified as M-cells in other species. Bovine palatine tonsilar reticular epithelium contains key immune cells, as well as potential M-cell-like cells; elements essential for antigen uptake, antigen processing and initiation of immune responses.

The purpose of this study was to characterize the ultrastructure of lymphoid tissue from HIV/AIDS patients and to evaluate it as a reservoir and source of HIV. HIV has been demonstrated in lymph nodes and tonsils and adenoids, by immunohistochemistry (IHC), in situ hybridization (ISH), and transmission electron microscopy (TEM), to be associated with germinal center (GC) follicular dendritic cells (FDC). The presence of HIV in the larger gastrointestinal tract-associated lymphoid tissue (GALT) has been much less studied. Whether FDC themselves are productively infected by HIV in any of the lymphoid sites is controversial. Lymph nodes, tonsils, and gastrointestinal biopsies were fixed in neutral buffered glutaraldehyde and prepared for TEM. Mature HIV particles were abundant in GC of hyperplastic lymph nodes, tonsils, and the GALT. They were enmeshed within an electron-dense matrix associated with an all-encompassing branching FDC network of processes. HIV particles were seen budding from both FDC and lymphocytes. The greatest numbers of particles were seen in hyperplastic lymphoid tissue from untreated individuals and in lymph nodes co-infected with opportunistic organisms, such as Mycobacterium avium complex. In addition to HIV, unidentifiable "particles" of varying sizes, possibly including other viruses, were regularly seen in association with FDC. Ultrastructural study graphically demonstrated the abundance of HIV particles associated with the complex FDC network of hyperplastic lymph nodes, tonsils, and GALT. HIV was shown to productively infect FDC, as well as lymphocytes.

The localization of the bovine lingual tonsil is described as a prerequisite for the removal of specified risk material from the tongue meat in order to restrict the risk arising from bovine spongiform encephalopathy (BSE) to public health. The major part of this tonsil can be located macroscopically by the openings of its follicular crypts at the root of tongue. This part consists of organized aggregations of lymph nodules. Additional solitary primary lymph nodules and diffuse accumulations of lymphocytes are macroscopically invisible but are bilaterally present in the area extending 2 cm caudal to 3 cm rostral to the last vallate papillae. By sectioning the tongue 3 cm rostral to the last vallate papillae, undermining the lingual mucosa to the level of these papillae and making a transverse cut towards the lingual process of the basihyoid bone, the greater part of the lingual tonsil can efficiently be removed. Finally, immunohistochemical staining demonstrated the presence of T and B lymphocytes, suggesting that the bovine lingual tonsil can be considered as a site where an immune response can be induced.

Naive and central memory CD8 T cells use CCR7 to recirculate through T cell zones of secondary lymphoid organs where they can encounter antigen. Here we describe a subset of human CD8 T cells expressing CXCR5 which enables homing in response to CXCL13 produced within B cell follicles. CXCR5+ CD8 T cells were found in tonsil B cell follicles, and isolated cells migrated towards CXCL13 in vitro. They expressed CD27, CD28, CD45RO, CD69, and were CD7low, and produced IFN-gamma and granzyme A but lacked perforin, a functional profile suggesting that these cells are early effector memory cells in the context of contemporary T cell differentiation models. Receptors important in the interaction with B cells, including CD70, OX40 and ICOS, were induced upon activation, and CXCR5+ CD8 T cells could to some extent support survival and IgG production in tonsil B cells. Furthermore, CXCR5+ CD8 T cells expressed CCR5 but no CCR7, suggesting a migration pattern distinct from that of follicular CD4 T cells. The finding that a subset of early effector memory CD8 T cells use CXCR5 to locate to B cell follicles indicates that MHC class I-restricted CD8 T cells are part of the follicular T cell population.

The detection of genetic abnormalities (eg, translocations, amplifications) in paraffin-embedded samples by the fluorescence in situ hybridization (FISH) technique is usually performed on tissue sections. FISH analysis of nuclei extracted from paraffin-embedded samples is also possible, but the technique is not widely used, principally because of the extra labor involved and the loss of information on tissue architecture. In this article, we report that nuclei extracted from paraffin-embedded tissue often retain at least part of the surrounding cytoplasm. Consequently, immunocytochemical labeling for a range of cellular markers (eg, of lineage or proliferation) can be performed in combination with FISH labeling, allowing specific cell populations to be analyzed for genetic abnormalities. These cell preparations are largely free of the problems associated with tissue sections (eg, truncation artifact, signals in different focal planes) so that interpretation is easy and numerical chromosomal abnormalities are readily assessed. Cells isolated from paraffin sections can be stored in suspension so that arrays can be created as and when needed from a range of neoplasms for investigation by the immunoFISH technique (for example, for studying a new genetic abnormality). This procedure represents a novel methodology, which in some settings offers clear advantages over analysis of tissue sections.

