bluuebunny/crossref_metadata_2025 huggingface dataset:
Light and electron microscopic observations on hydrocortisone‐induced cleft palate in hamsters
Authors: Shah Ravindra M. , Travill Anthony A.
Published: February 2005

Palatal histogenesis in hydrocortisone‐treated hamster fetuses was studied by both light and electron microscopy. At an early stage in the hydrocortisone‐affected fetuses, when the palatal shelves hung vertically on either side of the tongue, necrotic changes could be seen in some of the basal epithelial cells which lay adjacent to the fragmented basal lamina. The normal looking cells lay on an intact basal lamina and were attached to the contiguous necrotic cells by desmosomes. With horizontal reorientation of the palatal shelves and their approach to the midline, cellular necrosis and fragmentation of the basal lamina increased. When compared with normal cells, the hydrocortisone‐affected ones were seen to be lighter, to contain fewer ribosomes and no lysosomes. At a later stage, when midline palatal fusion was lacking, the epithelium underwent stratification and keratinization while the necrotic debris was removed by mesenchymal macrophages. It appears that the normal process of protein synthesis is inhibited following hydrocortisone administration and that this, in turn, during palatogenesis, disrupts normal cellular differentiation and the integrity of the basal lamina, which are associated with the production of a cleft palate.
Movement of entire cell populations during renewal of the rat incisor as shown by radioautography after labeling with 3H‐thymidine. The concept of a continuously differentiating cross‐sectional segment
Authors: Smith C. E. , Warshawsky H.
Published: February 2005

Renewal of the rat incisor was studied in three dimensions by employing a serial cross‐sectioning technique to locate the boundary between labeled and unlabeled cells in the enamel organ and odontoblast layer at various times after a single injection of 3H‐thymidine. This boundary, or leading edge of the front of labeling, was graphically illustrated through point‐plotting reconstruction of the labial surface of the incisor. At one hour after the injection of 3H‐thymidine the front of labeled ameloblasts was located within the presecretory zone related to early predentin secretion. This front formed a “C”‐shaped curve stretching across the labial surface of the tooth from the lateral to the mesial cemento‐enamel junction. The “C” was open anteriorly and the lateral arm extended almost twice as far incisally as the mesial arm. The edge of the front of labeled odontoblasts was positioned apical to and parallel with this “C”‐shaped curve. The morphological appearance of all cells along each respective front was found to be similar. As the fronts of labeled ameloblasts and labeled odontoblasts moved forward with the erupting incisor, the cells along these fronts differentiated simulataneously and subsequently formed enamel and dentin. Throughout this movement the distance between fixed points along the leading edge of the front of labeled ameloblasts, and its positional relationship to the front of labeled odontoblasts, did not change appreciably. This indicated that cells of the tooth were being carried incisally at a uniform speed. It was concluded that renewal in the rat incisor consists of the generation by the bulbous part of the odontogenic organ of epithelial “U”‐shaped cross‐sectional segments which enclose a core of pulp. As this segment is transported towards the gingival margin, cellular differentiation and subsequent formation of hard tissue is seen to begin at the central labial side of the segment and to progress in a mesial and lateral direction towards the lingual side. In the process, the limits of the enamel organ at the mesial and lateral cemento‐enamel junctions are established and the entire circumference of the segment is eventually enclosed by a rim of dentin.
Mitochorial form in hepatic parenchymal cells in rats of several ages
Authors: Stempak Jerome , Laurencin Mary
Published: February 2005

Slices of livers from neonatal, 7‐day‐old and adult rats were fixed in osmium tetroxide or a formaldehyde‐osmium tetroxide sequence and processed for electron microscopy. Mitochondria from neonatal hepatic parenchymal cells are pleomorphic. Disc‐shaped forms are common. In 7‐day‐old animals, cylinders are the most numerous single from, discs are present but smaller, and spherical forms increase in number. In the adult, mitochondria are predominantly cylindrical in from. The average volume of neonatal mitochondria is greater than that of 7‐day‐old or adult mitochondria.
Architecture of the marrow vasculature in three amphibian species and its significance in hematopoietic development
Authors: Tanaka Yasukazu
Published: February 2005

Architecture of the bone marrow vasculature, particularly that of the femur, was analyzed in three amphibian species in relation to the early phylogeny of marrow hematopoiesis. A dye‐injection method and histological techniques, including both serial sectioning and reconstruction methods, were used for this purpose. From these observations the following conclusions may be drawn. (1) Marrow hematopoiesis is absent from the femur of the urodelan (Triturus pyrrhogaster) and appears first in the femur of the primitive anuran (Xenopus laevis). (2) The site of primitive hematopoiesis (granulopoiesis) is the subendosteal region where the venous vascular net develops. (3) The primitive vascular architecture observed in the femur of Xenopus is characterized by the absence of a central vein. Subendosteal veins drain the blood from the bone marrow. A vein collateral to the primary artery appears in the femur of Rana catesbeiana, an advanced anuran, in which further development of both the subendosteal venous plexus and hematopoietic activity are noted. In both anura examined, the primitive blood sinuses form near the mid‐shaft of the femur. The proliferation of mesenchymal elements containing dark pigment, presumably melanin, was also noted in this area. (4) The architecture of marrow vessels in Rana approaches the structure noted in mammalian bone marrow. (5) Fat tissue is observed in the urodelan bone marrow prior to the appearance of hematopoietic activity. This indicates that the formation of marrow fat is phylogenetically unrelated to the development of hematopoiesis.

