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We cultured the cervical lymph node lymphocytes of a patient suffering from cutaneous T-cell lymphoma. His anti-ATLV antibody was positive by indirect immunofluorescent method (IF). ATLV was detected on these cultured cells by IF. Type C particles were observed in the cultured cells by electron microscopy. These particles were measured to be 60 to 120 nm in diameter with electron dense core, and were considered as ATLV. This case showed a possibility of detecting ATLV by culture of lymph node lymphocytes from such a patient.

Four different types of neurons were identified in cultures of newborn rat neostriatum. Small and medium-sized neurons were most numerous. A few large neurons and some very small ‘microneurons’ were observed. The morphology of medium-sized neurons varied, and this group may contain more than one functional subgroup. Axosomatic synapses were associated with all types of neurons, but most of them made contacts with medium-sized neurons. All axodendritic synapses made symmetrical contacts, with or without synaptic membrane thickenings. A great majority of terminal boutons contained small, round, clear vesicles. A few terminals with large pleomorphic clear vesicles were seen. Large granular vesicles were found in the peripheral cytoplasm of some medium-sized neurons, dendrites and axon terminals. No terminals contained exclusively large granular vesicles, but in some terminals they were more numerous than the small clear vesicles. The dense core of the large granular vesicles was resistant to reserpine treatment. Kainic acid did not cause specific degenerative changes. The presence of several morphologically distinct populations of neurons renders it possible to study the nature of these cells in different experimental conditions. Intrinsic neostriatal synaptic contacts appeared to be symmetrical, although it is possible that some of them have the capacity to develop asymmetrical contacts. The lack of effect of kainic acid may be explained by the early maturational stage of the cells or by the lack of extrinsic contacts. More functional studies are necessary before the usefulness of these cultures for investigating neostriatal function can be assessed.

Light and electron microscopic observations were carried out on the secretory granules of the labial gland of the lizard, Japalura polygonata polygonata. The results obtained are.1) Japalura polygonata polygonata has superior and inferior labial glands, which can be described as a branched tubular type.2) The glandular cells are arranged in a layer and appear to be columnar in shape.3) The secretory granules of the superior labial gland stain intensely with naphthol yellow S and iron hematoxylin and are weakly positive with PAS and alcian blue.4) The secretory granules of the superior labial gland can be divided into two types when examined with the electron microscope. One is of moderate electron density, while the other has a moderate dense core and a narrow less dense halo. The PA-methenamine silver method shows a positive reaction which is limited to the narrow halo of the latter granule.5) The secretory granules of the inferior labial gland except those of the acini which are oriented superolaterally in the lower lip stain intensely with PAS and alcian blue, and they are also slightly positive with naphthol yellow S and iron hematoxylin.6) The secretory granules of the inferior labial gland can be classified into six types by the degree of the electron density of their core and halo. One of these types has a tripartite structure. Almost all of the secretory granules are positive for the PA-methenamine silver reaction.These findings suggest that the superior and inferior labial glands of Japalura polygonata polygonata have different characteristics from each other, because the secretory granules of the superior labial gland mainly contain protein, while those of the inferior labial gland contain mucopolysaccharides.

The eosinophil was first discovered in 1846 and ever since it has been an object of curiosity and fascination to investigators. The literature on eosinophils is vast; Schwarz's review done in 1913 contains 1,200 references. Nonetheless knowledge of the structure and of the chemical composition of the cell has continued to grow and in the past decade a series of studies have disclosed new information. In this review certain of the more recent reports dealing with the structure and biochemistry of the eosinophil will be discussed. Cytoplasmic organelles of eosinophils The distinguishing feature of the eosinophil under the light microscope is the dense eosinophilic granulation which may completely fill the cytoplasm. When viewed under the electron microscope the eosinophil granule, as shown in Figure 1, is seen as a membrane bounded cytoplasmic organelle with a distinctive internal structure. In most cases, the eosinophil granule has an electron dense core and a less dense matrix.