Lymphoid organs are supplied by many nerve endings associated with different kinds of cells and macrophages. The role of these neuromediators on the release of locally active molecules is still unknown. Here we focused our attention on the expression of some neurotrophins (NTs), their high- and low-affinity receptors and several neurotransmitters in human palatine tonsils. Light and electron microscopy immunohistochemistry showed that human tonsillar samples were positive for all analyzed neurotrophins (NGF, BDNF and NT-3) and their high-affinity receptors (TrkA, TrkB and TrkC, respectively). All of these molecules were strongly expressed in macrophages whereas, in some patients, a weaker specific staining of lymphocytes and blood vessels was also found. The low-affinity receptor for NGF (p75) was always absent in the analysed samples. RT-PCR confirmed the occurrence of specific transcripts for NTs and their high-affinity receptors as well as the absence of mRNA for p75 protein. Also, specific immunoreactivity for neurotransmitters SP, VIP, CGRP, ChAT and nNOS was mainly expressed by macrophagic cells. These results suggest the presence of an extensive network of innervation in the human palatine tonsils which may play a role in the regulation of some immune functions as well as in the modulation of a possible functional scenario of interactions among different immune cellular subtypes.

Objective: To evaluate the expression of human glucocorticoid receptors (hGRs), such as hGR (4H2), hGR-alpha, and hGR-beta, in non-neoplastic lymphoid follicles and B cell type malignant lymphomas., Methods: The expression of hGRs in non-neoplastic lymphoid follicles and malignant lymphomas, including diffuse large cell lymphoma, mantle cell lymphoma, and follicular lymphoma, was examined immunohistochemically. HGR (4H2) expression was confirmed by double immunostaining of tissues and in isolated cells from tonsillar germinal centres, and by immunoelectronmicroscopy., Results: In secondary lymphoid follicles of any non-neoplastic diseases--such as chronic tonsillitis, reactive lymphadenitis, and Kimura's disease--the germinal centre cells often expressed hGR (4H2) and hGR-alpha. Double immunocytochemical staining of isolated germinal centre cells showed that the majority of hGR (4H2) positive cells were CD20 positive B cells, and that follicular dendritic cells also expressed hGR. Immunoelectronmicroscopy revealed the presence of nuclear hGR (4H2) in the binucleated follicular dendritic cells and germinal centre cells. The frequency of hGR (4H2) expression in diffuse large B cell lymphoma was higher, that in mantle cell lymphoma was lower, and that in follicular lymphoma was intermediate among the types of malignant lymphoma. The hGR (4H2) expression was less frequent in cases of grade I follicular lymphoma., Conclusions: There are differences in hGR expression between the germinal centre and the mantle zone in non-neoplastic lymphoid follicles, and differences of hGR (4H2) expression among the types of malignant lymphoma and grades of follicular lymphoma, which probably contribute to the different steroid sensitivities.

The tonsil of the soft palate was an oval, flat structure located centro-rostrally on the oral surface of the soft palate. Its stratified squamous non-keratinized epithelium was perforated by holes or small crypts the deeper parts of which were loosely spongiform inter-digitated with lymphoid tissue. These unusual features have not previously been reported in tonsils of any species. Crypts and reticulated epithelium as found in the lingual and palatine tonsils were not observed. Lectins showed varying affinities for specific layers of the epithelium. M cells were not observed. A few Langerhans cells were distributed among surface epithelial cells. Lymphoid tissue was arranged loosely and in isolated lymphoid follicles in the subepithelial lamina propria mucosae. Although IgA+ cells and macrophages were proportionately more numerous the amount of lymphoid tissue was much less than in the lingual and palatine tonsils. Most of the follicular germinal centres lacked a darkly stained corona. CD4 positive were more numerous than CD8+ lymphocytes and were distributed in the parafollicular and inter-follicular areas. Large clusters of mucus acini positive for glycogen, acidic and neutral mucopolysaccharides separated lymphoid tissue from deeply placed striated muscle. Only a few high endothelial venules were observed in the parafollicular and inter-follicular areas. These had relatively few vesiculo vacuolar or other organelles in their high endothelial cells and few lymphocytes attaching to their walls.

Sixty chickens were randomly divided into two groups to determine the effect of oral administration of probiotics on the intestinal mucosal immune response and ultrastructure of cecal tonsils. The first group (control) was fed with a basic diet without antibiotic or probiotics. The second group was fed with the same diet as the control, except they received drinking water with probiotics (4 x 10(9) cfu per chicken and day) from posthatch to day 3 of age. The probiotic preparation was composed of Bacillus subtilis Bs964, Candida utilis BKM-Y74 and Lactobacillus acidophilus LH1F. Intestinal fluid, Peyer's Patch and cecal tonsils were taken at day 1, 4, 7, 10 and 18 after administration of probiotics. The results showed: (i) Compared to the control, probiotics enhanced the content of following items: immunglobulin (Ig)A in the intestinal fluid at day 7 (p < 0.01), the IgG-forming cells at day 10 (p < 0.05), IgM-forming cells in the Peyer's Patch at day 7 (p < 0.05), IgA-forming cells at day 7-10 (p < 0.05), IgG-forming cells at day 7 (p < 0.05) and IgM-forming cells in cecal tonsils diffuse area at day 4-7 (p < 0.05). (ii) T lymphocytes in cecal tonsils were enhanced at day 7 (p < 0.01) after orally fed with probiotics. (iii) The density of microvilli and length of cecal tonsils increased after probiotics were administrated at day 3. With chicken ageing, the efficiency of probiotics would decrease. These results suggested that probiotics enhance intestinal mucosal immunity of chicken at the early age.