The present investigation on primitive hematopoiesis suggests that the development of hematopoietic activity is intimately related to the development of the marrow vasculature, particularly that of the subendosteal venous plexus. A favorable vascular arrangement may be necessary to allow active hematopoiesis.
Ultrastructure of the thyroid in dwarf mice
Authors: Cordier André C. , Denef Jean‐François , Haumont Stanislas M.
Published: February 2005

The thyroid gland of Snell's dwarf mice consists of small follicles with flattened epithelium, partly differentiated cords and undifferentiated masses. Many adipocytes are found. The ultimobranchial cysts are well developed. Parafollicular cells are normal. In the partly organized cords, microfollicular cells and some small follicles limited by two or three cells are seen.

The presence of these structures led us to think that they represent the first stages of normal folliculogenesis, described as the fusion of two adjacent unicellular microfollicles. Their further growth is the result of the coalescing of small adjacent follicles or of cellular multiplication. The presence of undifferentiated masses and partly differentiated cords, in dwarf mice, seems due to a developmental arrest rather than to aberrant development. This disorder of organogenesis is ascribed mainly to a lack of pituitary growth hormone.
Immunohistochemical localization of somatostatin, insulin and glucagon in the principal islets of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctata)
Authors: Johnson Dana E. , Torrence Judith L. , Elde Robert P. , Bauer G. Eric , Noe Bryan D. , Fletcher Donald J.
Published: February 2005

Somatostatin, insulin and glucagon were localized in the principal islets of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctata) by means of the unlabeled antibody‐peroxidase‐antiperoxidase immunocytochemical method. Both species showed a similar ratio of positive cells 9:6:4 (insulin:somatostatin:glucagon), but the interrelations of the three cell types differed between species. The large number of somatostatin‐positive cells may be indicative of an important role for this hormone in teleost physiology. The principal islets appear to be a good source of tissue for further work on somatostatin.
Glucagon levels in pancreatic extracts and plasma of the lizard
Authors: Rhoten William B.
Published: February 2005

Levels of glucagon in the splenic pancreas and in plasma of the lizard Anolis carolinesis were estimated by radioimmunoassay. The splenic pancreas of Anolis has a glucagon concentration nearly a 1000 times greater, on a weight basis, than that of the mammalian pancreas. Glucagon‐like immunoreactivity (GLI) of anolian plasma varied over a wide range, but relative to mammals the GLI levels were inappropriately elevated for the concentration of plasma glucose. The anole may prove valuable in studies on the regulation of glucagon secretion, particularly as related to alpha cell function in the diabetic state.
Light and electron microscopic localization of acetylcholinesterase activity in the rat renal nerves
Authors: Barajas Luciano , Wang Patricia , De Santis Steve
Published: February 2005

Acetylcholinesterase activity is shown in the renal nerves of the rat with the technique of Karnovsky and Roots. By light microscopy, the acetylcholinesterase‐positive nerves are seen in association with blood vessels, including the glomerular arterioles, and occasionally with renal tubules. By electron microscopy the precipitate appears extracellularly around axons and varicosities. DFP inhibits the deposition of precipitate. Previous demonstration by serial section electron microscopy in the rat revealed that all nerves around the glomerular arterioles contain small dense‐cored vesicles characteristic of adrenergic nerves, indicating that the acetylcholinesterase‐positive nerves demonstrated here are likely to be adrenergic nerves containing acetylcholinesterase.
Endothelial DNA synthesis in the microvasculature of rat skin during the hair growth cycle
Authors: Sholley Milton M. , Cotran Ramzi S.
Published: February 2005

Earlier studies of the vascular patterns around hair follicles revealed that actively growing follicles have an extensive microvasculature relative to that around quiescent follicles. In order to determine whether the establishment of the active perifollicular vascular pattern involves replication of endothelial and perivascular cells, we studied the 3H‐thymidine labeling indices of these cells in autoradiographs of rat skin from regions containing either actively growing follicles or recently inactive follicles. In skin containing inactive follicles, the endothelial labeling index was 0.22%, a figure similar to those reported for the endothelium of small blood vessels in several other non‐stimulated adult tissues. However, skin containing actively growing follicles displayed an endothelial labeling index of 2.35%. The labeling indices of perivascular cells paralleled those of the endothelial cells. Thus, endothelial and perivascular cells in vessels associated with actively growing follicles undergo significantly more DNA synthesis than those in vessels associated with inactive follicles. Replication of these cells apparently contributes to the extension of the microvascular network around growing follicles.
The binding of calcium within the Golgi saccules of the rat odontoblast
Authors: Reith Edward J.
Published: February 2005