The fine structure of a parathyroid carcinoma of high endocrine activity is described and compared to adenomas. There are some striking features especially concerning the Golgi apparatus. Non-membrane bound fine granular material and vesicles engulfing cytoplasmatic ground substance are seen at the outer surface of the Golgi stacks. A GERL like reticulum was observed with production of coated vesicles and dense bodies. Condensing vacuoles or prosecretory granules could never be demonstrated in the area of the Golgi complex. A smooth reticulum like network with an electron dense core connecting Golgi apparatus and granular endoplasmatic reticulum was shown to be present in about all cancer cells. This smooth reticulum is producing secretory granules by budding off, apparently taking over the function of the condensing vacuoles of the Golgi apparatus.

A strumal carcinoid arising in a benign cystic teratoma of the right ovary was reported in a 40-year-old woman. The solid tumor was histologically a trabecular carcinoid tumor associated intimately with thyroid follicle-like structures. By electron microscopy, spherical dense core secretory granules were found in the cytoplasm of tumor cells. Final diagnosis of strumal carcinoid, however, was established in the present tumor by the immunohistological confirmation of thyroid tissue with anti-human thyroglobulin.

The soft membrane fibres of the turtle eggshell like their avian counterparts, consist of an electron dense core surrounded by a less dense mantle. In the oviposited egg the core material is homogeneously electron dense while in oviducal eggs it has a pitted appearance. Histochemical analyses indicate that as in the fowl, the fibres are a protein-carbohydrate complex.

Summary The fine structure of maize rough dwarf virus (MRDV) has been studied by examining particles in ultrathin sections, crude extracts, and in purified preparations from diseased plants. The virus has a diameter of 65 to 70 nm. and contains a dense core of about 40 to 50 nm. diameter that is enveloped by a thin inner capsid 3 nm across. The outer capsid is about 10 nm. wide and 18 holes are seen on the perimeter. Smaller particles, 40 to 50 nm. in diameter are found in all types of preparations and some have incomplete outer capsids consisting of 12 isolated projecting structures that adhere to the inner capsids. Purified preparations contained only the incomplete particles. The structure of MRDV particles is compared to that of reoviruses.

Rabbit kidney cells (RK-13) infected with rubella virus develop, at days 7 and 8, cytoplasmic basophilic inclusions referred to typical complexes of annulate lamellae (AL) and radial cisternae (RC). Beside them are found spherical structures 920 A in diameter. These particles seem to develop from stacks of RC, in which transition stages of this hypothetical process are detectable. These particles cannot be considered AL in cross section. Another type of spherical structure, 1000–2000 A in diameter, is concomitantly present near the above-mentioned figures. They are composed of a central dense core and an enveloping membrane. The occurrence of numerous syncytial cells is also observed. A hypothetical relationship of the development between the two types of particles is given, as well as their relation with rubella virus infection.

This paper reports details of the development of the external layer of the median eminence with special reference to the appearance of the nerve terminals, containing electron dense core and electron lucent vesicles, in the outermost layer of a palisade structure (2–3 μ thick). Observations were made on perinatal rats of the Sprague-Dawley strain (16, 18, 20 day fetuses and rats 5 hours, one 4, and 8 days after birth). The palisade structure of the outermost layer of the median eminence was first clearly detectable 5 hours after birth. Concomitantly, there was a marked increase in the number of nerve terminals in this layer. The nerve terminals containing electron dense core and electron lucent vesicles were seen in 18 day fetuses in the outermost layer of the median eminence. These nerve terminals increased in number during development, especially from the 20th day of fetal life to the 4th day after birth. The size range of the majority of the electron lucent vesicles did not change during development, but that of the core vesicles increased from 600–800 A from the 18th to 20th day of fetal life. The initiation of neurohemal control of the adenohypophysial function by the hypothalamus is discussed.