Background: Tobacco smoke is a well-known source of toxic, mutagenic and carcinogenic agents. The aim of the present preliminary study was to investigate the effects of cigarette smoking on lymphoid and non-lymphoid tonsillar tissue., Methods: The study group consisted of 12 smoker and 10 non-smoker patients complaining recurrent tonsillitis. Clinical data, histological findings and scanning electron microscopic analyses were considered. To the best of our knowledge, such an approach has not been previously adopted in a similar experimental model., Results: Smoker patients showed a longer history of recurrent tonsillitis, difficulties in clinical management and evident morphostructural changes than non-smokers., Conclusions: These preliminary results suggest a possible interference of cigarette smoking with the therapy response as well as a possible role of tobacco smoke in impairment of inflammatory response. Results are critically analysed and discussed. Literature data on this subject are reviewed.

The palatine tonsils of five young horses formed 10-12 cm elongated follicular structures extending from the root of the tongue on either side to the base of the epiglottis and lateral to the glossoepiglottic fold. The stratified squamous non-keratinized epithelium of the outer surface was modified into crypts as reticular epithelium by heavy infiltration of lymphoid cells from underlying lymphoid follicles. In places, lymphoid tissue reaching almost to the surface and with only one to two cell layers intact was identified as the lymphoepithelium. Langerhans cells with Birbeck granules were interspersed between epithelial cells. Lymphoid tissue organized in lymphoid follicles constituted the parenchyma of the palatine tonsil. CD4-positive cells were more numerous and CD8-positive lymphocytes less numerous compared with their distribution in the lingual tonsil. B cells and macrophages were also more numerous than in the lingual tonsil and lectins showed a different pattern of attachment. M cells were not observed. High endothelial venules with well-developed vesiculo-vacuolar organelle had structural evidence of transendothelial and interendothelial migration of lymphocytes. Striated muscles as seen in the deeper lamina propria mucosae of the lingual tonsil were absent. The immunohistological and ultrastructural characteristics of the equine palatine tonsil are similar to those of humans but differ from those of the lingual tonsil and are consistent with a role as an effector and inductor immunological organ.

The tubal tonsil of the horse surrounds the pharyngeal opening of the eustachian tube and is lined by pseudostratified columnar ciliated epithelium interspersed with areas of follicle-associated epithelium (FAE) heavily infiltrated by lymphocytes but devoid of goblet and ciliated cells. Scanning and transmission electron microscopy revealed microvillous cells and cells with features characteristic of M cells such as reduced microvilli or depressed bare surface, more numerous mitochondria, small vesicles and lysosomes, as well as vimentin filaments and epitopes specific for GS 1-B4 as previously seen in the nasopharyngeal tonsil. M cells were also identified in areas of respiratory epithelium not associated with lymphoid follicles and appeared to be the nasal mucosal counterparts of recently described intestinal villous M cells in the mouse. The underlying lymphoid tissue of the FAE was generally organized as solitary lymphoid follicles without germinal centres in contrast to the diffuse and large amount of organized lymphoid follicles with germinal centres that characterize the nasopharyngeal tonsil. CD8+ T and B-lymphocytes were much fewer than in the nasopharyngeal tonsil. High endothelial venules were mainly oriented towards the parafollicular area and contained much fewer endothelial pores and vesiculo-vacuolar organelles. Finally, scattered small clusters of mucus acini and striated muscles were other features that differentiated the tubal and nasopharyngeal tonsils.

The majority of newly acquired HIV infections are believed to occur following transmission of virus infectivity across mucosal surfaces, although many mechanistic details still remain unresolved. We have used human ex vivo organ cultures and primary cell populations to analyze the cellular and molecular basis for mucosal HIV transmission. By using human palatine tonsil from routine tonsillectomies and semen from HIV-positive donors, we have created an experimental equivalent to oral HIV transmission. HIV infection was readily transferred into tonsillar lymphocytes, but this transmission into lymphocytes was dramatically reduced when the exposed lymphocyte populations were protected by intact mucosal surfaces. In this study, we consider the impact that leukocyte activation and morphological aberrations in surface structure may have on susceptibility to primary HIV infection and introduce novel time-lapse confocal microscopy procedures that begin to reveal the dynamic complexity associated with cell-mediated HIV transmission.

The stratified squamous epithelium of the lingual tonsil of five young horses was infiltrated with CD4 and CD8 positive cells, which were very numerous in the crypt reticular epithelium along with macrophages and IgGb and IgA positive cells. Lymphoid follicles of the lamina propria mucosae consisted of a parafollicular area, corona and germinal centre. The parafollicular area was populated by large numbers of CD4 and CD8 positive lymphocytes as well as macrophages, inter-digitating cells, and a few B-lymphocytes. The germinal centre contained mainly IgGb and IgG(T) positive cells, plasma cells and small numbers of follicular dendritic cells, macrophages, CD4, CD8 and IgA positive cells. Some venules in the parafollicular and inter-follicular areas had features characteristic of high endothelial venules with irregular nuclei and cytoplasmic processes on the luminal surface. In addition to the normal cytoplasmic organelles, a novel vesiculo-vacuolar organelle was observed in small clusters toward the lateral, luminal and abluminal surfaces of these high endothelial venules. These vesiculo organelles along with their stomata and diaphragms, communicated with each other and with inter-endothelial clefts forming a structural basis for enhanced permeability and extravasation of macromolecules. The presence of lymphocytes in the high endothelial venules is consistent with transmural and inter-endothelial passage of these cells.

