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In contrast to mammals, early B cell differentiation and diversification of the antibody repertoire in chickens do not take place in the bone marrow but in a specialized gut associated lymphoid tissue (GALT), the bursa of Fabricius. During embryonic development, B cell precursors migrate to the bursa anlage, where they proliferate and diversify their B cell receptor repertoire. Around hatch these diversified B cells start to emigrate from the bursa of Fabricius and populate peripheral lymphoid organs, but very little is known how the migratory processes are regulated. As CXCL12 (syn. SDF-1) and CXCR4 were shown to be essential for the control of B cell migration during the development of lymphoid tissues in mammals, we analyzed expression and function of this chemokine/chemokine-receptor pair in the chicken bursa. We found a strong variation of mRNA abundance of CXCL12 and CXCR4 in different stages of bursa development, with high abundance of CXCL12 mRNA in the bursa anlage at embryonic day 10 (ED10). In situ hybridization demonstrated disseminated CXCL12 expression in the early bursa anlage, which condensed in the developing follicles and was mainly restricted to the follicle cortex post-hatch. Flow cytometric analysis detected CXCR4 protein already on early B cell stages, increasing during bursal development. Post-hatch, a subpopulation with the hallmarks of emigrating B cells became detectable, which had lower CXCR4 expression, suggesting that downregulation of CXCR4 is necessary to leave the CXCL12-high bursal environment. In vivo blockade of CXCR4 using AMD3100 at the time of B cell precursor immigration strongly inhibited follicle development, demonstrating that CXCL12 attracts pre-bursal B cells into the bursal anlage. Altogether, we show that CXCL12 and its receptor CXCR4 are important for both populating the bursa with B cells and emigration of mature B cells into the periphery post hatch, and that CXCR4 function in primary B cell organs is conserved between mammals and birds.

Summary Two and 14-day old chickens were busectomized (B), thymectomized (T), testosterone-treated (t) (five doses of 1 μg. per kg. body weight, a dose every two days), or subjected to combinations of these interventions. Animals were sacrificed at 10 days after operation or beginning of treatment, and pectoral muscle was analyzed. Protein content was generally lowered (even that of the myofibrillar fraction in younger t chickens). RNA and DNA contents were generally lowered, but important differences occurred between age-groups. Bt and Tt combinations did not lead to summation of the effects of the two procedures. Zusammenfassung Endokrine Einflusse auf den M. pectoralis von Kuken: Beziehungen zwischen Thymus, Bursa Fabricii und Testosteron Bei Kuken im Alter von 2 und 14 Tagen wurden folgende Eingriffe vorgenommen: Bursektomie (B), Thymektomie (T), Testosteron-Applikation: 5mal in Abstanden von 2 Tagen je 1 μg/kg KGW (t) oder Kombinationen dieser Behandlungen. 10 Tage nach der Operation oder nach dem Behand-lungsbeginn wurden die Tiere getotet und der Brustmuskel analysiert. Der Protein-Gehalt war allgemein erniedrigt, selbst in der myofibrillaren Fraktion der jungeren t-Kuken. RNS und DNS-Gehalte waren ebenfalls erniedrigt, wobei zwischen den Altersgruppen deutliche Unterschiede bestanden. Nach Bt- und Tt-Kombinationen konnte kein additiver Effekt der beiden Behandlungen beobachtet werden. Resume Influences endocrines sur M. pectoralis du poussin: Rapport entre Thymus, Bursa Fabricii et Testosterone Les interventions suivantes ont ete faites chez des poussins âges de 2–14 jours: boursectomie (B), thymectomie (T), application de testosterone (t) (5 fois en l'espace de 2 jours et chaque fois 1 μg/kg de poids). On a egalement procede a une combinaison de ces traitements. Les animaux ont ete sacrifies 10 jours apres l'operation ou le debut du traitement et on a analyse M. pectoralis. Le taux de proteines fut en general diminue, meme dans la fraction myofibrillaire des plus jeunes poussins (t). Les taux d'ARN et d'ADN furent egalement abaisses, de nettes differences existant entre les differentes classes d'âge. Aucun effet additif n'a ete observe apres des combinaisons Bt et Tt. Resumen Influjos endocrinos sobre el musculo pectoral del pollito: Correlaciones entre el timo, la bolsa de Fabricio y la testosterona En pollitos de 2 y 14 dias de edad se efectuaron las intervenciones siguientes: bursectomia (B), timectomia (T), aplicacion de testosterona (t): 5 dosis de 1 mg/kg PC, facilitandose una dosis cada dos dias, o combinaciones de estos tratamientos. Se sacrificaron los animales a los 10 dias despues de efectuada la operacion o tras el comienzo del tratamiento, analizandose el musculo pectoral. Por lo general, se hallaba disminuido el contenido en proteina, incluso en la fraccion miofibrilar de los pollitos t mas jovenes. Tambien estaban reducidos los niveles de RNA y DNA, existiendo diferencias importantes entre los grupos por edades. Las combinaciones Bt y Tt no indujeron ningun efecto aditivo a los dos procedimientos.

