bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the endometrium during the estrous cycle in the bitch
Authors: Barrau Marny D. , Abel John H. , Verhage Harold G. , Tietz W. J. 
Published: February 2005

AbstractThe endometrium of 40 cycling bitches was studied using cytological, cytochemical, and morphometric techniques. Two principal phases of growth and differentiation can be discerned. Phase one begins at the end of anestrus as serum estrogen levels begin to rise and is completed just prior to estrus. It is characterized by growth of the crypts and differentiation of the glandular epithelial cells into well‐developed, mucus‐secreting cells. Growth, initially rapid, gradually slows. The second growth phase does not begin until the middle of estrus as serum progestin levels rise and lasts nearly a week. Both hypertrophy and hyperplasia of the glandular epithelium and growth of the basal glands characterize this stage. The gland cells develop many well‐defined characteristics of absorptive and secretory cells. Another phase of growth occurs in pregnant animals at the onset of implantation. During the third week of metestrus in non‐pregnant bitches, the uterus begins to involute. Acid phosphatase and the number of lysosomes increase dramatically in the epithelial cells particularly in the basal glands. Cells lining the lumen and crypts accumulate numerous large lipid droplets.The data are discussed in relation to the clear separation of two distinct uterine functions: (1) sperm transport and maintenance and (2) production and secretion of nutritive uterine milk. Extended periods of follicular development, breeding, and preimplantation in the bitch probably impose this separation.
Ultrastructural study of mouse olfactory epithelium following destruction by ZnSO4 and its subsequent regeneration
Authors: Matulionis Daniel H. 
Published: February 2005

AbstractRegeneration of olfactory epithelium was studied at the ultrastructural level in two different strains of mice (C57B1/6J and SWR/J) following destructive changes induced by nasal irrigation with a 1% aqueous solution of zinc sulfate (ZnSO4).Three epithelial conditions were seen during the first four to 14 days following treatment: a “surface alteration” state characterized by changes at the apical ends of olfactory and columnar supporting cells, a “squamous‐metaplastic” state, and a “simple‐squamous” state. In the latter two conditions, thought to represent regenerative states, cells contained inclusions similar to secretion granules in Bowman's glands. This observation supports earlier suggestions that new epithelial cells originate from these glands. Later regenerative changes consist of differentiation of new sensory cells and columnar supporting cells in an initially disorganized epithelium. This epithelium then changes to a normal, pseudostratified organization.Regeneration of the epithelium begins earlier and proceeds more rapidly in the SWR/J strain than in C57B1/6J mice. Possibly, a genetle difference exists between strains. After 72 days the epithelium in both strains had regenerated.
Studies on the progestational endometrium of the rabbit. II. Electron microscopy, day 0 to day 13 of gonadotrophininduced pseudopregnancy
Authors: Davies J. , Hoffman L. H. 
Published: February 2005

AbstractThe fine structure of the endometrial epithelium of the pseudopregnant rabbit from the day of induced ovulation (day 0) to the 13th day is here correlated with previously defined light microscopic phases. In Phase 1 (0–1 day), in which there is a presumed “priming” of the endometrium by ovarian steroidal hormones, no changes were observed. In Phase 2 (1–3 days), in addition to mitotic activity, the epithelium showed a disappearance of the mucification and lymphocytic migration typical of Phase 1 and also of the nonpregnant or “estrous” phase, and showed other nuclear and cytoplasmic changes which probably reflect endogenous growth and protein synthesis. In Phase 3 (4–6 days), two distinct populations of reacting cells were present: (1) surface and cryptal cells investing the now folded mucosal surface, and (2) glandular cells. The first group showed characteristic dome‐like protrusions of the cytoplasm into the lumen, and also showed distinct cytoplasmic and nuclear changes which appear to be a prelude to the succeeding phase of fusion but are not necessarily secretory in type. The glandular cells, in contrast, showed cytoplasmic changes which appear to reflect active secretory activity (hypertrophy of the Golgi area, cytoplasmic vacuoles containing electron‐opaque material, etc.). This phase coincides with the maximal secretion of uterine‐specific proteins, and electron‐opaque material is abundant within the endometrial lumen. In Phase 4 (6–8 days), the surface and cryptal epithelium undergoes a transformation into multinucleated cells, the result of a process of lysis of intervening plasma membranes, the precise mechanism of which (i.e., with or without initial membrane fusion) was not determined. Cell fusion proceeded earlier and more actively mesometrially than antimesometrially. The glandular cells showed evidence of reduced secretory activity, but did not at any stage undergo multinucleate‐cell transformation. In Phase 5 (8–13 days) there was progressive fusion, and the number of nuclei per cytoplasmic sac appeared increased, presumably due to the continued action of progesterone which is maximal during this phase. Glandular cells showed further reduced secretory activity but remained columnar. Ciliation of the epithelium was sporadic in the pre‐secretory phases and rare or absent in the secretory and fusion phases; it became widespread during the phase of decline after day 14, a period which will not be included in this study. The fine structure of the ciliated cells was the same at all stages; there was no evidence for their origin from a reserve population; it is possible that they arise by modification of the multinucleated cells. Cytoplasmic crystals and intramitochondrial densities or lamellae were observed during the secretory and fusion stages, the former only in the glands, the latter in the surface and cryptal epithelium. They appear to be associated with rising or maximal progesterone secretion.
Anti‐horseradish peroxidase associated with the Golgi complex of antibody‐forming cells
Authors: Tomonaga Susumu , Schoefl Gutta I. 
Published: February 2005