The microstructural and ultrastructural features of the equine lingual tonsil were studied in five young horses. Located at the root of the tongue it presented an irregular surface with rounded elevations, numerous folds and crypts. Stratified squamous non-keratinized epithelium lining its outer surface was modified by heavy infiltration of lymphoid cells to form reticular epithelium within the crypt. The latter implies a role in initiating and maintaining immune responses to incoming infectious agents and antigens. Lamellated structures resembling Hassall's corpuscle were observed towards the outer surface epithelium. Microplicae were visible by scanning electron microscopy on the surface of both the outer and reticular epithelia. No microvillus cells resembling M cells were observed. The stratum superficiale of the reticular epithelium showed strong affinity for Soybean (SBA), Phosphocarpus tetragonolobus 1 (WBA 1), Ulex europaeus (UEA) and Griffonia simplicifolia 1 isolectin-B4 (GS1-B4). The characteristic lectin binding patterns may be useful for embryological and microbiological investigations. Vimentin filaments were not detected consistent with absence of M cells. Mucus glandular acini in the deeper lamina propria mucosae contained glycogen, acidic, neutral and weakly sulphated mucopolysaccharides. Transmission electron microscopy revealed that the layers of the outer surface and reticular epithelia shared characteristic features except the stratum superficiale, which had nuclei of varying shapes and an abundance of cell organelles. A few mast cells with electron lucent granules and myelinated nerve fibres were localized in the deeper portion.

The human palatine tonsils have surface and crypt stratified epithelium and may be initiated via the epithelium to mount immune responses to various presenting antigens. Here we investigated the expression and function of tight junctions in the epithelium of human palatine tonsils from patients with tonsillar hypertrophy or recurrent tonsillitis. Occludin, ZO-1, JAM-1, and claudin-1, -3, -4, -7, -8, and -14 mRNAs were detected in tonsillar hypertrophy. Occludin and claudin-14 were expressed in the uppermost layer of the tonsil surface epithelium, whereas ZO-1, JAM-1, and claudin-1, -4, and -7 were found throughout the epithelium. In the crypt epithelium, claudin-4 was preferentially expressed in the upper layers. In freeze-fracture replicas, short fragments of continuous tight junction strands were observed but never formed networks. In the crypt epithelium of recurrent tonsillitis, the tracer was leaked from the surface regions where occludin and claudin-4 disappeared. Occludin, ZO-1, JAM-1, and claudin-1, -3, -4, and -14, but not claudin-7, mRNAs were decreased in recurrent tonsillitis compared with those of tonsillar hypertrophy. These studies suggest unique expression of tight junctions in human palatine tonsillar epithelium, and the crypt epithelium may possess an epithelial barrier different from that of the surface epithelium.

Recurrent or chronic adenotonsillar infections mainly affect children and frequently involve otherwise healthy subjects. Therefore, having excluded systemic immunological deficiencies, this disease may be due to a local dysfunction of the epithelial structures at either the rhino or oropharyngeal level. The aim of the present investigation was to analyze structural and immunological aspects of tonsils and adenoids in subjects who underwent adenotonsillectomy because of recurrent inflammatory episodes with fever. Histological studies and analyses of the cytokine patterns were carried out in palatine tonsils and adenoid samples from 105 patients who underwent adenoidectomy and bilateral extracapsular tonsillectomy for chronic inflammatory hypertrophy of these organs; 46 of the 105 cases examined presented hyperkeratosis of the crypt epithelium; in the remaining 59, the epithelium was hyperplastic with no signs of keratosis. Scanning electron microscopy revealed a continuous epithelial surface of polygon-shaped flattened cells with fissures towards the cryptic depressions. Titration of interleukin-1beta and tumor necrosis factor alpha in serum and tissues demonstrated higher concentrations in the adenotonsillar specimens, whereas the rise in interleukin-6 was more modest.

The epithelium of the anal tonsil of the laboratory shrew was studied by scanning and transmission electron microscopy, with particular attention focused on the structure of the epithelium lining the anal tonsillar crypt. The tonsillar crypt surface is lined by two kinds of epithelia: squamous epithelium, which is located mainly at the neck of the crypt and includes keratohyalin granules in the superficial layer, and reticular epithelium, which is invaded by many immigrating cells and has several micropores immigrating cells to pass through. In addition, basal granulated cells are present in the basal layer. These results suggest that the reticular epithelium of the anal tonsil belongs to the well-developed gut-associated lymphoid tissue (GALT) in the alimentary canal. It represents a specialized and important compartment in immunological function, similarly to the palatine tonsils of other mammals, and has as yet unknown roles in digestion.

