bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning electron microscopy of the developing alimentary canal in the chick
Authors: Lim Soo‐Siang , Low Frank N. 
Published: February 2005

AbstractFresh 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

AbstractStructures 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractEpendyma 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

AbstractThis 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

AbstractThe 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

AbstractAntibody 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractUltrastructural 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

AbstractThe 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.