AbstractObservations are reported on the localization of anti‐horseradish peroxidase in antibody‐forming cells in popliteal lymph nodes following a single injection of antigen. Reaction product, marking the site of antibody, was observed not only in the ergastoplasm and cisternae of the Golgi complex, but also in globules associated with the Golgi complex.
Renal morphology of freshwater trout
Authors: Anderson Bettina G. , Loewen Richard D. 
Published: February 2005

AbstractThe nephron of the euryhaline freshwater salmonids is composed of the renal corpuscle and the renal tubules. Throughout much of the renal corpuscle, only the lamina densa separates the fenestrated processes of the endothelial cells from the foot processes of the visceral epithelium. The renal tubule consists of five distinct segments. The neck segment is short and intermittently ciliated; it lacks the mucous cells which appear in the neck segment of some teleosts. The proximal segment bears a dense brush border and is both structurally and functionally divisible into a first and a second segment. The first portion is typified by the presence of short apical tubules, variously sized apical vacuoles, and numerous lysosomes. The second proximal segment is distinguished by the abundance and distribution of mitochondria throughout the cytoplasm. Infoldings of the basilar plasmalemma are especially prominent in this region. A ciliated intermediate segment intervenes briefly between the proximal and distal portions of the tubule. The distal segment consists of cuboidal cells which bear scattered, short microvilli, small vesicles and multivesicular bodies.Renal tissue from several species of trout was examined in order to establish the basis for a common pattern of histological and ultrastructural characteristics within the family Salmonidae. In all species examined, renal structure was very similar and could readily be compared with that previously described in other freshwater and marine species.
A complex junctional system in endothelial and connective tissue cells of the choroid plexus
Authors: Dermietzel Rolf , Schünke Dorothee 
Published: February 2005

AbstractEndothelial and connective tissue cells of the choroid plexus have been studied by the freeze‐etching technique. The endothelial cells of pre‐ and postcapillary segments are coupled by a complex junctional system consisting of a combination of tight and gap junctions. Connective tissue cells revealed the same intercellular contacts. Furthermore two different types of gap junctions occurring in membranes of the connective tissue cells are described.
Ultrastructural observations of pineal gland capillaries in four rodent species
Authors: Matsushima Shoji , Reiter Russel J. 
Published: February 2005

AbstractThe fine structure of the capillaries of the pineal glands of the rat, mouse, chinchilla and ground squirrel were investigated. The pineal endothelial cells in the rat, mouse and ground squirrel were often composed of attenuated cytoplasmic portions which contained numerous fenestrations, in contrast to pineal capillaries in the chinchilla which were lined by thick non‐fenestrated endothelial cells. Marked morphological differences were also apparent in terms of the types of vesicles within the cytoplasm and abutting on the cell surface of pineal endothelial cells from the various specius investigated. The interendo‐thelial junctions exhibited remarkable species differences with the chinchilla pineal possessing typical tight endothelial junctions while those in the rat, mouse and ground squirrel lacked such endothelial cell associations. Generally, capillary lining cells in the chinchilla pineal resembled similar cells within the brain, while endothelial cells in pineal glands of rat, mouse and ground squirrel were more typical of those found in other endocrine organs. Species differences in the structure of the pineal capillaries may represent physiological differences as well.
Ultrastructural observations on the maturation of the placental labyrinth of the golden hamster (days 10 to 16 of gestation)
Authors: Carpenter Stanley J. 
Published: February 2005