The antigen presenting cells (APCs) with special interest to dendritic cells (DC), were investigated in 28 hypertrophic and 10 control pharyngeal tonsils of children by histochemistry, immunohistochemistry and electron microscopy. In this study, we are trying to clarify the function and classification of APC in pharyngeal tonsils using morphologic criteria, Human Leukocyte Antigen Monoclonal Antibody (HLA-DR MoAb), which is specific for APCs, and acid phosphatase (APh) reacting with both phagosomes and lysosomes. The surface epithelium of the patient group examined by light microscopy, heavy infiltration of lymphocytes, degenerated columnar cells and a few HLA-DR MoAb (+) columnar cells was observed. Additionally, a significant number of APCs which were Langerhans cells (LCs), interdigitating dendritic cell (IDC), follicular dendritic cell (FDC) and macrophages were stained with both HLA-DR MoAb and APh in the epithelial, interfollicular-subepithelial and follicular areas. Ultrastructural examinations revealed that lymphocytes, macrophages, LC and M cells were found among the surface columnar epithelial cells of the patient group. The interactions between M cells and LC suggested that M cells probably passed antigens from surface to LC. In the interfollicular-subepithelial areas of the hypertrophic pharyngeal tonsil, IDCs were in close contact with lymphocytes, macrophages and plasma cells. Seven types of FDCs (FDC-1 - FDC-7) were recognised according to their ultrastructural appearances. Differentiated FDCs (FDC-4) were also in close contact with each active subtype of FDCs in follicular areas besides lymphocytes. These findings supported the idea that although the pharyngeal tonsils contained several types of active APCs, only DC were in close contact with immunocompetent cells and the other APC's. Therefore, these morphologic appearances of DC could be a sign of function to initiate the immune response of the pharyngeal tonsil.

Little is known about the role of the M cells of human nasopharyngeal lymphoid tissue in the sampling of viruses that cause respiratory infections. To clarify whether M cells could function as a gateway for influenza virus into human nasopharyngeal lymphoid tissue, excised adenoid tissue was incubated in media containing influenza A virus for 30, 60, and 90 min, respectively. Transmission electron microscopic observation revealed that many influenza viruses adhered to M cell surfaces and were taken up into the cytoplasmic vesicles of M cells after 30 min incubation; the viruses had been transported into enfolded lymphoid cells after 60 min incubation. By staining M cells with Sambucus nigra lectin, which specifically recognizes the NeuAcalpha2,6 Gal linkage of sialoprotein, it was also found that abundant receptors for the human influenza virus are present on the M cell surface. Our findings indicated that M cells of human nasopharyngeal tonsils function as a major port for influenza A virus entry and that the virus could be efficiently transferred to enfolded macrophages and lymphoid cells by M cells. The transport of influenza viruses to lymphoid cells by M cells may promote antigen delivery to the immune system, and these findings may be important for systemic delivery of those influenza viruses that have the capacity to productively infect cells outside of the respiratory tract.

The musk shrew, Suncus murinus, is one of the primitive mammals and has a pair of palatine tonsils. In the present study, we investigated the blood microvascular architecture of the tonsil in this animal by scanning electron microscopy of corrosion casts. The paranodular arterioles entered the lymph nodule to form a coarse capillary plexus within the nodule. Some of the arterioles reached the dome region to give rise to a fine meshwork of dome subepithelial capillaries. This dome subepithelial capillary network did not show any hairpin or switch-back patterns, as seen in human and rabbit tonsils. Both of the nodular and dome capillaries were drained into the postcapillary venules in the periphery of the nodular or the paranodular region. On the surface of these cast venules, oval-shaped indentations were seen corresponding to the luminal surface of the high endothelial venules. These venules were collected into the large vein at the bottom of the tonsil. The blood vascular architecture of the musk shrew tonsil is basically the same as those of other mucosa-associated lymphoid tissues in mammals.

To clarify the cellular origin and the fate of M cells, detailed distributions of the epithelial cells were investigated scanning electron microscopically on the follicle-associated epithelia (FAE) of chicken cecal tonsils. The distribution of M cells was closely related with the situation of the crypt orifices in chicken cecal tonsils. In undeveloped cecal tonsils, the intestinal crypts were localized at the periphery of the FAE. In these tonsils, M cells without microvilli (M(0)) were predominantly populated in the basal region of the FAE, whereas goblet cells and microvillous epithelial cells (MV) were more distributed in the middle to the apical region of the FAE. A few M cells with short microvilli were dispersed throughout the FAE. Significantly shrunk MV (MVs) clustered together in transitional portions from the lateral face to the roof of the FAE. In well-developed cecal tonsils, the crypts also opened at the lateral surface in addition to the periphery of the FAE. In these tonsils, the M(0) accumulated densely in the small areas around the crypt orifices exclusively. No sign of exfoliation of apoptotic epithelial cells was found in the M(0)-accumulated areas and at their peripheral boundaries. The MVs were often clustered in the central regions among the crypt orifices in addition to the roof of the FAE. These findings suggest that M cells are directly derived from the undifferentiated crypt epithelial cells, not fall into apoptotic cell death and further differentiate into MV in the FAE of chicken cecal tonsils.

Fluorescence in situ hybridization (FISH) is difficult to accomplish using thin-sections of paraffin-embedded lymphoid tissue because of the high cellularity and truncated cells that interfere with accurate scoring of individual nuclei. We modified and tested a new technique to isolate individual nuclei from tissue cores of paraffin-embedded tissue processed with xylene, proteinase K, citric acid, and pepsin. The efficacy of this method to study paraffin-embedded tissue was investigated in six normal lymph nodes or tonsils and 32 malignant lymphomas including five mantle cell, five follicular, five Burkitt, five extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue, five anaplastic large-cell, and seven diffuse large B-cell. Fusion of CCND1 and IgH, BCL2 and IgH, c-myc and IgH, and MALT1 and API2 were detected using probes with a dual-fusion FISH strategy. Anomalies involving ALK and BCL6 were detected using break-apart FISH probes. FISH studies were successful for each of the 38 specimens. Chromosome anomalies were detected in each malignant specimen, but not in the normal lymphoid tissue. The correct chromosome anomaly was detected in 22 of 22 specimens with genetic abnormalities that were established by other genetic techniques. This FISH technique is useful to detect chromosome anomalies with high sensitivity and specificity in paraffin-embedded tissue and may provide important diagnostic and prognostic genetic information.