Summary Studler-Cornish chicken of 5 days were treated with Cyclophosphamide (Cy) in a dose of 3 mg./100 g. body weight. Such a treatment affected preferentially and persistently the metabolism of nucleic acids in the bursa Fabricii. In the thymus Cy induced a decrease of RNA and total protein content only in the first phase of the experiment. Later on their content increased for a short period of time, returning then to the normal value. After Cy treatment a hypersecretion of steroids by the adreanal was also noted between 12 and 23 days of the experiments. The excess of steroids seems to potentiate the Cy effect. This is connected with the inhibitory effect of cortisol on humoral immunity. Zusammenfassung Einflus einer immunsuppressiven Behandlung mit Cyclophosphamid auf die Reaktionen von Thymus und Bursa 5 Tage alte Kuken wurden mit 3 mg (100 g Kpgew. Cyclophosphamid (Cy) behandelt. Durch die Behandlung wurde vorwiegend der Nukleinsaure-Stoffwechsel in der Bursa Fabricci beeinflust. Im Thymus kam es nur anfangs zu einem Absinken des RNS und Gesamtproteingehaltes. Spater stieg der Spiegel kurze Zeit wieder an und kehrte dann zum Normalwert zuruck. Nach Cy-Behandlung kam es auch zu einer vermehrten Ausscheidung von Steroiden in den Nebennieren am 12.–23. Tag des Experiments. Dadurch wird der Cy-Effekt potenziert, wobei der hemmende Einflus von Cortison auf die humorale Immunitat von Bedeutung ist. Resume Influence d'un traitement immunosuppressif avec un cyclophosphamide sur les reactions du thymus et de la bourse de Fabricius Des poussins de 5 jours ont ete traites avec 3 mg de cyclophosphamide (Cy). Le traitement a particulierement influence le metabolisme des acides nucleiques dans la bourse de Fabricius. Il n'y a eu au debut qu'un abaissement d'ARN et du taux total des proteines dans le thymus. Le taux remonta ensuite rapidement pour atteindre une valeur normale. Le traitement a la cyclophosphamide provoqua une augmentation de la secretion des steroides dans les glandes surrenales du douzieme au vingt-troisieme jour de l'experience. Cela eut pour effet de potentialiser l'action de Cy etant donne l'influence inhibitrice significative de la cortisone sur l'immunite humorale. Resumen Influjo del tratamiento inmunosupresivo con ciclofosfamida sobre las reacciones de timo y bolsa de Fabricio Pollitos de 5 dias de edad (100 g.) recibieron 3 mg. de ciclofosfamida (Ci). Mediante el tratamiento se influyo de forma predominante en el metabolismo de los acidos nucleicos en la bolsa de Fabricio. En el timo se produjo solo al principio un descenso del ARN y contenido en proteinas totales. Despues volvio a aumentar el nivel por poco tiempo, volviendo luego al valor normal. Tras el tratamiento con Ci se produjo tambien una eliminacion acrecentada de esteroides en los adrenes durante los dias 12°–23° del experimento. De ese modo se potencia el efecto de la Ci, siendo importante el influjo inhibidor de la cortisona sobre la inmunidad humoral.

The present study was carried out to analyse the vascularization of the pigeon bursa cloacalis of Fabricius and to determine whether it undergoes age-dependent changes during its functionally most important growth period after hatching of the pigeon. Morphological assessment of vascular corrosion casts, studied qualitatively and quantitatively, was applied for the first time to investigate the vascularization of the pigeon pigeon bursa of Fabricius. This also allowed us to analyse the microvasculature and morphological aspects of the vessel interrelationships as occurring in the natural state. The casts were compared with histological sections stained by haematoxylin-eosin and by binding of the lectin e-PHA (Phaseolus vulgaris, erythroagglutinin) to blood vessels. The vascular architecture of the bursa of Fabricius of the pigeon revealed that the organ is irrigated via two pathways, first through the terminal capillary system of lymphoid follicles arising from the internal pudendal artery, and secondly through arteries originating from the cloacal vasculature of the collum of the organ supplying the periluminal capillary system of the pigeon bursa of Fabricius. Both systems are drained by a venous system which is collateral to the system of the internal pudendal artery and clearly functions as a direct link between the lumen and vasculature of the cloaca or gut, respectively, and the bursa fabricii. This could allow the lymphocytes to be confronted with antigens from the contents of the gut, and their subsequent transport into the secondary lymphoid organs of the organism. Our results demonstrate that the blood vessels, as major and supplying part of the lymphoid system of the bursa Fabricii, clearly reflect three different phases of development: the evolution phase from about day 20 until day 50 post-hatching, the mature phase from days 50 to 90, and the involution phase after day 90. During the evolution phase the density of the vessel system rapidly increases, while in the mature phase the vascular architecture is maintained. The involution phase is dominated by vascular degeneration combined with shrinkage of the whole organ. Therefore, the morphology of the vasculature distinctly reflects the functional status of this primary lymphoid organ during its lifespan.