AbstractMorphogenesis of the labyrinthine part of the chorioallantoic placenta of the golden hamster between day 10 of gestation and term (day 16) was studied by light and electron microscopy. During this period the labyrinth increases greatly in both size and complexity. Trabeculae of the labyrinth, thin partitions composed of trophoblastic tissue and fetal capillaries which delimit the maternal blood spaces, apparently proliferate both by appositional and interstitial growth. From the time of its formation (day 9 of gestation) until term the labyrinth is hemotrichorial in organization (i.e. three layers of trophoblast separate maternal blood from fetal capillaries). Both the inner and intermediate layers of trophoblast (layers III and II, respectively) are syncytial. The outer trophoblastic layer (III), which is in direct contact with maternal blood, remains cellular, although many of its component cells grow to giant cell dimensions (“labyrinthine giant cells”). Between the tenth and fourteenth days of gestation the anatomical barrier to diffusion between maternal and fetal blood is progressively reduced. This is accomplished both by gradual attenuation of the trophoblastic layers and fetal capillary endothelium and by the formation of discontinuities (gaps) in layer I, and diaphragmed fenestrae in fetal capillary endothelium. The labyrinthine placental barrier is fully developed and probably attains maximal functional efficiency by the fourteenth day of gestation. Late in the fifteenth day of gestation, a few hours before parturition, distinct degenerative changes are apparent in the trophoblastic layers and fetal capillaries of the trabeculae. The factors responsible for initiating these degenerative changes and the onset of parturition are still controversial.
Cell population dynamics of periodontal ligament stimulated with parathyroid extract
Authors: Roberts W. Eugene 
Published: February 2005

AbstractYoung adult rats were injected with parathyroid extract (PTE). Periodontal ligament (PDL) adjacent to a previously resorbing alveolar bone surface was divided into four zones numbered I to IV, from bone to cementum. Zones I and IV were within 25 mμ of the bone and cementum surfaces, respectively, while a line bisecting the center of the PDL separated Zones II and III. A net increase of about 16 total nuclei in all zones was observed during the first five hours after PTE administration. Since local mitosis accounted for no more than two nuclei, approximately 14 cells apparently migrated into the area. Over the first five hours Zones I and II combined showed a 21‐cell increase, being apparently the scle recipients of cells migrating into the field (14) plus approximately seven more from Zone III, which lost cells during the time period. The concurrent histological observation in Zone II, of increased intravascular monocytes and perivascular macrophages during the first five hours, suggests cells are migrating into Zone II via vascular channels. The data suggest two sources for increased PDL cellularity associated with stimulated osteoclast histogenesis: (1) local PDL cellular proliferation and (2) influx of migrating cells (probably through vascular channels) during first five hours after PTE.
Ultrastructure of the early ovary and testis in pig embryos
Authors: Pelliniemi Lauri J. 
Published: February 2005

AbstractPig embryos aged 26–27 days were used for an ultrastructural study of the early ovary and testis. Sex was identified by both chromosomal analysis and gonadal histology, with consistent results.The gonads occupied their original site in the medial coelomic angles in both sexes. The female gonad was composed of three tissues: the surface epithelium, the gonadal blastema and the mesenchyme. The gonadal structure was similar to that seen earlier at the age of 24 days. At 26 days the testis had distinctly differentiated into four tissues. The new components were the testicular cords and the interstitium, both derived from the gonadal blastema. The testicular cords resembled anastomosing sheets more than cords.The ultrastructure of the tissues and their cell types are described and compared to the previous indifferent stage at the age of 24 days. The cells of the surface epithelium, of the primitive cords, of the mesenchyme, and the primordial germ cells had an ultrastructure that was similar in both sexes. The sustentacular cells of the testicular cords resembled the primitive cord cells and the spermatogonia were similar to the primordial germ cells. No Leydig cells were present yet.The process of testicular differentiation is described on the basis of the present and a previous study, and a new hypothesis, based on the vascular organization, is presented.
Cortical cytoplasm and configurational changes of RGC‐6 cells exposed to cytochalasin B
Authors: Bondareff William , Tuttle Richard L. 
Published: February 2005