The laboratory shrew, Suncus murinus, which lacks such gut associated lymph organs as the appendix and Peyer's plates, was recently demonstrated (Kubo and Isomura, 1996) to possess a pair of anal tonsils at the end of its rectum. The present paper deals with the development of this lymphoid organ as observed by light and electron microscopy. The anal tonsil was characterized by the initial postnatal development. On neonatal Day 1, a pair of epithelial crypts formed at the dorsal boundary between the anus and the ostium urogenitoanale. On Day 2 after birth, lymphocytes began to accumulate in the subepithelial mesenchymal tissue under the crypt. From Day 3 on, the lymphocytes increased to form a lymph nodule, from which, on Day 5, some lymphocytes began to penetrate into the crypt epithelium. The crypt and the nodule were fused together between Days 6 and 8. A germinal center-like structure was observed on Day 20 after birth. Around Day 40, the invading cells comprised cellular units consisting of large and small lymphocytes and plasma cells. High endothelial venules were observed in the parafollicular area at this time. These findings indicate that the anal tonsil originates from an accumulation of lymphocytes in the mesenchymal tissue close to a particular epithelium of the crypt, presumably in response to antigens in foods; the tonsilar structure is then gradually completed by fusion of the lymphoid and epithelial elements. This paper further reports on an electron microscope finding on Day 8 where the anal tonsillar crypt epithelium was seen to contain some basal-granulated cells of the open type.

V(D)J recombination in lymphocytes is mediated by 2 recombination-activating genes, RAG1 and RAG2, which are expressed during lymphocyte development in bone marrow and thymus. Prompted by studies reporting re-expression of the RAGs in germinal center B cells, the expression of RAGs and terminal deoxynucleotidyl transferase (TdT) in human lymphoid tissues was examined using in situ hybridization and immunohistochemistry, respectively. Here it is shown that RAGs and TdT are not reinduced in germinal center reactions. However, RAG(+)/TdT(+) cells are frequently present in extrafollicular areas of tonsils mainly at the boundary between lymphoid tissue and fibrous scaffold. Phenotypic analyses suggest that these cells are B cells. Finally, it is shown that RAG(+)/TdT(+) cells are found more frequently in tonsils than in other peripheral lymphoid tissues. This may reflect an increased influx of RAG(+)/TdT(+) cells as a result of higher antigenic stimulation at this site. Alternatively, this observation may indicate that the tonsils are an additional site of lymphocyte ontogeny.

Eleven palatine tonsils were collected from subjects who underwent tonsillectomy in Christian Medical College Hospital and the route of migration of lymphocytes through the high endothelial vessel was studied under EM. In the interendothelial route, migration of a lymphocyte through HEV wall began with the adhesion of a lymphocyte to the surface of endothelial cells by means of a short cytoplasmic projection in the vicinity of intercellular space. The projection extended into the cleft between adjacent endothelial cells. The lymphocyte migrated through HEV by diapedesis. After the lymphocyte had traversed the interendothelial space, it occupied the subendothelial space. In the transendothelial route, migration of a lymphocyte through HEV was initiated by adherence of the lymphocyte to the endothelial cell. The adherent lymphocyte compressed or invaginated into the cytoplasm of the endothelial cell, entered the endothelial cell, was completely enclosed within the endothelial cell cytoplasm, and emerged from the endothelial cell to occupy the subendothelial space. Evidence is presented from static transmission electron microscopic pictures for the migration of lymphocytes by both interendothelial and transendothelial routes through the high endothelial venule.

The follicular dendritic cell (FDC)-lymphocyte cluster is rich in the follicular light zone of the secondary lymphoid follicles (LFs). Although, the mantle zone (MZ) also has FDC-lymphocyte cluster, it has not known about what kind of adhesion molecules relates to cluster formation. In the present study, we investigated whether the adhesion molecules, L-selectin (CD62L) and sialyl Lewis x (CD15s) can mediate the formation of the cluster in human tonsillar LFs. The MZ only expressed both the adhesion molecules in the secondary LF. Isolated FDC-lymphocyte clusters were composed of CD62L(+) lymphocytes and CD15s(+) FDCs. Stamper-Woodruff binding assay revealed that the binding of IgD(+) lymphocytes was significantly inhibited by pretreatment with anti-CD62L antibody or with anti-CD15s antibody. These results indicate that CD62L on MZ lymphocytes and CD15s on FDCs may play a role of the cluster formation, unlike the clusters in the other parts of LFs.

Samples of normal bovine palatine tonsils were examined by light and electron microscopy. Like human tonsils, they were composed of crypts, subepithelial areas, follicles, and T-dependent zones, but their well-developed capsule subdivided the lymphoid tissue by connective septa. B cells formed the major lymphoid component. The follicles and T-dependent zones had morphological and histochemical features typical of peripheral lymph organs. Follicular dendritic cells were isolated and shown to be similar to human follicular dendritic cells.