Electron microscopic study of nucleated erythrocytes of the goldfish, Carassius auratus, reveals the microtubular elements comprising the marginal band which encircles the cell. Six to ten units are visible at each pole of the cell, immediately within the plasmalemma. Each tubular unit is composed of an electron dense membrane enclosing a less dense core. Cross-sectional units average 264 A outer diameter, whereas tubules measured in longitudinal sections average 237 A.

Endosperm protein bodies are membrane bound. Internally, each body shows a pattern of dark and light concentric layers. A median dense core may also be present. These bodies stain for protein with mercuric bromphenol blue, but not for acid phosphatase.

Numerous microtubules of nerve cells and gliocytes in the toad are found, in electron micrographs, to contain a dense core. Such content is granular in nature, the granules being irregularly disposed in the lumen of the microtubules. Comparative observations on dense-core microtubules in peripheral and central nerve cells indicate that they are consistent cell components in the entire nervous system of the toad. The functional significance of the granular content of the microtubles is discussed.

The development of the chloroplast of Aspidistra is similar to that of the Taraxacum chromatophore which has been described previously. The first stage observed is a small dense body situated in the protoplast near the cell wall. During growth it differentiates into two parts, one being the inner dense core and the other the surrounding layer of lighter material. The first sign of laminae is manifested as small outward folds of what appears to be some form of an envelope around the core. The grouping of discrete stacked lamina-formations seem to indicate that new laminae arise in connection with old ones. The “grana” consist of regularly arranged single lamellae which extend into the extra-granular regions where they become paired each double-sheet including some granular substance. At the point of emergence anastomoses often occur. The development and function of this laminar system is briefly discussed.

The ultrastructures of gray cells and archeocytes were studied in adult Microciona prolifera to aid in their identification in reaggregation masses. Gray cells were easily identified by their uniform, densely-stained granules and abundant glycogen particles. A small, dense nucleolus was occasionally observed. Archeocytes lacked the characteristic granules of the gray cell, and a large nucleolus with a less dense core was invariably found. To follow the stepwise formation and differentiation of the upper pinacoderm, pieces of sponge were squeezed through cloth into polyethylene dishes, and the resultant masses were fixed with 2% OsO4 in 90% sea water at 6, 12, 24, 48, and 96 hours after dissociation. Fixation, dehydration and embedding in the same dish preserved the orientation of the masses. Reaggregation masses of less than 150 μ diameter failed to differentiate a pinacoderm while in masses greater than 250 μ virtually the entire upper surface was composed of exopinacocytes by 96 hours. The gray cells and archeocytes were little changed from their structure in the intact sponge except for a more rounded shape and a greater number of phagosomes in the archeocytes. Cells forming the surface epithelium contained large nucleoli, phagosomes and other characteristics similar to those of archeocytes, while cell types intermediate between gray cells and exopinacocytes, were not observed. It was concluded that gray cells do not form exopinacocytes, and archeocytes form the nucleolated exopinacocytes.

In the myotomal muscles of the dogfish, Scyliorhinu canicula, there are 2 major types of fibre. The red fibres at the periphery of the myotome receive a distributed en grappe pattern of innervation. There are subjunctional folds at these endings, and the nerve terminals contain vesicles around 50 nm in diameter. In contrast to this, the white twitch fibres of the myotome are innervated focally, by 2 nerve fibres passing to the same motor end-plate. These 2 fibres contain vesicles of different types. One type of nerve terminal contains vesicles around 50 nm in diameter; these terminals resemble those upon the red fibres. The other contains vesicles up to 100 nm in diameter, frequently possessing a dense core. It is suggested that the white twitch fibres of dogfish are innervated by 2 separate axons, possibly containing different transmitter substances.

SummaryUltrathin sections of the pellets formed by ultracentrifugation of plasmas from birds with myeloblastosis and erythroblastosis have been examined by electron microscopy. In the material from both diseases there were observed structures of similar appearance represented by images of round or oval shape consisting centrally of a dense core of about 40 mμ diameter. These were surrounded by a less dense material and were limited by an outer membrane-like structure with a total particle diameter of about 80 mμ. In many instances the limiting membrane appeared to be double. The ultrastructure of these agents of the avian leukemic diseases was very similar, if not identical, to that of the viruses of other chicken neoplasms. No particles of these characteristics were obtained from the plasmas of apparently healthy chickens.

