Distribution and structure of the adrenocortical homologue in the garpike

The microanatomy of the yellow corpuscles (adrenocortical homologue, AH) in the holostean fish, Lepisosteus spp., was studied by serial sectioning, steroid histochemistry, and electron microscopy. The modification of this tissue to short-term ACTH treatment was also observed. The distribution of the AH within the renal tissue of the garpike phylogenetically represents a more advanced condition than that seen in its closest holostean relative, the bowfin, and appears to approximate that in teleosts. The homology of this tissue to vertebrate adrenocortical tissue was established by the positive identification of the enzyme, Δ5-3β-hydroxysteroid dehydrogenase, and by the ultrastructural features of the cells before and after ACTH administration. The AH cells possess fine structural features characteristic of steroidogenic cells, namely, polymorphic mitochondria with tubular cristae, abundant tubules of smooth endoplasmic reticulum, a prominent Golgi complex, and lipid droplets. Other interesting features include the presence of annulate lamellae and a variety of dense bodies. Digitonin perfusion results in the deposition of presumed, cholesterol-digitonide crystalline spicules on the surface microplicae of the cells and as dense accumulations in association with smooth endoplasmic reticulum. ACTH administration results in swelling of mitochondria, a loss of their cristae, and a decrease in electron density of their matrices. Alterations also occur in the smooth and rough endoplasmic reticulum, and large osmiophilic inclusions of irregular profile appear. Some of the ACTH-induced modifications are similar to those observed in the adrenocortical cells of other vertebrate groups following comparable stimulation.     

Fine structure of a virilizing adrenocortical adenoma.

An adrenocortical adenoma associated with adrenogenital syndrome in a two-year-old boy was investigated light and electron microscopically. Urinary 17-ketosteroid excretion was considerably elevated and unresponsive to dexamethasone administration. The level returned to normal after surgical removal of the tumour. Adenomatous cells display striking cellular and nuclear pleomorphism. Megalocytes with huge nuclei and nucleoli frequently occur. Deep cytoplasmic indentations cause nuclear pseudoinclusions and bizarre shape of the nuclei. True nuclear inclusions are also seen, as well as nuclear fragmentation. Cytoplasmic organelles show striking morphological alterations. Mitochondria with lamellar and tubular cristae are transformed into round or ovoid organelles of vesicular type. Their internal compartment is reduced, matrix material increases relatively, and mitochondrial inclusion bodies develop. Mitochondrial inclusions are identified as corresponding to fuchsinophil (siderophil or argyrophil) granules seen in the light microscope. Their staining properties indicate their glycoprotein nature. Vesicular profiles of smooth endoplasmic reticulum predominate and stacks of rough endoplasmic reticulum are transformed into tubules and vesicles. In Golgi regions, only vesicular elements are enriched. Lipid droplets are scarce. It was not possible to demonstrate histochemically catalase activity in microbodies. Dense bodies only occur in small, undifferentiated tumour cells. Multivesicular bodies, autophagosomes and residual bodies are rare. Lipofuscin is absent. Tumour cells are thought to derive from a population of undifferentiated cells ("germinative tumour cells"). Their morphological features and organelle equipment during a hypothetical course of differentiation and following dedifferentiation is described and discussed with respect to exceeding androgen synthesis.     

Fine structure of adrenocortical cells in adult male rhesus monkeys

Adrenals of ten mature male rhesus monkeys were studied by electron microscopy. Mitochondria had lamelliform cristae in the zona glomerulosa and tubular cristae in the zona fasciculata and zona reticularis. Agranular reticulum of tubular form was scarce in the zona glomerulosa but present in great abundance in the fasciculata and reticularis. The Golgi complex was prominent in the cells of the zona glomerulosa but poorly developed in the cells of the inner cortical zones. Zona fasciculata cells contained large, highly ordered “stacks” of granular endoplasmic reticulum which showed multiple connections with the random network of tubular agranular reticulum. In the reticularis, granular endoplasmic reticulum was present in more disordered, whorl-like arrays. Lipid droplets in the inner cortical regions were enveloped by tubules of agranular endoplasmic reticulum. Occasional sections showed these tubules ending blindly at or near the surface of the lipid droplets. This association was strongly suggestive of a functional relationship. Dense bodies varied in size and complexity of structure throughout the cortex. They were smallest and simplest in form in the zona glomerulosa; those in the zona reticularis were the largest and most complex.     