Telomere length maintenance, usually executed by telomerase, is a prerequisite for an extended or infinite division potential. Nevertheless most telomerase positive normal cells exhibit telomere shortening. This study details the telomerase expression and telomere dynamics in purified tonsil B cell subsets during the germinal center (GC) reaction. Significant telomere lengthening was observed as naive B cells matured to centroblasts and when centroblasts matured further to centrocytes, resulting in an increase in telomere length of about 4 kbp determined by Southern blotting. Immunopurified cell populations were also studied by fluorescence in situ hybridization and flow cytometry (flow-FISH) confirming that the GC B cells exhibited lengthened telomeres. These data were further verified in unpurified tonsil cells by combining flow-FISH and immunophenotyping using selected surface markers. Centroblasts expressed high levels of telomerase activity, which was increased in centrocytes, whereas resting naive, activated naive and memory B cells were telomerase activity negative. Expression levels of the catalytic subunit (hTERT) RNA paralleled the telomerase activity levels. The unique telomere elongation in GC B cells permits extensive proliferation during the GC reaction and provides the memory cells with a substantial increase in division potential. Understanding the telomere biology of GC cells is important in defining requirements for telomere elongation in vivo, with implications for the normal immune system as well as for lymphomas, and could provide insights into how the division potential of cells can be manipulated in vitro.

The aim of this study was to characterise the morphological and histochemical features of equine nasopharyngeal tonsillar tissue. Nasal and oropharyngeal tonsillar tissue has been described as the gatekeeper to mucosal immunity because of its strategic location at the entrance to the respiratory and alimentary tracts. A combination of light, scanning and transmission electron microscopy has revealed the presence of follicle-associated epithelium (FAE) overlying lymphoid tissue of the equine nasopharyngeal tonsil caudal to the pharyngeal opening of the guttural pouch. Membranous microvillus (M) cells were identified in the FAE on the basis of short microvilli, an intimate association with lymphocytes, cytoplasmic vimentin filaments and epitopes on the apical surface reactive with lectin GS I-B4 specific for alpha-linked galactose. CD4-positive lymphocytes were scattered throughout the lamina propria mucosae as well as forming dense aggregates in the subepithelial part. The central follicular area was heavily populated with B lymphocytes and the dome and parafollicular areas contained both CD4- and CD8-positive lymphocytes. CD8-positive lymphocytes were also present in the epithelium and, together with B lymphocytes, in small numbers in the lamina propria mucosae. These observations indicate that the nasopharyngeal tonsil is potentially an important mucosal immune induction site in the horse and an appropriate target for intranasally administered vaccines.

Bacterial penetration into epithelial cells, scraped from the palatine tonsils of 14 patients (10 males, four females; median age 16 years) with current infectious mononucleosis and concomitant membranous tonsillitis, was studied using the transmission electron microscopic (TEM) technique. Bacteria were seen to adhere to and penetrate the epithelial cells, some of which were completely filled with bacteria. This finding suggests intracellular proliferation of bacteria. Epstein-Barr virus, the causative agent of infectious mononucleosis, especially when associated with growth of beta-haemolytic streptococci on the palatine tonsils, induces bacterial penetration into tonsillar tissue, that in turn might be a causative mechanism in the development of peritonsillar abscess.

To clarify the nature of M cells, the detailed ultrastructural characteristics and lectin-binding properties of M cells were investigated in follicle-associated epithelium (FAE) of chicken caecal tonsils. M cells presented various outlines from columnar to dome shaped. Their polymorphism was dependent on the number of harboured intraepithelial migrating cells. The lighter and larger nuclei of M cells were situated at more apical levels in the epithelial lining compared with those of neighbouring microvillous epithelial cells. The microvilli, which were significantly shorter and thicker than those of adjacent microvillous epithelial cells, were sparsely distributed or completely absent on the apical surfaces of M cells. In general, the apical cytoplasm of M cells without microvilli protruded slightly into the intestinal lumen. Numerous small vesicles were often contained in the apical cytoplasm. The numerous small invaginations of the apical and lateral cell surfaces suggested active transportation of luminal substances. No canaliculi existed in the apical cytoplasm of M cells whereas they were often detected in the neighbouring microvillous epithelial cells. A noteworthy finding was the frequent detection of multivesicular bodies in the apical cytoplasm of M cells. These multivesicular bodies suggest some degradation of ingested luminal substances during transcytoplasmic transportation. WGA and 4 other lectins strongly reacted with all epithelial cells except for M cells, this negativity suggesting a means of detecting M cells in chicken caecal tonsils. Three lectins, DSL, ConA and Jacalin, reacted weakly with the glycocalyx on M cells. The positive reactivity might allow chicken M cells to be utilised for specific antigen delivery into the mucosal immune system in some parenteral vaccinations.