SummaryTumorous spleen from chickens with erythroblastosis RPL-12 strain were examined in ultrathin sections. The cytoplasm of cells of the affected spleens showed changes similar to those observed in visceral lymphomatosis. Characteristic particles were observed in cytoplasm of cells similar in structure and size to that of particles in visceral lymphomatosis. The diameter of the particles was found to vary from 650 A to 830 A, with an average of 730 A, and that of the internal dense core varied from 280 A to 380 A, with an average of 320 A. The average size of the characteristic particles in erythroblastosis RPL-12 strain and visceral lymphomatosis is similar and appears to be larger than that of similar particles in erythroblastosis “R” strain and granuloblastosis (myeloblastosis).

Dr. Harter demonstrated for us the structure of visna virus. I would like to elaborate this subject by pointing out the difference in size between the budding virus and the complete virus (Fig. 3A.1). The buds are almost twice the size of the complete virus. Serial sections reveal occasionally a cross-sectional view of the buds, which may falsely appear as detached virus. In reality, however, the majority of particles are not detached and we have hypothesized that the truly detached units have a very short life span and become quickly converted into the complete virus with its dense core. The development of a complete virus involves an intermediate stage during which the dense material appears in a crescent, but is later rearranged in its final form of dense core. Not all of these steps have become apparent and, somewhere in this process, a certain quantity of membrane material disappears.

This paper reviews talks and posters about star formation in our galaxy, presented in the first of the two weeks of this meeting. The topics covered in this paper are meeting quality (§ 2), completeness (§ 3), posters (§ 4), outflows and winds (§ 5), magnetic fields (§ 6), bimodal star formation (§ 7), and trends and prospects (§ 8).

Following subcutaneous injections of isoproterenol hydrochloride (ISO), atrial cells present a large number of partly degranulated or completely clear "specific granules" enclosed by an intact membrane. Such profiles were never encountered in normal controls and might suggest ISO-induced release of a secretory product. Permeability of perigranular membrane was tested using the extracellular macromolecular tracer horseradish peroxidase (HRP). Reaction product was entirely absent within granules of atrial cells in which the sarcolemma was made permeable to HRP molecules by the ISO injections. This seemed to be the case even in heavily labelled cells in which the peroxidase had penetrated the mitochondrial membranes. In atrial cells impermeable to the tracer, the specific granules closely apposed to the sarcolemma were always HRP-negative. The release mechanism of a possible secretory substance from the specific granules is discussed.

Fourteen mucinous ovarian cystadenomas of different grades of malignancy (7 benign, 4 borderline and 3 malignant) were investigated by electron microscopy. The main tumour cell type was a columnar mucous epithelial cell with short microvilli. With increasing grade of malignancy the shape and size of these cells became more irregular and the number of mucous granules in them decreased. Most of the mucous granules had a dense core and a less dense reticular component, which stained well with the periodic acid-silver methenamine (PASM) technique. Goblet cells with the usual ultrastructure were found rather frequently. The tumours in a given group of malignancy were relative similar to each other in their light and electron microscopic appearance. However, a number of tumours contained argyrophil and argentaffin cells in addition to the columnar and goblet cells. The findings of the present study support the view that the mucinous ovarian cystadenomas arise from the ovarian surface epithelium via a metaplastic process.