Cryptosporidiosis is one of the main protozoan infections in birds. It manifests as either a respiratory or a digestive illness, and it affects a very large number of avian species across several continents. The aim of this review is to report on the main results of studies on cryptosporidiosis among birds and the importance of these results to veterinary medicine and public health. A criptosporidiose constitui-se em uma das principais infecções por protozoários em aves, manifestando-se como enfermidade respiratória ou digestiva, em dezenas de espécies aviárias, em vários continentes. O objetivo desse trabalho foi relatar, por meio de revisão de literatura, os principais resultados de estudos sobre criptosporidiose em aves e sua importância para a medicina veterinária e saúde pública.

Summary Studler-Cornish, tetralinear hybrid chickens, aged 14 days, were injected intrapectorally with 1, 3.5 and 5. mg./100 g. body weight DOCA. After 3 days a constant increase of thymus and bursa weight and RNA content was found, while the quantity of glycogen decreased. The quantity of DNA and total proteins showed variable or insignificant changes. In the adrenals the level of ascorbic acid increased. Zusammenfassung Der Einflus von Desoxycorticosteron auf den Thymus und die Bursa Fabricii beim Kucken Tetralinearen Hybridenkuken der Studler-Cornish Rasse wurden im Alter von 14 Tagen in den M. pectoralis DOCA injiziert (Dosen: 1, 3,5 und 5 mg/100 g Korpergewicht). Nach 3 Tagen wurde bei allen Tieren eine Gewichtserhohung des Thymus und der Bursa Fabricii festgestellt, deren Gehalt an RNS war erhoht, derjenige an Glykogen hingegen vermindert. Der Gehalt an DNS and Totalprotein zeigte teils unterschiedliche, teils nicht signifikante Veranderungen. Der Askorbinsauregehalt der Nebennieren war erhoht.

Humoral immune responses in birds, contrary to mammals, depend on the normal functioning of bursa Fabricii. Recent studies have delivered new information about the structure, development and origin of cells that compose the bursa environment. Several viral infections affect bursa, causing lymphocyte depletion or excessive proliferation. This review summarizes data on the development and histology of healthy bursa and introduces some common disorders that affect this organ.

The article "The bursa of Fabricius and antibody production" by Bruce Glick, Timothy S. Chang, and R. George Jaap first demonstrated the role of the bursa in immune development. Birds, including chickens, possess a peculiar organ, the bursa of Fabricius. The organ was recognized for more than 300 yr before its function was described in 1956. Discovery of the bursa as an essential component of the immune response began by accident. Removal of the bursa, bursectomy, during the rapid growth period diminished the antibody response to Salmonella. A paper describing this exceptional finding was initially rejected by Science and ultimately published in Poultry Science. This revelation triggered sequential events leading to the understanding of the dichotomy of the immune response. Additional work in multiple laboratories over many years revealed fundamental immune mechanisms attributable to the bursa. Understanding those mechanisms advanced agricultural and biomedical science.

The development of the bursal follicle and the appearance of the follicle-associated epithelial (FAE) cell and the reticuloepithelial (REp) cell were studied. The stages of development of the bursal follicle were observed by light and electron microscopy; an anticytokeratin monoclonal antibody was also used. At the beginning of follicle development, a mesenchymal cell cluster is observed in the tunica propria; the cluster becomes wedged in a niche of the surface epithelium, and gradually it is completely surrounded by the epithelium itself, which closes under the clump of mesenchymal cells. The epithelial cells lying upon the mesenchymal clump become necrotic, and a number of mesenchymal cells bulge out, forming the FAE cells. The epithelial cells that have closed under the mesenchymal nodule become stratified and form the REp cells; they become star-shaped because the medullary-lymphoid cells grow between them. Finally, the cortex is formed, possibly as a result of the migration of medullary cells before they peripheralize. It is concluded that FAE cells are not specialized epithelial cells, as they do not react to an anticytokeratin monoclonal antibody; on the contrary, they are formed by mesenchymal stemcells that bulge into the lumen and change their character after moving into the epithelium. The REp cells appear in the follicular primordium shortly after the bursal follicle begins to develop; the pronounced reactivity of the REp cells to an anticytokeratin monoclonal antibody supports the hypothesis of their epithelial origin.

Summary To study the clinical and pathological manifestations of Cryptosporidium infections, 24 h-old chickens were inoculated via four routes: orally, nasally, cloacally and by contamination, using 10 5 oocysts of Cryptosporidium in each case. The chickens began to shed oocysts of Cryptosporidium on days 7 to 8 after inoculation. There was no difference in the clinical manifestations or histological damage with respect to the inoculation routes. Various developmental stages of Cryptosporidium were also demonstrated microscopically in the smears or sections of bursa of Fabricii, larynx, trachea and cecal tonsils of inoculated chickens. Although the intestinal mucosa and respiratory tract mucosa were scarcely infected with the parasites, the bursa Fabricii was heavily infected in association with hypertrophy and hyperplasia of the lining epithelial cells.