Odontoblasts of developing rat molar teeth were treated with OsO4‐pyroantimonate to ascertain the localization of calcium. In addition, some tooth germs were incubated in solutions which were intended to allow for the escape of diffusible ions prior to fixation in OsO4‐pyroantimonate. In tissues treated directly with OsO4‐pyroantimonate, antimonate reaction product was found chiefly in abacus bodies and secretory granules of the Golgi region and in secretory granules in the distal pole of the cell. Lesser amounts of reaction product were found in the extracellular space, mitochondria, nucleus and generally throughout the cell. Tissues pre‐treated to allow for the escape of diffusible ions showed reaction product, identified as containing calcium, only in the abacus bodies and secretory granules.

These results are considered to reflect the binding of calcium within the Golgi apparatus of the odontoblast. Moreover, since it has been shown by others that the abacus bodies and secretory granules contain collagen precursor, it is suggested that the collagen precursor is being seeded with calcium within the Golgi apparatus and that this intracellular calcium binding will play a role in facilitating the major wave of extracellular mineralization of the dentin which is to follow.
Stability of the intra‐epithelial component of the blood‐testis barrier in epinephrine‐induced testicular degeneration in Syrian hamsters
Authors: Gravis C. J. , Chen I. , Yates R. D.
Published: February 2005

Adult male Syrian hamsters were given daily intraperitoneal injections of epinephrine (1.0 mg/kg) and papaverine, a vasodilator, (60 mg/kg) for a period of ten days. After the treatment period, lanthanum and horseradish peroxidase tracer studies were used to examine the intra‐epithelial component of the blood‐testis barrier. Degenerating tubules often exhibited only Sertoli cells and spermatogonia, or Sertoli cells alone. Sertoli cell processes in the degenerating tubules often arched out from the main cell body to make contact with other Sertoli cell processes, forming a series of vacuole‐like spaces in the germinal epithelium, adluminal to the Sertoli‐Sertoli junctions. At the site of contact between these arching Sertoli cell processes one to eight tight junctions had formed, with hexagonal arrays of Sertoli cell cytoplasmic filaments located immediately adjacent to these junctions. Cisternae of the Sertoli cell endoplasmic reticulum lay deep to the layer of cytoplasmic filaments. It appeared that these junctions had originated after the expulsion of the germinal elements of the seminiferous epithelium. Penetration of the tracers in the degenerating seminiferous tubules was prevented by what appeared to be normal Sertoli‐Sertoli junctions located between apposed Sertoli cells, adluminal to the remaining spermatogonia when these resisted degeneration, or just adluminal to the basal lamina in those tubules in which spermatogonia were absent.
Absorption from the peritoneal cavity: Sem study of the mesothelium covering the peritoneal surface of the muscular portion of the diaphragm
Authors: Tsilibary Effy C. , Wissig Steven L.
Published: February 2005

Colored tracers, injected intraperitoneally in mice, are taken up by diaphragmatic lymphatics, outlining their large, terminal cisterns, the so‐called lacunae. The lacunae occur exclusively on the muscular portion of the diaphragm. The mesothelium covering non‐lacunar and lacunar areas of the muscular portion was examined with the SEM. Mesothelial cells overlying non‐lacunar areas are extremely flat, and their boundaries are indistinct. Mesothelial cells overlying lacunae protrude towards the lumen of the peritoneal cavity and have distinct outlines. There are openings or stomata, 4‐12 μm in diameter, between them. Some of the stomata overlie a deep pit; others overlie a shallower pit in which the surface of another cell can be seen beneath the opening. It seems likely that the bulk of the fluid draining from the peritoneal cavity passes through these stomata into underlying lymphatic lacunae.
Ultrastructural identification of the Sertoli cell in the testis of the northern pike, Esox lucius
Authors: Grier H. J. , Linton J. R.
Published: February 2005

Identification of the intralobular Sertoli cell in the testis of Esox lucius is based upon residual body phagocytosis. Formerly, this lipid‐containing cell type was referred to as the “lobule boundary cell” and erroneously believed to be homologous to the interstitial Leydig cell.
Morphology of the intrarenal lymphatic system. Capsular and hilar communications
Authors: Holmes Michael J. , O'Morchoe Patricia J. , O'Morchoe Charles C. C.
Published: February 2005