The fine structure of boar Leydig cells is re-examined in samples post-fixed with OsO4-K4Fe(CN)6, an elective method to preserve the ultra-structural detail of the endocrine testis. The cells show a pleomorphic arrangement of the smooth endoplasmic reticulum. Large “vesicle-like” dilatations are interspersed in the tubular network of this membrane system. The dilatations contain a flocculent material with a dense core and a dispersed peripheral rim. Additional features of boar Leydig cells revealed by OsO4-K4Fe(CN)6 treatment are parallel tubular arrays within residual bodies, and electron-lucent inclusions suggestive of crystals of cholesterol or its esters. These structural characteristics were not identified in previous electron-microscopic studies on Leydig cells of the boar or of other mammals. The unique components of boar interstitial cells described may be the morphological counterpart of the peculiar composition of testicular steroids secreted in this animal, namely low concentrations of androgens and large amounts of pheromones.

Large dense core vesicles (LDCV) were found frequently enough in normal guinea pig central white matter, basis pontis and spinal cord posterior columns to be regarded as a normal organelle. A review of studies of LDCV and dense core particles (DCP), which have a different cytological localization and appear to be associated with a variety of diseases, suggests that they are the same, and hence remarkably ubiquitous. LDCV should no longer be regarded as a type of synaptic vesicle, but as an incompletely defined organelle common to many cell types.

Gastrin cells in the pigeon, quail, gull and kite were identified at ultrastructural level by immunocytochemistry, using the consecutive semithin/ultrathin section technique. In contrast to the gastrin granules known in mammals, the avian gastrin granules generally contained a consistent dense core accompanied by a clear halo between the core and limiting membrane. The mean diameters of gastrin granules in the pigeon, quail, gull and kite were 211 +/- 37, 247 +/- 45, 331 +/- 61 and 353 +/- 73 nm respectively. The carnivorous birds seemed to possess larger gastrin granules than the grain-eating birds. The species differences in the size and fine structures of the gastrin granules were discussed.

The caudal part of the dorsomedial bed nucleus of the stria terminalis (BNST) contained a discrete region of dense substance P (SP) staining in both male and female rats. However, the pattern of this staining differed markedly between the sexes. Males exhibited a densely stained capsule surrounding a less dense core. In females, this core was barely detectable (small and present on only 1 or 2 sections) or absent. The perimeter of this area of dense staining was traced and the area inside calculated. The mean area was found to be 2.4 times larger in males. The component of the BNST which receives this SP innervation was identified on Cresyl violet-stained sections. The area occupied by this distinct cell group was 32% larger in males. The areas of the suprachiasmatic nuclei and whole coronal sections through the BNST were measured in the same way and found not to differ between the sexes.

Membrane specialisations have been found on neurones in embryos of the clawed toad Xenopus laevis. The specialisations have been called dense membrane knobs and consist of an outpushing of the plasma membrane with a slight increase in its density. The out-pushing forms a spherical knob with an amorphous dense core and a total diameter of 500 to 600 A. The knobs are found on axons and dendrites both in the spinal cord and peripherally.

The morphological and histochemical characteristics of endocrine-like cells of the pulmonary epithelium of the right lower lobe of 12 human adult lungs were studied. Few cells were reactive to the argyrophil silver method of Grimelius and of Sevier and Munger and cells with a similar morphology and distribution emitted a green or yellow fluorescence after treatment of the lung epithelium with the amine presursors L-DOPA or L-HTP, respectively. A greater number of cells seems to be demonstrated by electron microscopy. The cells were characterized by small, round secretory granules showing a central dense core and a very thin clear halo between the core and the surrounding membrane. The cells are thought to be related to the endocrine-like cells of the pulmonary epithelium of the human foetal lung and to cells of carcinoids of larger bronchi.

Two types of intranuclear inclusions were described in a brain biopsy from a patient with Creutzfeldt-Jakob disease. The first type of intranculear inclusion was papova virus-like and was observed within 20% of the nuclei of all astrocytes and neurons examined. The particles measured 32 nm in diameter and consisted of a dense core surrounded by a multi-layered shell. The second type of intranuclear inculsion was a granulo-fibrillar nuclear body found within the nuclei of astrocytes and neurons. The possible significance of these inculsions to the etiology of Creutzfeldt-Jakob disease is discussed.