Summary Antibody response of dysgammaglobulinemic chickens and of immunologically intact controls (LSL) after immunization with haptens (DNP, MATP) coupled to carrier proteins was investigated. Only one group of dysgammaglobulinemic chickens showed an IgG-antibody response comparable to that of control chickens. Carrier preimmunization caused a strong antibody response of all the chickens. The mitogenic LPS effect resulted in increased serum IgG-level of the dysgammaglobulinemic chickens. BG-cell specific tolerance as a consequence of a retarded bursal development is discussed as a possible reason of the dysgammaglobulinemia. Zusammenfassung Die Antikorperantwort dysgammaglobulinamischer und immunologisch intakter Kontrollhuhner auf eine Immunisierung mit an Trager gekoppelten Haptenen (DNP; MATP) wurde untersucht. Nur eine Gruppe der dysgammaglobulinamischen Huhner zeigte eine den Kontrollwerten vergleichbare IgG-Antikorper-Antwort. Die Vorimmunisierung mit dem Trager (HSA) verursachte bei allen Tieren hohe Antikorpertiter. Der mitogene Effekt von LPS fuhrte zu einer Erhohung der Serum-IgG-Konzentration der dysgammaglobulinamischen Huhner. Als mogliche Ursache der Dysgammaglobulinamie wird eine BG-zellspezifische Toleranz als Konsequenz einer verzogerten Entwicklung der Bursa Fabricii diskutiert.

The histological changes occurring in the bursa of Fabricius and in the thymus of 4-week-old pigeons after cyclophosphamide (Cy)-treatment are described. The bursa underwent atrophy and lymphoid cells virtually disappeared from the follicles in which only the reticulo-epithelial cells persisted. The thymus also showed marked degeneration accompanied by lymphocyte depletion. The development of lesions ceased 4 days after the beginning of treatment in the thymus and 6 days later than this in the bursa. After 2 weeks, the two organs showed regeneration. The histological appearance of the thymus returned to normal after 3 weeks and that of the bursa after 7 weeks. Cy-treatment of pigeons produced a profound B and T-cell deficiency which is more transient for T-cells.

A new theory implies that the epithelium of the gut in e.g. fishes is a first level lymphoid organ with the same influence on lymphocytes and lymphoid tissue as the bursa Fabricii in birds. The mammals may be in the process of developing a special bursa equivalent—the epithelium covering the gut-associated lymphoid tissue. But even in mammals the epithelium of the whole gut may function as a bursa Fabricii. In this investigation a series of questions about the kinetics of the lymphocytes within the gut epithelium in germfree and conventional rats has been asked and partly answered. At least 2–3 per cent of the lymphocytes within the gut epithelium, here called theliolymphocytes, synthesize DNA in situ . As many as 12 per cent of the theliolymphocytes at the tip of the villi of the small intestine are less than three days old. These data, and other data on the theliolymphocytes given in this paper, can be best explained by the assumption that theliolymphocytes are to a large extent immigrants, and that these immigrants constitute a selection of young lymphocytes compared to the ordinary mixture of mostly old blood lymphocytes. There is some weak evidence that the theliolymphocytes do not leave the body together with the epithelial cells at the tip of the villi, but reenter the lamina propria. The absence of clearcut differences between germfree and conventional animals regarding the kinetics of the theliolymphocytes supports the original theory. The theory discussed in this article was partly based on the assumption that fishes, amphibians and reptiles did not show demonstrable gut-associated lympho-epithelial organs, to which a bursa function could be ascribed. However, such microscopical lympho-epithelial organs have recently been demonstrated in the gut of fishes and reptiles (Fichtelius, Finstad, Good, to be published). The structure of all these organs is characterized by a close spatial relationship between epithelium and collections of lymphocytes within the lamina propria of the gut. The kinetics of theliolymphocytes and proprialymphocytes is still very interesting, even if the diffuse bursa equivalent of vertebrates very probably includes both the epithelium and part of the proprialymphocytes.

A proposed operational technique is described whereby the intestinal flow from the Bursa of Fabricius in chickens at hatching is excluded.