Fine structural study of postcastrational adrenocortical carcinomas in female CE-mice

Postcastrational adrenocortical carcinomas in the CE/Ki inbred strain of mice and the adrenals of noncastrated CE/Ki mice were studied using light and electron microscopic techniques. Most of the tumors appeared as large nodules of cells separated by septae comprised of collagen and blood sinusoids. The majority of tumor cells (Type 1) showed few or no lipid droplets (sudanophobic), polymorphic hyperchromatic nuclei, lack of SER, abundant RER and free ribosomes, prominent Golgi complexes, and few mitochondria with scant internal membranes. Clusters of Type 1 cells were surrounded by a basal lamina. In contrast, Type 2 cells revealed abundant and dilated tubules of SER, large number of lipid droplets and mitochondria with tubulovesicular cristae. These results suggest that Type 2 cells were probably active in steroid hormone synthesis and secretion while Type 1 cells were highly anaplastic and apparently non-steroid-secreting cells.     

Fine structural modifications of the rat chromatoid body during spermiogenesis

The chromatoid body of rat spermatocytes and spermatids was studied with routine electron microscopy and the PA-silver method for detection of glycoproteins. The chromatoid body consists of a membrane-free aggregate of electron dense, finely filamentous material, in association with small vesicles. In late pachytene spermatocytes, there may be more than one chromatoid body; its dense component is diffusely reticulated. In young spermatids, there is only one chromatoid body per cell; the dense component is fairly compact, but it encloses less dense areas continuous with the cytoplasm. Within the less dense areas, as well as at the periphery of the dense component, small (400–800 Å) oval or tubular vesicular structures are observed whose contents exhibit a positive reaction for glycoprotein in PA-silver stained sections. When the spermatid nucleus begins to elongate, the chromatoid body takes the form of an arc around the axial filament proximal to the centriolar apparatus. Soon thereafter, the bulk of the chromatoid body condenses into a sphere of very dense filamentous material surrounded by a corona of enlarged glycoprotein-containing vesicles. In the later stages of spermiogenesis, the chromatoid body migrates away from the nucleus and disintegrates by fragmentation. It is noted that the chromatoid body undergoes its major morphological changes, possibly indicative of its active phase, while located in the para-centriolar region, at the time when the nucleus elongates, and the connecting piece and ring of the spermatid are formed.     

Retinal fine structure in the European eel Anguilla anguilla. IV. Photoreceptors of the yellow eel stage

The complex life cycle of the European eel (Anguilla anguilla) involves a long catadromous migration during which the eye undergoes a number of morphological alterations. This report deals with the fine structure of the photoreceptors of the yellow eel stage and is part of a comparative study of the retina of the eel during the major stages of its life cycle. The photoreceptors of the yellow eel are easily divisible into rods and single cones and the rods at least appear to be capable of retinomotor responses. Rods are more elongated and more numerous than cones. In the light-adapted state the inner segment of rods is of the same diameter as the outer segment but narrows abruptly in the myoid region. Cone inner segments on the other hand are much wider than the outer segments which taper distally. Both rods and cones display organelles in the inner segment indicative of high metabolic activity. Cone nuclei are located scleral to the external limiting membrane while rod nuclei are vitreal to this boundary. Both rods and cones display both invaginated and superficial synaptic sites. Except for an apparent increase in number and outer segment width of the rods, the photoreceptors of the yellow eel have changed only slightly from that described for the glass eel stage.     

Retinal fine structure in the european eel Anguilla anguilla. II. Photoreceptors of the glass eel stage

The eye of the European eel (Anguilla anguilla) undergoes marked morphological changes during its long and complex life cycle. This report describes the fine structure of the photoreceptors of the glass eel stage and forms part of a comparative study of the retina of the eel during the major stages of its life cycle. The photoreceptors of the glass eels are readily divisible into rods and cones based on morphological criteria. Rods are more numerous and much longer than cone cells, reaching to the pigment epithelial layer. In rods the inner and outer segments are of the same diameter whereas in cones, inner segments are much wider than the outer segments which taper distally. While the nuclei of rods are located at all levels within the outer nuclear layer, in the light-adapted condition at least, cone nuclei are predominantly located scleral to the external limiting membrane. The synaptic terminal of rods displays 2-3 invaginated (ribbon) synaptic sites while cones have 8-10 such sites. Both rods and cones also possess superficial synaptic sites. Apparent cellular degeneration is quite widespread amongst rods and is also occasionally noted for cone photoreceptors.     

Fine structure of the oocyst wall and excystation ofEimeria procyonis from the American raccoon (Procyon lotor)

Oocysts ofEimeria procyonis, from the American raccoon (Procyon lotor), were broken, added to a cell suspension, fixed in Karnovsky's fluid, and studied with the electron microscope. The oocyst wall has three layers: a thin electron-dense inner layer (8–15 nm), an electron-lucent middle layer (25–35 nm), and a thick outer layer (120–140 nm). The outer layer has an electron-dense inner portion and an electron-lucent outer portion that contains membrane-bound vesicles. When exposed to a trypsin-sodium taurocholate fluid, sporozoites excysted from most sporocysts which were 35–43 months old, but not from sporocysts that looked normal and were 106 months old. Excysted sporozoites measured 13–16×3–4 (mean 14.3×3.2) m, usually had two refractile bodies, and had a nucleus with a prominent nucleolus.     