Two kinds of virus-like particles, doughnut-shaped particles and particles with dense core, were discovered in a brain tissue from a patient with Creutz-feldt-Jakob disease. The two types of virus-like particles are similar to immature type C and type C particles. Although no direct relationship between Creutzfeldt-Jakob disease and these virus-like particles can be established, these facts may suggest that viruses play some role in the pathogenesis of Creutzfeldt-Jakob disease.

Numerous inclusion bodies (virus-like particles) were observed in the lumina of the intercellular canaliculi, mucous tubules and intralobular ducts of the opossum submandibular gland. The particles are spherical in outline, show an electron dense core, and are surrounded by a peripheral membrane.

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.

An electron microscopic study of intracellular Penicillium chrysogenum virus showed virus particles with a dense core distributed as individuals or aggregates in cytoplasm and/or in vacuoles of mycelial cells. In cytoplasm the virus particles were often near, but not in, the nucleus. Electron-dense regions of granular appearance enclosed more complete virus particles in some cells. Lipid bodies, vacuoles, and membranous structures were often prominent in infected cells. Sometimes cylindrical arrays of virus particles occurred in vacuoles and also in degenerated cells. Aberrations consisting of various degrees of degeneration or disappearance of cytoplasm and cellular organelles were often observed in aged cells with large quantities of virus. The virus particles sometimes released fibrous material forming networks from their core region.

The fine structure of rabbit adrenal chromaffin cells was examined prior to, and at various times after, hypoglycemic stress-induced release of catecholamines. At the time of maximum catecholamine depletion, 12 hr after insulin-induced hypoglycemic stress, the ratio of electron translucent vesicles to total vesicles was greatest. Return of this ratio to control values occurred when catecholamine levels returned to prestimulation values. Likewise, the ratio of dense core vesicles to total vesicles decreased as the catecholamine level decreased and returned to control values concomitantly with the return of the catecholamines to their prestimulation levels. A rise in the ratio of dense core microvesicles to translucent microvesicles when the catecholamine levels are returning to their prestimulation values suggests that the dense core microvesicles may represent vesicles in the process of synthesizing or accumulating catecholamines. It is concluded that the translucent vesicles arise from dense core chromaffin vesicles and decrease in number as the catecholamine stores are replenished.

Agitation of live cells in 10% ethanol produced a loosening of cortical cytoplasm and mass release of axopodia from their anchorages. A balloon-like swelling quickly formed at the proximal end and, about 15 min after detachment, at points along the axopodium. The dense core shaft, presumably the axoneme, was still visible under phase contrast shortly after detachment, but it dissolved within 30 min. The detached axopodia did not change in appearance, however, when the medium included 0.6 mM MgSO4, 1 mM GTP, and 50–150 mM EGTA, pH 7, at either room temperature or 4 °C. This procedure can serve as a starting point for combined biochemical-ultrastructural investigation of these axopodia and the unique characteristics of their microtubules.

A case of bronchial carcinoid with filamentous aggregates is described. The cytoplasmic inclusions were clearly demonstrated by means of Masson's trichrome stain in Bouin's fixed tissue, and the neoplastic cells showed a spontaneous green fluorescence with ultraviolet light. Electron microscopic examination showed that the inclusion bodies were composed of aggregates of filaments measuring 10A. They were located in the juxtanuclear region in close relation with mitochondria and the cisternae of the Golgi system. There were many neurosecretory granules inside the aggregates of filaments, some showing alterations in the dense core. From this data, we concluded that the aggregates seemed to represent an active rather than an involutional phenomenon and that their relation with hypoxemia and humoral influences needs further study. Cancer 46:144–151, 1980.