Recent functional evidence has indicated that ureteric obstruction for three or more days in dogs causes a diversion of renal lymph from the hilar to the capsular system. The present study was concerned with the structural correlate of this functional evidence, having special reference to communications between the two systems. Within three days of ureteric occlusion the capsular lymphatic system became dilated. On histological examination two types of tributaries were found. One (termed a perforating lymphatic) served as a primary pathway for superficial cortical lymph from the subcapsular plexus, and penetrated the capsule either alone or in company with a small vein. The other (termed a communicating lymphatic) was closely associated with the occasional penerating interlobular blood vessel which traversed the capsule to ramify in the perirenal tissue. Approximately 60% of the penetrating arteries in eight dog kidneys had associated communicating lymphatics. On the renal surface the perforating and communicating lymphatics formed the primary collecting vessels of the capsular system. Within the renal substance the communicating lymphatics were directly continuous with lymphatics which surrounded the interlobular blood vessels and which have been shown to drain into the hilar network. Thus the communicating lymphatics formed direct connections between the hilar and capsular systems. It was concluded that these communications, although dilated by hydronephrosis, existed under control conditions. Functionally they are probably of importance only under special circumstances when intrarenal lymph may be diverted from one to the other system.
The fine structure of blood vessels of the telencephalic germinal matrix in the human fetus
Authors: Povlishock John T. , Martinez A. Julio , Moossy John
Published: February 2005

Blood vessels of the human telencephalic germinal matrix during the tenth through the twenty‐second week of gestation have been examined by light and electron microscopy. In all fetuses studied the ependymal and sub‐ependymal zones of the germinal matrix have a prominent vascular network. During the tenth and twelfth weeks of gestation, the endothelial cells are plump and display numerous organelles, junctional complexes, conspicuous luminal microvilli and stub‐like abluminal projections. Coated and micropinocytotic vesicles were found both in the cytoplasm and on luminal and abluminal surfaces. In endothelial cells intracytoplasmic, membrane‐limited, rod‐shaped bodies were frequently observed. These bodies have been linked to endothelial thromboplastic and clotting activities and related to abnormal clotting status. Their role in the pathogenesis of subependymal germinal matrix hemorrhage in premature infants remains unknown. Pericytes apposing the endothelial cells were recognized in all gestational periods. The endothelial basal lamina and astrocytic end‐feet are ill defined, and the extracellular space is pronounced. By the fifteenth and seventeenth weeks of gestation the endothelial cells are still large and now possess more numerous luminal microvilli and abluminal projections. At this stage the pericytes, basal lamina and astrocytic end‐feet are all well developed, resulting in a decrease in the surrounding extracellular space. By the twenty‐second week the endothelial cells possess few luminal and abluminal projections and the associated basal lamina, glia, pericytes and extracellular compartment appear mature. The relationship of the germinal matrix vasculature to the pathogenesis of subependymal hemorrhage is discussed.
Fine structure of the monkey epididymis
Authors: Ramos Angel S. , Dym Martin
Published: February 2005

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.
Effects of clomiphene on the structure of the testis, epididymis and sex accessory glands of the rat
Authors: Flickinger Charles J.
Published: February 2005

Young adult male rats were treated with clomiphene citrate, a non‐steroidal inhibitor of gonadotropin release in the rat. They were administered 2.5, 3.5, or 5.0 mg/100g/day for intervals up to 12 weeks. The weights of the sex accessory glands were less than those of control rats, and decreased with increasing dose and length of treatment. At the longer intervals, the weights of the testis and epididymis were also less than those of control animals. Microscopic alterations in the testis included a scarcity or even absence of late spermatids, the presence of necrotic cap‐phase spermatids, and accumulation of lipid droplets and large lysosome‐like structures in Sertoli cells. In rats treated for the longest interval, 12 weeks, testicular changes were even more extensive; degenerating primary spermatocytes were observed, and in one rat germ cells were virtually completely absent and the seminiferous tubules were occupied by Sertoli cells. The Leydig cells of treated animals were smaller than those of normal or control rats. Sperm were absent from the lumen of the caput epididymidis in most specimens. Although the epithelium of the caput appeared reduced in height in some samples, ultrastructural changes in cellular organelles were not detected. In most specimens of the cauda epididymidis, the lumen was small, irregularly shaped, and lacking in sperm. Light cells were prominent in the epithelium by virtue of their content of many apical vacuoles and dense granules. In some specimens of the distal cauda epididymidis, the duct had a circular profile and the lumen contained round cells and debris. The seminal vesicle and the ventral prostate were greatly suppressed. The normally tall columnar epithelia were reduced to a low columnar or cuboidal shape. Especially at the longer treatment intervals, the normally abundant rough endoplasmic reticulum was sparse, and in some samples secretory vacuoles were absent. The possible mechanism of production of these morphological changes is discussed, and the results are compared with those following treatment with other antifertility agents, including cyproterone acetate, a progestin, and a progestin‐androgen regimen.
Scanning electron microscopy of the developing alimentary canal in the chick
Authors: Lim Soo‐Siang , Low Frank N.
Published: February 2005

Fresh pullet eggs (White Leghorn strain) were incubated from 11 to 21 days. Embryos were killed by decapitation and portions of the esophagus, crop, proventriculus, gizzard, small intestine, caecum and rectum were dissected and removed rapidly. The inner lining of the gut was exposed by using small needles to pin the cut edges of the tube to a wax plate immersed in Hank's fixative modified with aldehydes (Litke and Low, ′77). Preparation for scanning electron microscopy (SEM) was routine.