Fine structure of the secretory and nonsecretory ameloblasts in the frog. I. Fine structure of the secretory ameloblasts

Amelogenesis in the tooth germs of the frog Rana pipiens was examined by electron microscopy at different stages of tooth development. Cellular changes in secretory ameloblasts during this process showed many basic similarities to those in mammalian amelogenesis. Amelogenesis can be divided into three stages based on histological criteria such as thickness of enamel and the relative position of the tooth germ within the continuous succession of teeth. These stages are early, transitional and late. The fine structure of the enamel-secreting cells reflects the functional role of these ameloblasts as primarily secretory in the early stage, possibly transporting in the late stage and reorganizing between the two functions in the transitional stage. In early amelogenesis the cell exhibits well-developed granular endoplasmic reticulum, Golgi complex, microtubules, dense granules, smooth and coated vesicles, lysosome-like bodies in supranuclear and distal portions of the cell and mitochondria initially concentrated in the basal part of the cell. Numerous autophagic vacuoles are observed concomitant with the loss of some cell organelles at the transitional stage. During late amelogenesis the ameloblasts exhibit numerous vesicles, granules, convoluted cell membranes, junctional complexes and widely distributed mitochondria. Toward the end of amelogenesis, cells become oriented parallel to the enamel surface and the number of organelles is reduced. Amelogenesis in the frog is an extracellular process and mineralization seems to occur simultaneously with matrix formation.     

Early events in the formation of a tissue structure from dispersed bovine adrenocortical cells following transplantation into scid mice

The early events that follow the transplantation of dispersed bovine adrenocortical cells into scid mice were investigated. We introduced adrenocortical cells into a small cylinder inserted beneath the kidney capsule, where they form a tissue structure that becomes vascularized and secretes steroids that replace those from the animal's own adrenal glands, which are removed during the transplantation surgery. We studied cell proliferation, cell survival, apoptosis, and the role of p21WAF1/CIP1/SDI1 over the first 6 days following transplantation. Additionally we examined the invasion of the tissue by host macrophages and endothelial cells. The data show that there is healthy survival of most of the transplanted cells, and that this is related to their position in the cell transplantation cylinder. In the layer of cells that was adjacent to the kidney parenchyma there was a higher rate of cell proliferation and a lower rate of apoptosis than in cells that were located in the upper part of the cylinder. In the lower layer cells were more likely to have nuclear p21, and macrophages and endothelial cells were observed only in this region. Cells that incorporated bromodeoxyuridine administered to animals 2 or 4 days following transplantation were not more likely than other cells to be undergoing a second division when the animals were killed at 6 days, suggesting that proliferation in the lower layer is not confined to a small subpopulation of cells. Among different animals, the extent to which the spaces between the transplanted cells became lined by host endothelial cells was correlated with higher levels of proliferation and nuclear p21, suggesting that vascularization is the critical step for the continued survival and proliferation of the transplant. The present experiments show that bovine adrenocortical cells transplanted into scid mice form a useful model for the study of tissue formation from dispersed cells and the interaction of the transplanted cells with the host.     

The central adaptation syndrome: Psychosocial stress as a trigger for adaptive modifications of brain structure and brain function

This review makes an attempt to combine data from biological and psychosocial stress literature and to suggest an alternative interpretation of the relationship between stress and disease. It rearranges the presently available knowledge on the short- and long-term effects of stress on many different aspects of brain structure and brain function in the form of a new conceptualization of the biological role of the stress response. The higher associative brain structures are not only the sites in which environmental and psychosocial demands are recognized and from which a less or more systemic, i.e. controllable or uncontrollable, stress response is initiated. They are also the sites which are primarily affected in the course of the stress response: the stress response acts as a trigger for the adaptive modification of the structure and the function of the brain of higher vertebrates and serves thus to adjust, in a self-optimizing manner, the behavior of an individual to the ever-changing requirements of its external world. This novel concept summarizes a large amount of information into a framework that lends itself to testable strategies for future research.     