Summary Ablation of the bursa Fabricii, thymus or both lymphatic organs in chicks of different ages induces modifications in the protein (total protein, RNA and DNA contents), carbohydrate (glycogen content and phosphorylase activity) and oxidative (cytochrome oxidase activity) metabolism of the pectoral muscle. The modifications seem to be mediated by the adrenals. Zusammenfassung Wirkung der Extirpation der Bursa Fabricii und des Thymus auf den Stoffwechsel des Brustmuskels der Kucken Die Exstirpation der Bursa Fabricii und des Thymus bzw. der beiden lymphatischen Organe bei verschieden alten Kucken verandert den Protein-Kohlenhydrat- und Oxydationsstoffwechsel des M. pectoralis (Totalprotein, RNS- und DNS-Gehalt, Glykogengehalt, Phosphorylase-Aktivitat, Cytochromoxidase-Aktivitat. Die Wirkungen scheinen durch den Einflus der Nebennieren ausgelost zu werden. Resume Action de l'extirpation de la bourse de Fabricius et du thymus sur le metabolisme de la musculature du brechet chez des poussins L'extirpation de la bourse de Fabricius et du thymus ou des deux organes lymphatiques chez des poussins d'âges differents modifie le metabolisme proteine-hydrate de carbone et d'oxydation, le taux du glycogene, l'activite de la phosphorylase et de la cytochromoxydase. Les effets semblent etre declenches par l'influence des glandes surrenales. Resumen Efecto de la ablacion de la bolsa de Fabricio y del timo sobre el metabolismo del musculo pectoral en los pollitos La extirpacion de la bolsa de Fabricio y del timo resp. de ambos organos linfaticos en pollitos de edades diferentes induce modificaciones en el metabolismo de las proteinas, hidratos de carbono y oxidativo del musculo pectoral (proteina total, contenidos en ARN y ADN, contenido en glucogeno, actividad de la fosforilasa y actividad de la citocromooxidasa). Las modificaciones parecen ser desencadenadas por las anterrenales.

Summary Studler-Cornish chickens (5-day-old) were injected intradermally with 0.2 ml. (40,000 cells) per 50 g. body weight of lyophilised BCG. The first effect was a significant thymus involution expressed by a decrease in gland weight and nucleic acid content and an increase in thymic glycogen. At the same time depletion of ascorbic acid in the adrenal indicated hypersecretion of corticosteroid hormones in response to stress. The immunological significance of the reactions of the Bursa Fabricii to BCG awaits explanation. Zusammenfassung Die Reaktion von Thymus, Bursa und Nebenniere auf Bacillus Calmette-Guerin (B. C. G.) Studler-Cornish Kuken erhielten im Alter von 5 Tagen intradermal 0,2 ml (40 000 Zellen) pro 50 g KGW lyophilisiertes BCG. Als erstes zeigte sich eine signifikante Thymusinvolution in Form einer Abnahme des Organgewichtes und des Nukleinsauregehaltes und einer Zunahme des Thymus-Glykogens. In der Nebenniere kam es zu einer Abnahme der Ascorbinsaure als Zeichen einer Hypersekretion von Corticosteroiden in Beantwortung eines Stres. Die immunologische Bedeutung der Bursa-Reaktionen gegenuber BCG mus noch geklart werden. Resume La reaction du thymus, de la bourse de Fabricius et des glandes surrenales au bacille de Calmette-Guerin (B. C. G.) Des poussins Studler-Cornish ont recu par voie intradermale a l'âge de 5 jours 0,2 ml (40 000 cellules) de BCG lyophilise par 50 g de poids. En premier se manifesterent une involution significative du thymus sous forme d'une diminution de poids et du taux d'acides nucleiques et une augmentation du glycogene du thymus. On a observe une diminution de l'acide ascorbique dans les surrenales due a une hypersecretion des corticosteroides en reponse a un stress. La signification immunologique des reactions de la bourse de Fabricius vis-a-vis du BCG doivent etre encore expliquees. Resumen La reaccion del timo, bolsa de Fabricio y anterrenales sobre el bacilo de Calmette-Guerin (B. C. G.) Pollitos Studler-Cornish recibieron a la edad de 5 dias por via intradermica 0.2 ml. (40 000 celulas) por 50 g. de peso vivo de BCG liofilizado. Como primero, se mostro una involucion significante del timo en forma de una disminucion del peso del organo y del contenido en acido nucleico y un aumento del glucogeno del timo. En la anterrenal se registro una disminucion del acido ascorbico como signo de una hipersecrecion de corticoesteroides en respuesta a un stress. Todavia queda por aclarar la importancia inmunologica de las reacciones de la bolsa frente al BCG.

The aim of the present experiment was to verify whether the origin of the DIA is ectodermal or endodermal. A rabbit serum against the epithelial cells of the final portion of the cloaca was prepared. The indirect immunofluorescence method was applied to strips obtained with a cryostat, carefully cut in such a way as to include a part of the cloaca, the burso-cloacal stalk, the DIA, and the bursal plicae. In this way, it was possible to demonstrate that the epithelium of the cloaca, of the burso-cloacal stalk, and of the DIA exhibited an intense fluorescence that could not be observed at the level of the epithelium of the bursal plicae. These findings would appear to indicate that the DIA, like the cloaca and the burso-cloacal stalk, is ectodermal in origin. Furthermore, histological study revealed that the DIA exhibits close structural analogies with the dorsal wall of the cloaca. In both areas, unorganized lymphoid infiltrations of the tunica propria can be seen, and the epithelium does not show any follicle-associated epithelial cells. The glands often assume the aspect of dilated crypts containing intestinal transit material. The epithelium of these glands reveals lymphoid infiltrations at various points, and it is not uncommon to detect accumulations of cells in their lumina. Several groups of eosinophilic granulocytes can also be observed in the tunica propria of these two areas, with a clear predominance at the level of the DIA. These similarities between the cloaca and the DIA might lead one to suppose the existence of a functional as well as a morphological correspondence.