Esophageal cilia appeared in tufts along with microvilli and microplicae. These were more frequent at the lower end of the esophagus. Developing cilia were present. In the 12‐day proventriculus, structures resembling macrovilli were predominant. These disappeared by the seventeenth day, when aggregates of rounded cells covered with microvilli appeared. The gizzard acquired a prominent rounded cellular appearance with microvilli at 17 days. These cells increasingly elongated and flattened out towards hatching (21 days). Observations of the duodenum confirmed those made by Grey (′72). A hexagonal pattern of cells was also observed. The ridges of the ileal portion of the small intestine were larger and fuller than in the duodenum. Formation of rectal villi was not as well organized as in the small intestine. Villi could be seen scattered at random at 12 days. By 17 days, definitive ridges were seen. The villi in the cloacal region of the rectal area were extremely long and elaborate, as previously reported by Zeitschmann (′02, cited by Calhoun, ′57). Our observations show that the mucosal surfaces become highly specialized in different parts of the tract during development. Marked changes in geometric form occur during development.
Dictyosome‐like structures with cylindrical intersaccular connections (microtubules?) in guinea pig spermatocytes
Authors: Mollenhauer Hilton H. , Morré D. James
Published: February 2005

Structures superficially resembling dictyosomes were present in guinea pig primary spermatocytes and in spermatids in late stages of development. The dictyosome‐like structures (DLS) were composed of 2 to 17 saccules. Each saccule averaged about 20 nm in thickness (membranes plus lumen) and 400 nm in diameter and was separated from adjacent saccules in a stack by an intersaccular space of about 12 nm. Single saccules separated from the DLS were also present. Tubules up to 60 nm in diameter were continuous with the edges of the saccules and sometimes extended for several micrometers into the cytoplasm. The membranes of the tubules appeared similar to the saccule membranes. Some DLS saccules and tubules had coated vesicles attached to them.

A distinguishing feature of DLS was the presence of microtubule‐like structures, about 10 nm in diameter, that bridged the inter‐saccular spaces. Some of these bridging structures appeared continuous through one or more saccules. The bridging structures were often arranged in linear arrays or in clusters of three to four.

The membranes of the DLS appeared tripartite but stained differently from the membranes of the endoplasmic reticulum or Golgi apparatus. The inner (luminal) leaflet of the tripartite membrane usually appeared discontinuous or globular after fixation in glutaraldehyde‐osmium tetroxide. The DLS could be distinguished from all other cellular components and may represent a new organelle unique to spermatogenesis.
Morphology of the ependymal lining of the rabbit third ventricle following intraventricular administration of synthetic luteinizing hormone‐releasing hormone (LH‐RH): A scanning electron microscopic investigation
Authors: Bruni J. E. , Montemurro D. G. , Clattenburg R. E.
Published: February 2005

The morphology of the ependymal surface of the rabbit third ventricle was studied following intraventricular injections of an ovulatory dose of synthetic LH‐RH. Identically treated rabbits that received injections of saline, only, served as controls. Animals from both groups were killed 5 minutes and 15 minutes after the injections. The ependyma of the dorsolateral ventricular wall and transitional zone maintained a constant appearance from animal to animal regardless of treatment or time of autopsy. The uniformly non‐ciliated ependyma of the ventrolateral wall and floor (infundibular and mammillary recesses) of the ventricle, however, not only exhibited an appearance quite distinct from either the dorsolateral wall or transitional zone, but also exhibited a transient responsiveness to LH‐RH treatment. In the controls, most ependymal cells of this region bulged conspicuously into the ventricle. Numerous pleomorphic knob‐ of bleb‐like protrusions and occasional microvilli characterized their apical membranes. In contrast, marked changes were seen in the character of the ependymal surface of animals killed five minutes following LH‐RH administration. These changes, which principally took the form of numerous irregular microvillous eruptions of the apical membrane, pervaded the rostrocaudal extent of the infundibular and mammillary recesses. Equivalent regions of the ependymal surface in animals killed 15 minutes after LH‐RH administration, however, were similar to those of the controls. These transient morphological changes observed in the ependymal surface of the ventrolateral wall and floor of the ventricle five minutes after LH‐RH injection may reflect structural modifications associated with absorption of the hormone across the ependymal‐CSF interface.
Morphology of the pineal complex in seven species of lanternfishes (Pisces: Myctophidae)
Authors: McNulty John A. , Nafpaktitis Basil G.
Published: February 2005