Background: Primary ciliary dyskinesia (PCD) is an inherited disease characterized by specific ultrastructural defects of cilia and sperms. The impairment of mucociliary clearance (MCC) results in chronic respiratory infections and subsequently in bronchiectasis., Main Purpose: The evaluate rational decisions in early diagnosis of PCD., Methods: Samples of nasal mucosa or tissue of tonsilla pharyngea after adenotomy were studied by transmission electron microscopy (TEM) in 47 patients aged 1-15 years, suffering from recurrent or chronic respiratory infections., Results: Congenital ultrastructural ciliary defects specific for PCD--the lack of dynein arms, radial spokes defects and microtubular transposition--were observed in 13 patients. TEM investigation is an expansive, time consuming method not available in routine practice. Therefore we have evaluated a diagnostic procedure which uses available examination methods focused on the diagnoses of PCD. TEM of respiratory cilia is indicated in patients with situs viscerum solitus if chronic respiratory disease develops and after more frequent causes--asthma, cystic fibrosis, congenital anomalies of respiratory system and immunodeficiency had been excluded., Conclusions: The correct and early diagnosis is important for effective therapy in order to improve MCC. This approach can prevent the development of bronchiectasis during childhood.

The changes appearing during the development of the human palatine tonsil, both in the surface and in the tonsillar crypt epithelium, were studied from samples of the 16th to 40th prenatal weeks. From the 18th week, we observed areas of mesh-like epithelium in an originally homogeneous stratified squamous epithelium, i.e. the reticularisation began in the tonsillar crypt epithelium. The important role of the epithelial basal membrane in this process is discussed. The diffuse spongy-form type of reticularisation as well as the formation of the intraepithelial passages between the epithelial columns are described. The lymphoid cells and macrophages migrated through these microcrypts and they were frequently seen near the crypt epithelial micropores on the surface of the reticularised epithelium.

Bacterial swabs were collected from the tonsillar surfaces of eight patients with current acute tonsillitis, culture-positive for Streptococcus pyogenes. Using gold-labelled antiserum to S. pyogenes, these micro-organisms could be localized in the samples by transmission electron microscopy. S. pyogenes pathogens were further characterized with gold-labelled antiserum to human IgG and SIgA antibodies. Roughly 90% of the pathogens were found coated with IgG antibodies, irrespective of the duration of the disease, whereas the proportion of SIgA-coated pathogens increased with disease duration. Insufficient IgA coating of pathogens might well be a contributory cause of the induction of tonsillar infection, probably due to inadequate prevention of the attachment of the S. pyogenes bacteria to the tonsillar surface epithelium.

By removing all or most organelles, we have exposed the cytoplasmic side of the plasmalemma and its specializations in serous cells and in cells of striated and excretory ducts of human major salivary glands. The areas of plasmalemma located beneath the lumen and those bordering the intercellular canaliculi are covered by evenly distributed particles arranged in a continuous band and, below it, in regularly spaced clusters. A similar pattern of particles is seen on the internal aspects of the juxtaluminal plasmalemma of cells of both striated and excretory ducts. Small isolated clusters of particles are seen in other regions of serous and ductal cells as well, being particularly numerous along the basal processes of cells of striated ducts. A distribution of particles resembling that present along intercellular canaliculi of serous cells also is seen on the plasmalemma bordering the biliary canaliculi where, however, the clusters look smaller and farther apart. Large clusters of particles, matching those seen on salivary glands and on liver, are present at the base of the short processes of cells of the stratum spinosum of squamous stratified epithelia. Since the sites of location of the clusters closely correspond to the areas where transmission electron microscopy (TEM) reveals the presence of desmosomes, we believe that the clusters may be related to these cellular junctions. Of more difficult interpretation are the particles present on the juxtaluminal band corresponding both to the zonula occludens and to the zonula adhaerens.

Tonsils of the soft palate of pigs are the main oropharyngeal lymphoid tissues that protect the body against antigens entering through the mouth. The aim of this work was to elucidate the intercellular and lymphatic pathways by which lymph and cells are transported through these tonsils. Tonsillar tissue from freshly-killed pigs was examined using light microscopy and electron microscopy, or was injected with Mercox for scanning electron microscopy of corrosion casts. Intercellular fluid passes between epithelial cells and is continuous with that of the subepithelium. Fluid from the subepithelium flows into sinuses that form a network around the apex of follicles. These sinuses are continuous with parafollicular sinuses that penetrate the parafollicular tissue between the follicles. Some parafollicular sinuses are traversed by a complex network of cell processes, whereas others appear to lack such processes. Some parafollicular sinuses are closely located (10 microm) to venules; others lie adjacent to the follicle capsule. No lymphatics enter or leave the follicles. All lymph from the tonsils must traverse parafollicular sinuses before entering septal vessels, and these are continuous with basal vessels. Basal vessels coalesce to form efferent vessels that transport lymph from the tonsil to the primary lymph nodes. Septal, basal and efferent lymphatic vessels contain prominent valves and many lymphocytes. Lymphatic sinuses appear to be a significant pathway for lymphocytes migrating from the tonsillar lymphoid tissue.

In tonsils of the soft palate of pigs high endothelial venules (HEV) occur throughout the parafollicular region. In some regions of the venules the endothelial lining is uniformly high; in other areas, mainly the nuclear region of the endothelial cell protrudes into the lumen and the cytoplasmic region is attenuated. In this portion of the venule endothelial cells may traverse the lumen of the vessel to form intravascular bridging processes. The endothelial cells are characterised by pinocytotic vesicles, many surface microvilli, cytoplasmic processes and local cell-cell contacts with adjacent endothelial cells. These specialised HEV may play a role in the unusual pattern of lymphocytes from tonsillar tissue into blood. In the tonsils of the soft palate of pigs, HEV may mediate both lymphocyte migration to and from the lymphoid tissue. Further investigation is required to determine the importance of these 2 migration pathways.