An intravenous injection of ACTH stimulated a maximal increase in the serum concentration of corticosterone within 60 to 65 min. This increase was closely paralleled by the amount of corticosterone which was bound to cytoplasmic and nuclear fractions of chicken bursal cells.

Anal sucking-like movements and the uptake of tracer materials by the bursa Fabricii, caeca and caecal tonsils were studied in chick embryos and chickens of various ages. In embryos, aged 15 days or more, sucking movements were associated with transportation of colloidal carbon from the anal lips into the bursal lumen. Since sucking was found only after mechanical irritation of the skin, occurring simultaneously with slow respiratory efforts, we conclude that it may not have any biological importance during the embryonal period. After hatching, the sucking movements were spontaneous and occurred also in old chickens after bursal involution. In young chickens movements were simultaneous with the respiratory motions, increasing in older birds. In chickens with intact bursa, anal sucking was associated with effective transport of tracer materials into the bursal lumen, immediately after application; later the tracers were found in the caecal lumina. Also in old chickens, after bursal involution, the tracers were taken up into the cloaca, colon and the caeca. As in the bursa, a further transport of colloidal carbon from the lumen into the mucosal lymphoid tissue was found also in the caecal tonsils, but in the bursa this transport was by far more effective.

Summary The action in vivo of phytohaemagglutinin (PHA) on the thymus and bursa of Fabricius was investigated in 5 days old Studler-Cornish chickens. The PHA was administered i. m. in a dose of 3 mg. per 100 g. body weight and the birds were killed 8 and 24 hr, and 3, 7, 14 and 21 days thereafter. The action of PHA was evident at 7 days after administration when the thymus became stimulated (increase in weight, DNA and RNA content), but there was no effect on the bursa of Fabricius. The effect suggests that PHA has implications in cellular immunity. The thymus changes may be the result of the adrenal reaction. Zusammenfassung In-vivo-Effekt von Phytohamagglutin auf den Thymus und die Bursa Fabricii Bei 5 Tage alten Studler-Cornish-Kuken wurde der Einflus von Phytohamagglutinin (PHA) auf den Thymus und die Bursa Fabricii untersucht. Das PHA wurde in einer Dosis von 3 mg / 100 g Korpergewicht i. m. appliziert. Die Versuchstiere wurden 8 und 24 Stunden bzw. 3, 7, 14 und 21 Tage nach der Medikation getotet. Der PHA-Effekt wurde 7 Tage nach der Behandlung manifest, und zwar in Form einer Thymusstimulation (Zunahme des Gewichts sowie des DNS- und RNS-Gehaltes). An der Bursa Fabricii war kein Effekt festzustellen. Die Ergebnisse sprechen fur einen Einflus des PHA auf die zellulare Immunitat. Die Thymusveranderungen durften die Folge einer Nebennierenreaktion sein. Resume Effet in vivo de la phytohemagglutinine sur le thymus et la bourse de Fabricius On a examine l'influence de la phytohemagglutinine (PHA) sur le thymus et la bourse de Fabricius chez des poussins Studler-Cornish âges de 5 jours. PHA fut applique a une dose de 3 mg / 100 g de poids i/m. Les animaux furent sacrifies 8 et 24 heures, 3, 7, 14 et 21 jours apres l'application d'une stimulation du thymus (augmentation du poids et du taux en DNA et RNA). Il n'y a pas eu d'effet sur la bourse de Fabricius. Les resultats indiquent une influence de PHA sur l'immunite cellulaire. Les modifications du thymus devraient etre la consequence d'une reaction des surrenales. Resumen Efecto in vivo de fitohemaglutinina sobre el timo y la bolsa de Fabricio en pollitos Se estudio en pollitos Studler-Cornish, de 5 dias de edad, el influjo de fitohemaglutinina (FHA) sobre el timo y la bolsa de Fabricio. Se administro la FHA por via im. en una dosis de 3 mg/100 g peso vivo. Los animales de ensayo se mataron 8 y 24 horas resp. 3, 7, 14 y 21 dias tras la medicacion. La accion de la FHA se manifesto a los 7 dias del tratamiento, habiendose estimulado el timo (aumento del peso y de los contenidos en ADN y ARN). En la bolsa de Fabricio no se pudo apreciar ningun efecto. Los resultados abogan a favor de que la FHA tiene inferencias en la inmunidad celular. Las modificaciones en el timo podrian ser el resultado de la reaccion adrenal.