The morphology of the pineal complex was compared in seven species of lanternfishes (family Myctophidae) using both light and electron microscopes. On the basis of compactness of the pineal end‐vesicle and presence or absence of a dorsal sac, the species in this study were divided into two groups. This grouping seems to correlate well with current views on the phylogenetic relationships among these fishes. Receptor cells and supportive cells are described in the pineals of all species examined. The deepest‐dwelling of the forms studied, Parvilux ingens, showed a significant increase in the mean number of lamellar membranes in the outer segments of the receptor cells and a higher convergence ratio of receptor cells to ganglion cells as compared to the shallow‐dwelling form Tarletonbeania crenularis. Accordingly it is suggested that the pineal of P. ingens is more photosensitive. Additional differences among species were found in the ultrastructure of the supportive cells. Dorsal sacs were absent in the three shallowest‐occurring myctophids studied. In those species with a dorsal sac, its close association with the pineal‐end‐vesicle suggests a functional relationship between the two structures.
The effects of various hormones on the surface morphology of testicular cells in culture
Authors: Hutson James C.
Published: February 2005

The purpose of this investigation was to study the effects of various hormones on the surface morphology of 20‐day‐old rat testicular cells in culture. Aggregates containing primarily Sertoli cells and germinal cells were obtained by enzymatic digestion. The surface morphology of the cells composing these aggregates was characterized under various culture conditions using light microscopy and scanning electron microscopy. The cytoplasmic processes of Sertoli cells became highly branched and filamentous after being cultured in the presence of rat, human or ovine FSH. Identical branching and filamentation was observed when Sertoli cells were cultured in rat TSH. Finally, numerous large blebs were observed on the surfaces of germinal cells cultured in the presence of insulin.

These results suggest that the branching and filamentation of Sertoli cell cytoplasm observed after FSH stimulation are not specific for that hormone.
Sites of steroid synthesis in the ovary of the cyclic hamster: A histochemical study
Authors: Saidapur Srinivas K. , Greenwald Gilbert S.
Published: February 2005

The histochemistry of lipids, Δ5‐3β‐, 20α and 17β‐hydroxy‐steroid dehydrogenases, glucose‐6‐phosphate and isocitrate dehydrogenases, NADH and NADPH‐diaphorases and acid phosphatase has been studied in the ovary of the cyclic hamster. None of the enzymes studied was present in the preantral follicles on day 1 (day of ovulation) or any day of the 4‐day cycle. With the development of antral follicles (on day 3) a few fine lipid droplets appeared in the granulosa cells. The theca interna exhibited moderate amounts of NADH‐diaphorase, Δ5‐3β‐HSDH, 17β‐HSDH and slight NADPH‐diaphorase, G‐6‐PDH and ICDH, whereas the granulosa cells of antral follicles showed weak Δ5‐3β‐HSDH, NADH‐diaphorase and moderate 17β‐HSDH but intense NADPH‐diaphorase, G‐6‐PDH and ICDH activities. All enzyme activities in both theca and granulosa became more pronounced on proestrus (day 4).

In the corpora lutea (CL) all the above enzymes were present on day 1 and increased on day 2, followed by a rapid decline on days 3 and 4. Lipids were sparsely represented in CL on days 1 and 2 but showed marked accumulations on days 3 and 4. Likewise, acid phosphatase increased on days 3 and 4. The enzyme 20α‐HSDH was not detectable in the CL.

The interstitium showed moderate amounts of lipids, Δ5‐3β‐HSDH and NADH‐diaphorase while 17β‐HSDH, NADPH‐diaphorase, G‐6‐PDH and ICDH were only weakly present. There were no appreciable changes in the lipid and various enzymes in the interstitium throughout the cycle except for Δ5‐3β‐HSDH which increased slightly on the afternoon of day 4. Acid phosphatase was not detected in appreciable amounts in the interstitium throughout the cycle.

These findings suggest that preantral follicles are unlikely to contribute to steroidogenesis. The antral follicles are the principal source of estrogen, with the granulosa being the major site of synthesis. The interstitium can serve as a major source of progesterone (P) while the theca interna and granulosa cells of antral follicles may form additional sites for P synthesis on the afternoon of day 4. The CL in the hamster are very short‐lived and steroidogenesis in them may proceed beyond the synthesis of progesterone. The present findings are correlated with the steroid levels found during the cycle. Appropriate comparisons are also made with the rat ovary.
Early postnatal development of ependyma in the third ventricle of male and female rats
Authors: Walsh Raymond J. , Brawer James R. , Lin Peck Sun
Published: February 2005

Ependyma in the third ventricle of developing male and female rats (0, 5, and 10 days postpartum) were compared with those of sexually mature male rats by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). No sexual dimorphism appeared in the developmental group. At all ages the dorsolateral ventricular wall was composed of ciliated ependymal cells, while ependymal cells of the ventrolateral wall exhibited apical microvilli and bleb‐like irregularities.

While SEM revealed similarities in apical morphology between ependymal cells of adult and developing animals, TEM revealed marked differences between these cells. Many ciliated ependymal cells in developing animals resembled those of the adult while other neonatal cell profiles suggested ciliogenesis.