Neuromuscular junctions on leech body wall muscle have been described. Based on vesicle morphology, there are two types of junctions, (I) clear vesicle terminals, and (II) dense core vesicle terminals. Further, the dense core terminals are-of two types, (1) small terminals which appear to directly innervate body wall muscle cells, and (2) large terminals which appear to synapse on clear vesicle terminals which in turn innervate body wall muscle cells. The clear vesicle ending resembles known cholinergic junctions in other systems. The cores in the dense core vesicle terminals are regarded as containing 5-HT because (1) they are structurally identical with the 5-HT containing cores in granules of the Retzius cells, (2) they contain a chromaffin substance, and (3) they become radioactive when tritiated 5-HT is present but not when 5-HTP or noradrenaline is present.

Infection with pseudorabies (Pr) virus of cells treated with 5-fluorouracil (FU) results in the formation of syncytia indistinguishable from those formed by normal cells after infection; small, multiple intranuclear inclusions are also formed, but these, unlike the inclusions in infected untreated cells, do not become Feulgen positive. FU-treated cells produce noninfective virus particles, the external structure of which can not be distinguished from that of the particles produced by untreated cells, but from which the central electron dense core normally present is missing. The morphology of Pr virus particles as observed after staining by the negative contrast method is described.

The NASA science program includes several major areas of research in which our efforts will be concentrated during the next ten years. They include studies of the earth, its atmosphere, disturbances on the sun and the effect they produce on the earth, investigations of the moon and the nearby planets, and studies of the stars and galaxies.

The effects of constricting post-ganglionic sympathetic nerves have been studied in the cat splenic nerve and guinea-pig hypogastric nerve. The results obtained using a fluorescence method for the histochemical localization of noradrenaline have been compared with electron microscopic findings. A close correlation was found between the accumulation of fluorescent material, attributable to noradrenaline, and of vesicles with an electron dense core (granular vesicles) believed to contain noradrenaline, proximal to the constriction in these nerves. This accumulation of noradrenaline was visible by 1 h after operation and increased rapidly in amount during the succeeding hours. It apparently reached a maximum after approximately 2 days and was found in what appeared to be newly formed axons 3 to 4 days after operation. Reserpine reduces the fluorescence and the number of vesicles with electron dense cores which accumulate proximal to the constriction. It is suggested, (1) that the fluorescent material is due, at least in part, to the presence of the granular vesicles, and (2) that the constriction has blocked the normal proximo-distal movement of noradrenaline which is believed to occur in post-ganglionic sympathetic axons.

The antennae of Arenivaga have six types of chemoreceptor sensilla. Some of these have unusual morphological features which may be adaptations for survival in a dry habitat. The sensory dendrites are well protected by cuticular structures, and in some receptors stimulatory molecules must pass through long channels or through pores filled with strands to reach the sensory cells. Large grooved pegs (possibly pheromone receptors) are numerous on antennae of adult males, and grooved sensilla are described here in detail for the first time. Thin-walled pegs, present in males and females, do not have pore tubules or hollow filaments as observed in many other insects. Rather, they contain structures designated here as pore strands, since they have a dense core rather than a light center as previously described for pore tubules and filaments. These strands do not appear to be evaginations of the dendritic membrane, but are probably formed in association with the cuticular structures of the sensilla.

SummaryUltrathin sections of tumorous spleen and liver from chickens of the so-called line 15 with erythroblastosis have been examined in the electron microscope. In cells of these organs spherical or spheroid structures were observed, composed of a central dense core of about 260 A, surrounded by a less dense material and limited by an outer membrane, varying in diameter from 570 A to 760 A. The structure of these particles resembles that of particles described in other tumors of chickens and in other tumors of known viral origin. No particles of similar character were observed in cells of organs from control healthy chickens.