Four live virus vaccines against Infectious Bursal Disease (IBD) were studied with regard to their safety, immune response and applicability. None of the vaccines caused clinical symptoms or had an adverse impact on bodyweight. Differences between these vaccines were observed in their effect on the Bursa/Bodyweight Ratio and the severity of the microscopical lesions of the bursa Fabricii. The immunosuppressive effect of IBD vaccination at one day of age on the response to Newcastle disease vaccine applied was rather low. Three of the four vaccines induced antibodies associated with protection against challenge. Vaccination of SPF rearing chickens by drinking water at an age of 15 weeks produced an antibody response (Agar Gel Precipitin Test) whereas at 15 weeks produced an antibody response (Agar Gel Precipitin Test) whereas at an age of 23, 32 and 60 weeks it did not. Chickens of all age groups responded serologically to an intramuscular vaccination. A correlation was found between the immunological response and the effect of the vaccines on the bursa Fabricii.

Tubuloreticular structures were observed in bursal lymphocytes of a 12-day-old male chicken. These structures are often observed in mammalian lymphocytes and endothelial cells. Their presence in bursal lymphocytes confirm their association with B-lymphocytes.

Summary The findings are presented of a number of investigations, recorded elsewhere, carried out by the author and showing that in vitamin A deficiency in chickens, in addition to the metaplastic changes known so far in the conjunctiva and in the epithelium of the apper digestive and respiratory tracts, metaplastic processes also occur in other parts of the bird. As a result of this the appearance is observed of a stratified squamous, keratinizing epithelium, both in the surface epithelium and the follicles of the bursa of Fabricius and in the surface epithelium and the glands of the cloaca, in the epithelium of the vagina of the oviduct, the ureters, the collecting tubules of the kidneys, as well as in the epithelium of the parathyroid glands. The metaplastic changes in the epithelium of the ureters leads to the partial or complete obstruction of the urate outflow toward the cloaca, which may be the immediate cause of the occurrence of uratic diathesis (gout) in chickens in cases of vitamin A deficiency. On the basis of the established pathological pattern the lesions observed in the glands of the oesophagus and the oral mucosa in A avitaminosis in chickens are divided into three stages: (1) the onset of the disease; (2) more advanced form of deficiency; and (3) very marked deficiency, the time interval between the stages being about two weeks. Zusammenfassung Ein Beitrag zur Pathomorphologie des Vitamin-A-Mangels beim Huhn Die Ergebnisse einer Reihe fruherer, vom Autor durchgefuhrten, Untersuchungen uber den Vitamin A-Mangel bei Huhnern zeigten, das neben den bisher bekannten metaplastischen Veranderungen in der Konjunctiva und im Epithel der oberen Verdauungs- und Atemwege noch zusatzliche Veranderungen in anderen Teilen des Vogelkorpers auftreten. Diese Veranderungen in Form eines geschichteten, squamosen, verhornenden Epithels fanden sich im Oberflachenepithel und in den Follikeln der Bursa Fabricii, im Oberflachenepithel und in den Drusen der Kloake, im Epithel der Vagina des Eileiters, im Ureter, in den Sammelrohren der Niere und im Epithel der Nebenschilddrusen. Die metaplastischen Veranderungen im Epithel der Ureter fuhren zu einer teilweisen oder vollstandigen Behinderung der Uratabgabe in die Kloake. Dieser Vorgang konnte die direkte Ursache der bei der Vitamin A-Avitaminose bekannten Nierengicht der Huhner sein. Nach den immer wieder vorkommenden Mustern derpathologischen Veranderungen bei der Erkrankung der Huhner an Vitamin A-Mangel konnen die Vorgange in den Drusen des Oesophags und der Mundschleimhaut in drei Stadien eingeteilt werden: 1. Beginn der Krankheit, 2. fortgeschrittene Mangelerscheinungen und 3. sehr ausgepragte Mangelerscheinungen. Der Zeitraum zwischen den einzelnen Stadien betragt etwa zwei Wochen. Resume Une contribution a la morphopathologie de la carence en vitamine A chez les poulets Les resultats d'une serie d'examens anterieurs, effectues par l'auteur, sur la carence en vitamine A chez les poulets montrent qu'outre les modifications metaplasiques de la conjonctive et de l'epithelium des voies respiratoires et digestives superieures, connues jusqu'ici, on observait encore des modifications dans d'autres parties de l'organisme de l'oiseau. On trouve ces modifications, sous forme d'un epithelium stratifie, squameux et keratinise, dans l'epithelium superficiel et dans les follicules de la bourse de Fabrice, dans l'epithelium superficiel et dans les glandes du cloaque, dans l'epithelium du vagin de l'oviducte, des ureteres et des tubes collecteurs des reins et dans l'epithelium des parathyroides. Les modifications metaplasiques de l'epithelium des ureteres provoquent une inhibition partielle ou totale du passage des urates dans le cloaque. Ce processus pourrait etre la cause directe de la goutte renale connue dans les cas de carence en vitamine A chez les poulets. D'apres le schema des modifications pathologiques observees chez les poulets atteints d'une carence en vitamine A, on peut subdiviser en trois stades l'evolution des modifications dans les glandes oesophagiennes et de la muqueuse buccale: 1) debut de la maladie, 2) manifestations de carence avancees, 3) manifestations de carence prononcees. L'intervalle entre les differents stades est d'env. deux semaines. Resumen Una contribucion a la patomorfologia de la deficiencia de vitamina A en pollitos Los hallazgos de una serie de investigaciones realizadas con anterioridad por el autor, sobre la deficiencia de vitamina A en gallinas, mostraban que, en adicion a los cambios metaplasticos conocidos hasta la fecha en la conjuntiva y en el epitelio de las vias digestivas superiores y respiratorias, aparecen procesos metaplasticos en otras partes del ave. Estas alteraciones en forma de un epitelio estratificado, escamoso, queratinizante, se hallaron en el epitelio superficial y en los foliculos de la bolsa de Fabricio, en el epitelio superficial y en las glandulas de la cloaca, en el epitelio de la vagina del oviducto, en el ureter, en los tubulos colectores de los rinones y en el epitelio de las glandulas paratiroideas. Los cambios metaplasticos en el epitelio de los ureteres conducen a la obstruccion parcial o completa de la cesion de urato hacia la cloaca. Este proceso podria ser la causa inmediata de la conocida diatesis uratica de las gallinas en la deficiencia de vitamina A. Sobre la base de las muestras de lesiones patologicas establecidas en las gallinas enfermas de avitaminosis A, se pueden dividir los procesos registrados en las glandulas del esofago y de la mucosa oral en tres estadios: 1) comienzo de la enfermedad, 2) forma mas avanzada de los sintomas eficitarios, y 3) deficiencia muy acusada. El intervalo de tiempo entre los distintos estadios es de unas dos semanas.