Adult male rats exhibited two distinct tanycyte populations. One population, characterized by elaborate intercellular interdigitations and basal processes containing predominantly fine filaments, occurred adjacent to the ventromedial nucleus (VMN). The second population, characterized by less extensive intercellular interdigitations and basal processes containing, primarily microtubules, lined the roof of the lateral recess adjacent to the arcuate nucleus. Many tanycytes at the level of the arcuate nucleus in developing rats resembled closely those of the adult. In contrast, developing ependymal cells at the level of the VMN differed from their adult counterparts in that they exhibited little intercellular interdigitation and projected basal processes characterized by an internal framework of microtubules.

Similarities in cytology between developing and adult tanycytes of the arcuate region suggest that the adult function of this population may be operative in the early postnatal period. In contrast, the differing cytology between adult and developing tanycytes of the VMN region suggests that the function of these cells is age‐dependent.
Sexual differences among duodenal glands of hamster
Authors: Shackleford John M. , Wilborn Walter H.
Published: February 2005

This histochemical study was undertaken to determine whether sexual differences existed in the duodenal glands of hamster. Alcian blue staining and atomic absorption spectrophotometry (for copper content of the bound Alcian blue) showed the duodenal glands of males to contain about double the acid mucosubstance of the female glands. Periodic acid Schiff staining was stronger in the females over a larger portion of the gland than in males. It was concluded that sexual differences were evident in duodenal glands of hamster.
Projections from the parvocellular vasopressin‐ and neurophysin‐containing neurons of the suprachiasmatic nucleus
Authors: Sofroniew Michael V. , Weindl Adolf
Published: February 2005

The efferent projections of the parvocellular vasopressin‐ and neurophysin‐containing neurons of the suprachiasmatic nucleus (SCN) have been investigated in the mouse, rat and guinea pig, using specific antisera to vasopressin and neurophysin in the unlabelled antibody‐enzyme immunoperoxidase method. In all three species, parvocellular perikarya containing vasopressin and neurophysin were found in the SCN, primarily in the medial, dorsal and rostral part of the nucleus. The fine‐caliber vasopressin‐ and neurophysin‐containing fibers arising from SCN neurons can easily be distinguished from the large‐caliber vasopressin and neurophysin fibers of magnocellular neurons which pass from the supraoptic and paraventricular nuclei primarily to the neural lobe of the pituitary, but also to extrahypothalamic sites. Fine‐caliber fibers leave the SCN in various directions to form several pathways. The major projections run (1) rostrodorsally to the lateral septum, and (2) dorsally to the medial dorsal thalamus and lateral habenula. Smaller projections course rostrally to the nucleus of the diagonal tract (of Broca), and dorsocaudally to the posterior hypothalamus and interpeduncular nucleus. In addition, many fibers of the dorsal thalamic projection continue beyond the lateral habenulae through the central grey of the mesencephalon to the area of the nucleus of the solitary tract. In all target areas, fibers were observed only in distinct portions of the nuclei and were not distributed to the whole nucleus. None of the fine‐caliber fibers from SCN neurons project to, or even towards, the median eminence and neural lobe. No oxytocin‐positive SCN neurons or fine‐caliber fibers could be found. In Brattleboro rats, with hereditary vasopressin deficiency, no vasopressin‐ or neurophysin‐positive SCN neurons or fine‐caliber fibers could be found. In contrast to vasopressin and neurophysin fibers from magnocellular neurons of the supraoptic and paraventricular nuclei, fine‐caliber vasopressin and neurophysin fibers from SCN neurons do not terminate at capillaries. A large number of these fibers make axo‐somatic contacts with neurons in the projection areas. It is concluded that vasopressin and neurophysin from parvocellular SCN neurons are not released into the bloodstream, but may affect neurons in the projection areas described.
Selective binding of antibody against gizzard 10‐nm filaments to different cell types in myogenic cultures
Authors: Fellini S. A. , Bennett G. S. , Holtzer H.
Published: February 2005

Antibody against the intermediate‐sized filaments from gizzard smooth muscle was used to determine the presence or absence of reacting 10‐nm filaments in different cell types. The antibody against gizzard 10‐nm filaments reacted with filaments in cultured smooth muscle cells, skeletal myotubes and postmitotic skeletal myoblasts. It did not bind to the 10‐nm filaments present in replicating presumptive myoblasts and fibroblasts, or the 10‐nm filaments in spinal ganglion cells.
Sites of cerebrovascular injury induced by radiographic contrast media
Authors: Casady Robert L. , Kitten Gregory T. , Bradley Irene M. , Sterrett Patrick R.
Published: February 2005