Composition of the human zona pellucida and modifications following fertilization

The composition of individual human zonae pellucidae and modificationsto this extracellular coat both before and after fertilizationwere analysed using a rapid, sensitive, non-radioactive biotinylation-or lectin-based detection system; these assays use commerciallyavailable reagents and can be performed on fragments of individualzonae pellucidae. The zona pellucida from unfertilized eggsis composed of three glycoprotein species designated as huZP1,huZP2 and huZP3. Under non-reducing conditions, the molecularweights of these proteins are 150 kDa,100 kDa, and 55–65kDa respectively. Following fertilization, huZP1 was not detectedunder either non-reducing or reducing conditions. In contrast,after fertilization huZP2 was detected under non-reducing conditions,but not under reducing conditions. The ability to detect pre-and post-fertilization changes in a single human zona pellucidais discussed in relation to its value in assessing deficienciesin clinical and laboratory protocols used for in-vitro fertilization. fertilization/human/in-vitro fertilization/zona pellucida     

Retinal fine structure in the European eel Anguilla anguilla. VIII. Photoreceptors of the sexually mature silver eel stage

The morphology of the photoreceptors of the sexually mature silver eel has been investigated by electron microscopy and these findings compared with observations made on the photoreceptors of the glass, yellow and sexually immature silver eel stages of the lengthy life cycle of the European eel (Anguilla anguilla). As in previous stages the photoreceptors of the sexually mature silver eel are adequately described as either rods or single cones. The rod: cone ratio at this stage is about 200: 1 which is the highest ratio of any of the stages investigated. Rods and perhaps also cones are capable of photomechanical movements. In the light-adapted stage studied, rod inner segments are the same width in the ellipsoid region as the outer segments but the rod myoid region is much thinner. Rod outer segments in the mature silver eel are slightly longer than that observed in the immature silver eel but remain much the same diameter as in previous stages. Cone outer segments taper distally and are not as wide as the inner segments. Both rods and cones display organelles in the inner segment region indicative of active protein production as it is well established that the inner segment is the synthetic center of these cells. In most cones degenerative changes were noted in the mitochondria of the ellipsoid and in the presence empty vacuoles within their cytoplasm. Cone nuclei are large and vesicular and in the light-adapted state are always located sclerad to the external limiting membrane. Rod nuclei are smaller and more electron dense and located within the outer nuclear layer. Both rods and cones still show both invaginated (ribbon) and superficial synaptic sites. In the sexually mature silver eel, therefore, the rod: cone ratio becomes higher still; the rod outer segments become somewhat longer in length and cone cell degenerative changes are even more widespread.     

Fine structure of the monkey epididymis

The monkey epididymis was subdivided into four regions: initial segment (continous with the ductuli efferentes), head, body and tail. The initial segment possesses a very tall columnar epithelium (108 ± 4 μm). Epithelial height in the head, body and tail is diminished to 81 ± 5 μm, 69 ± 2 μm, and 50 ± 5 μm, respectively. The pseudostratified epithelium is composed of four main cell types: principal, apical and basal epithelial cells, and intraepithelial lymphocytes. Occasional macrophages are also found in the epithelium. The tall, narrow, columnar principal cells demonstrate morphological features characteristic of absorption and secretion. An unusual feature, apparently unique to the primate, is the presence of deep invaginations of the apical cytoplasm which contain membrane-bounded vacuoles. Similar, but larger vacuoles are present among the stereocilia and in the tubular lumen. Large clusters of mitochondria and electron-dense membrane-bounded granules characterize the infranuclear region of the cytoplasm. Principal cells are studded with closely aligned stereocilia. Their nuclei are spindle-shaped in the initial segment and first portion of the head region, but become highly infolded in the distal head, body and tail portions. The apical or mitochondrion-rich cells possess a cytoplasm which extends from the base of the epithelium to the tubular lumen. Basal cells contain few organelles and are found throughout the length of the duct. Arterioles and capillaries appear to penetrate directly into the epithelium from the underlying connective tissue; however, the basal lamina of the epididymal duct always intervenes between the endothelium of the blood vessels and the epithelial cells. Several of the above observations have not been noted in rodents and other mammalian species and may be unique to the primate.     

Retinal fine structure in the European eel Anguilla anguilla. VI. Photoreceptors of the sexually immature silver eel stage

This report deals with the fine structure of the photoreceptors of the sexually immature silver eel and compares these findings with previous observations on the glass and yellow eel stages of the life cycle of the European eel. The photoreceptors of the sexually immature glass eel are readily categorized as either rods or cones. No multiple cones are observed. The rod:cone ratio is about 100:1, which is greater than that of either the glass or yellow eel stages. Rods and perhaps cones also are capable of retinomotor responses. In the light-adapted condition, rod inner segments are the same width as the outer segments but narrow abruptly below the ellipsoid to form the myoid. Rod outer segments in the immature glass eel are longer but much the same diameter as that noted for the glass and yellow eel. Cone inner segments are much wider than the outer segments which taper distally. Both rods and cones display organelles in the inner segment region indicative of protein production. Most of the cones observed at this stage showed some degenerative signs mostly as empty vacuoles within their cytoplasm. Cone nuclei are large and vesicular and in the light-adapted state are invariably located sclerad to the external limiting membrane while rod nuclei are small and dense and located vitread to this membrane. Both rods and cones display both invaginated and superficial synaptic sites. The most obvious changes noted in the immature silver eel photoreceptor population are a marked rise in the rod:cone ratio and a lengthening of rod outer segments.