Previous studies have shown both thymus and bursa cells to activate a pre-existing competence in adult lymphoid cells, probably by means of a humoral factor, Klopstock and Sharon (1965), Miller (1965), Small and Trainin (1967). Rather than using intact cells as inducers we were interested in finding out whether an extract of thymus or bursa cells could be shown to activate immunologically immature cells. For this purpose, two sorts of inactive cells, Simonsen (1965), Burnet and Burnet (1960) were chosen: 1. chick embryo bone marrow cells 2. chick embryo lymphoid cells To measure the immunologic competence of these cells, following their expected activation by extract from bursa and/or thymus cells, we decided to use the Simonsen CAM phenomenon, Cock and Simonsen (1958). The Simonsen phenomenon, as is known, entails the production of focal lesions on the chorio-allantoic membrane (CAM) of chick embryos upon placement on the membrane of immunologically competent…

Summary Surgical removal of the bursa of Fabricius in chicks at the age of 24 hours lowers their immunohumoral reactivity to spirochetes. Later removal of the bursa, at the 35th day, does not exert such an effect. Removal of the bursa increases the susceptibility of chicks to spirochetosis. Zusammenfassung Bedeutung der Bursa Fabricii bei der Immunitat gegen Geflugelspirochatose Die chirurgische Entfernung der Bursa F. bei 24 Stunden alten Kuken vermindert die immunohumorale Reaktivitat gegenuber Spirochaten. Wird die Bursa erst am 35. Tage entfernt, so hat dies keinen derartigen Effekt. Die Entfernung der Bursa steigert die Empfanglichkeit der Huhner gegenuber Spirochatose. Resume Importance de la bursa fabricii dans l'immunite contre la spirochetose aviaire L'ablation de la bursa fabricii chez des poussins âges de 24 heures affaiblit la reaction immunohumorale contre les spirochetes. Un tel effet n'est pas observe, si l'on supprime la bursa au 35ieme jour. L'ablation de la bursa augmente la receptivite de la poule a la sprirochetose. Resumen Significado de la bolsa de Fabricio en la inmunidad frente a la espiroquetosis aviar La ablacion quirurgica de la bolsa de Fabricio en pollos de 24 horas de edad disminuye su reactividad inmunohumoral frente a las espiroquetas. Sie se extirpa la mencionada bolsa el 35° dia, no surte tal efecto. La reseccion de la bolsa aumenta la susceptibilidad de los pollitos frente a la espiroquetosis.

Trachea, bursa of Fabricius, and small intestine of broilers 5 to 50 days of age from 10 flocks with varying levels of morbidity and mortality were screened for the presence of Cryptosporidium spp. Cryptosporidial oocysts were found in 24.2% of the examined birds. Avian Dis

SummaryLymphocytes located within the gut-epithelium of mammals, here called theliolymphocytes, are interesting but hitherto rather neglected. The kinetics of the theliolymphocytes suggests that they do not leave the organism together with the epithelial cells and that they may be part of a diffuse “primary lymphoid organ” comparable to the bursa Fabricii of birds. In this study it is shown that theliolymphocytes appear relatively late; there are as few as 0.5% in 2-week-old mice. A tenfold increase of theliolymphocytes occurs during the third week of life which might be correlated with immune responses which also appear at this time. Neonatal thymectomy causes a decrease of the number of theliolymphocytes in parallel with a decrease of the total number of blood lymphocytes. The latter finding, however, could be a consequence of wasting disease.