The object of this study was to determine the type of cerebral vessel affected by injection of radiopaque contrast agents used in cerebral angiography. Seventeen rabbits were prepared surgically for a left intracarotid injection of methylglucamine iothalamate (Conray 60) or methylglucamine diatrizoate (Reno‐M‐60). Extravasations of the tracers, Evans blue and horseradish peroxidase, occurred in the left half of the brain and occasionally in the right half. Within those areas of blood‐brain barrier breakdown, the frequency of leakage was 60% for arterioles, 25% for venules, and 12% for capillaries. The leakage appeared to be primarily intercellular, rather than intracellular. This study provides evidence that greater blood‐brain barrier alterations occur in arterioles and venules than in capillaries following cerebral angiography.
Development of cell types and of regional differences in the postnatal rat epididymis
Authors: Sun Eric L. , Flickinger Charles J.
Published: February 2005

The development of cell types and regional differences in the rat epididymis was studied in specimens of the initial, middle and terminal segments prepared at intervals between birth and postnatal day 94. The development of the epididymis was divided into three phases: (1) an undifferentiated period; (2) a period of differentiation, and (3) a phase of expansion. During the undifferentiated period, from birth to day 15, the epithelial cells had a uniform appearance. Halo cells, which are believed to be migratory leukocytes, appeared on day 14. The period of differentiation extended from day 16 to day 44. Slender, densely staining cells, termed narrow cells, appeared in the epithelium of all three segments on day 16, constituting the first evidence of differentiation of cell types in the epididymal epithelium per se. In addition to their shape and apical nuclei, the narrow cells were distinguished from other epithelial cells by the presence of cup‐shaped apical vacuoles and mitochondria with tubular cristae. Principal cells and basal cells were identified on day 28, which also marked the first distinction of differences in epithelial height among the different segments. Narrow cells persisted into the adult in the initial segment. In the middle and terminal segments, however, narrow cells disappeared by day 35, when light cells made their appearance. The major event of the period of expansion, from day 45 to 3 months, was the appearance of sperm in the lumen between days 45 and 52. A model for differentiation of cell types in the epididymis is proposed and it is suggested that narrow cells are precursors to light cells in the middle and terminal segments. The development of ultrastructural features of adult cell types preceded the appearance of sperm in the lumen.
A transmission and scanning electron microscopic study of the saccule in five species of catfishes
Authors: Jenkins David B.
Published: February 2005

The sacculi of five species of catfishes were studied by transmission and scanning electron microscopy. In four species, the sagitta exhibited a multifluted anterior part and a tapered posterior part; in Corydoras aeneus, however, the fluted part was absent, and a vertical component extended dorsally to terminate near the opening of the transverse canal. In all species, the otoliths had a laminar structure. An otolithic membrane was present, and hair cell bundles projected into cavities on the macular surface of the membrane. Attachments of the otolithic membrane to the neuroepithelium included short extensions of the membrane to the tallest components of the hair cell bundles of the peripheral cells and more delicate connections to the kinocilium and taller stereocilia of central cells; in addition, attachments to the microvilli of supporting cells were present. In both hair cells and supporting cells single microtubules and bundles of microtubules were present; the bundles had an orderly arrangement and were associated with cytoplasmic densities surrounding the desmosomes. The hair cells were innervated by both afferent and efferent nerve endings. Studies of the polarization of the hair cells in all species (except C. aeneus) showed that there was a single longitudinal axis that divided dorsally polarized cells from those oriented ventrally. In Doras spinosissimus and Bunocephalus bicolor, an additional line of polarization was evident in a small area in the anterior part of the macula; therefore, in these forms there was a double bipolar orientation.
Ultrastructure of the tubular nephron of the garter snake Thamnophis sirtalis
Authors: Peek William D. , McMillan Donald B.
Published: February 2005

Ultrastructural features of the tubular nephron of the garter snake, with special reference to modifications for conservation of water, were studied using transmission electron microscopy, freeze‐fracture and tracer experiments. Although a nephric loop (loop of Henle) is lacking, the tubules appear to be structurally well adapted for efficient ion and water reabsorption. The most prominent features are well developed microvilli in the proximal tubule and elaborate lateral folds, particularly in the distal tubule and collecting ducts. The latter structures are highly interdigitated, creating complex intercellular channels, perhaps facilitating transepithelial fluid transport. Only the proximal tubule actively absorbs and degrades protein tracers from the lumen. The cells of the collecting duct secrete mucus which may precipitate and bind urate salts in the lumen. This may be significant in the excretion of these salts, a process which combines maximal removal of salts and nitrogenous wastes with minimal loss of water.
Ultrastructure of the renal corpuscle of the garter snake Thamnophis sirtalis
Authors: Peek William D. , McMillan Donald B.
Published: February 2005

The renal corpuscle of the garter snake was examined using scanning and transmission electron microscopy, freeze‐fracture and tracer experiments. The renal corpuscle was small and glomerular architecture simple. The visceral epithelium was composed of irregular, highly branched podocytes with broad, interdigitating foot processes. Numerous cell junctions, including fasciae occludentes and adhaerentes, occurred between podocytes. The podocytes bore numerous microvilli which projected into the urinary space and contained large bundles of microfilaments. The podocytes lay on a basal lamina which appeared to act as a primary filtration barrier.