SUMMARY Neural lobe neurosecretory granules (NSG) have been studied after different fixation procedures. When the pH of prefixation in a triple-aldehyde solution was varied, the dense core of NSG's was best preserved at pH's 5·0 and 6·0 but at pH's 7·0 and 8·0 loss of density of the granule core occurred and was most marked at pH 8·0. Increased duration of prefixation resulted in progressive loss of density of the granule core at pH's 7·0, 7·3 and 8·0, but at pH's 5·0 and 6·0 granules remained dense-cored, even after 24 h prefixation. When osmium tetroxide was used alone as a fixative, dense cores were again best preserved at acidic pH. This finding was correlated with studies in vitro in which the fixative solutions were reacted with aqueous suspensions of known components of the NSG's. The neural lobes of animals stimulated to release hormone by substitution of 2% NaCl solution for drinking water were also studied after fixation at different pH's. There was a significant decrease in the number of NSG's after treatment but no significant decrease in the proportion of NSG's which retained the dense-cored appearance at any pH. This suggests that hormone loss from the neural lobe is associated with loss of entire granules rather than with a reduction of density of the granule core and this finding is discussed in the light of theories on the mechanism of hormone release.

Unbefruchtete Eier der TunikatenAscidia nigra (selbstfertil) undCiona intestinalis (selbststeril) wurden elektronenmikroskopisch untersucht. Quantitative, nicht aber qualitative Unterschiede wurden in der Feinstruktur der Eizellen der beiden Arten gefunden.

MANY authors1–5 consider that the insoluble, fluorescent pigments originating from oxidized unsaturated lipids are primary or secondary factors in the onset and evolution of several diseases, and vitamin E deficiency in man and animals is frequently associated with ceroid pigment1,5–8. In 1961, Geer et al.9 observed dense cytoplasmic inclusions in electron micrographs of atherosclerotic lesions and coronary endothelial cells. The inclusions had a dense core and showed knife striations; during processing they often shattered or dropped out of the section. Geer et al. suggested that these might be some form of hard material. Gyorkey et al.10 have observed crystalline structures similar to those to be described here in electron micrographs of ceroid isolated from human arteries.

SummaryTumorous spleens and livers from chickens with granuloblastosis were examined in ultrathin sections. In the cytoplasm of the affected cells changes were observed similar to those seen in erythroblastosis, another member of the fowl leukosis complex. Particles were observed in the cytoplasm of cells of similar size and structure to that of particles in erythroblastosis. Average total diameter of the particles was found to be 670 A and that of the central dense core was 260 A. No particles of similar size or structure were observed in ultrathin sections of organs from young healthy chickens of similar breed.

The compression or severance of an axon results in important ultrastructural changes at the regenerating segment. While in a normal myelinated axon only less than 1% of the volume is occupied by axially oriented material composed of neurotubules and neurofilaments (De Robertis and Franchi, 1953 ; Thornburg and De Robertis, 1956) after sectioning the proximal stump becomes loaded with mitochondria, neurotubules and numerous clear and dense core (i.e. granulated) vesicles (for lit. see Lubinska, 1964; Pellegrino DE Iraldi and De Robertis, 1968).

Young massive clusters (YMCs) have central stellar mass surface densities exceeding $10^{4} M_{\odot} pc^{-2}$. It is currently unknown whether the stars formed at such high (proto)stellar densities. We compile a sample of gas clouds in the Galaxy which have sufficient gas mass within a radius of a few parsecs to form a YMC, and compare their radial gas mass distributions to the stellar mass distribution of Galactic YMCs. We find that the gas in the progenitor clouds is distributed differently than the stars in YMCs. The mass surface density profiles of the gas clouds are generally shallower than the stellar mass surface density profiles of the YMCs, which are characterised by prominent dense core regions with radii ~ 0.1 pc, followed by a power-law tail. On the scale of YMC core radii, we find that there are no known clouds with significantly more mass in their central regions when compared to Galactic YMCs. Additionally, we find that models in which stars form from very dense initial conditions require surface densities that are generally higher than those seen in the known candidate YMC progenitor clouds. Our results show that the quiescent, less evolved clouds contain less mass in their central regions than in the highly star-forming clouds. This suggests an evolutionary trend in which clouds continue to accumulate mass towards their centres after the onset of star formation. We conclude that a conveyor-belt scenario for YMC formation is consistent with the current sample of Galactic YMCs and their progenitor clouds., Comment: 11 pages, 4 figures, 4 tables. Accepted for publication in MNRAS