AbstractRGC‐6 cells, grown to confluency in monolayer cultures, are typically fusiform. In sections of these cells, fixed in situ and examined in the electron microscope, a discontinuous zone of cortical cytoplasm (5–7 nm wide), was found subjacent to the plasma membrane of the free surface. It was composed largely of 5–7 nm microfilaments distributed in an apparently irregular nework and appeared to comprise a discrete zone separating the plasma membrane from the underlying endoplasm.Following incubation with cytochalasin B (5 μg/ml), the configuration of the cells changed markedly. The perikaryal cytoplasm appeared to swell, while the cellular processes became attenuated and often terminated in flower‐like tips. Although more discontinuous and somewhat less dense, the fine structure of the cortical cytoplasm appeared little affected by incubation with cytochalasin B for one hour. By 48 hours no zone of cortical cytoplasm was found. Subplasmalemmal microfilaments were no longer identifiable and endoplasmic organelles were found in direct contact with the plasma membrane of the free surface, which appeared to have collapsed onto the underlying endoplasm.The change in cell configuration resulting from exposure to cytochalasin B occurred at 37°C but not at 4°C, suggesting a dependency on metabolic activity. It did not, however, appeared related directly to protein synthesis. Whereas incorporation of 3H‐leucine was decreased to 46.9% and 62.9% of control values after one hour or two hours exposure to cytochalasin B, respectively, no change was found after 24 or 48 hours. It is suggested that the effect of cytochalasin B on cell form, which appeared not to be a direct effect on either protein synthesis or subplasmalemmal microfilaments, may represent a primary response of the cortical cytoplasmic matrix.
Structural modification of Schwann cells in the pancreatic islets of the dog
Authors: Smith Phillip H. 
Published: February 2005

AbstractIn dog pancreatic islets, Schwann cells not only ensheath autonomic nerves but also have cytoplasmic processes that are contiguous with large expanses of the islet surface. These processes are interposed between the islet basal lamina and the endocrine parenchyma. This structrual modification of Schwann cells may play a role in the neural control of islet function.
Light and electron microscopic study of the degeneration and early regeneration of olfactory epithelium in the mouse
Authors: Matulionis Daniel H. 
Published: February 2005

AbstractDegeneration and early regeneration of olfactory epithelium from two strains of mice was studied at the light and electron microscopic levels from 12 hours to 3 days following nasal irrigation with 1% aqueous solution of zinc sulfate (ZnSO4) (a compound known to selectively damage olfactory epithelium). Distinct patterns of degeneration and stages of regeneration were evident following treatment. During the first 24 hours after treatment three progressive manifestations of the degenerative process were seen: (1) a relatively mild condition which was characterized by surface irregularities produced by cell protrusions, highly vacuolated cytoplasm, presence of large lysosome‐like bodies and prominent intercellular spaces, (2) a more severe condition in which large areas of the epithelium were detached from the basement membrane and cellular debris was present in the nasal chamber, and (3) a condition of total or near‐total denudation of the epithelium of olfactory mucosa. The basal lamina was continuous and intact in most regions and the integrity of the subjacent connective tissue was mostly well‐preserved. Nerve bundles of the fila olfactoria were noted in varying degrees of degeneration during the course of the experiment. The most advanced neural degeneration was seen 24 to 72 hours after treatment. Onset of regeneration was suggested by the appearance of a simple squamous layer of cells above the basement membrane 48 to 72 hours after treatment. In addition to the simple epithelium a stratified epithelium consisting of two to four cell layers was also observed at this time. Glandular cells, containing secretory granules identical to those in Bowman's glandular cells, were noted in an apparent process of migration from the lamina propria into the stratified epithelial layer. The last mentioned observation supports the proposition that new supportive epithelial cells originate from cells of Bowman's gland.
Scanning electron microscopic study of the effects of pressure on the luminal surface of the rabbit aorta
Authors: Swinehart Paul A. , Bentley David L. , Kardong Kenneth V. 
Published: February 2005

AbstractThe effects of pressure on the luminal surface of the rabbit aorta were investigated using the scanning electron microscope. The method followed was perfusion under hydrostatic pressure of a section of thoracic aorta, in vitro. The characteristic ridged pattern seen in sections fixed at zero hydrostatic pressure was to a large extent eliminated when fixation occurred at pressures equivalent to those experienced by the aorta at systole or diastole. This study suggests that the spiral ridged pattern is dependent upon the fixation pressure and may not be present in a normally functioning artery. Any attempts to characterize or interpret the appearance of the luminal arterial wall must take into account the effects of pressure.
The transmural passage of blood cells into myeloid sinusoids and the entry of platelets into the sinusoidal circulation; a scanning electron microscopic investigation
Authors: Becker Robert P. , De Bruyn Peter P. H. 
Published: February 2005

AbstractScanning electron microscopic observations of rat bone marrow reveal that the sinusoidal wall is continuous and has no permanent patent apertures allowing free communication between the extravascular and intravascular myeloid compartments. Blood cells migrate into the sinusoids by perforating the endothelial cell body.Platelets are derived from long intrasinusoidal “proplatelet” processes which originate from the cell body of extravascularly located megakaryocytes. Proplatelet processes frequently occur in clusters, with the probability that all processes in a cluster arise from a single megakaryocyte. The release of platelets into the circulation may be initiated by local constriction along these processes, at which places either individual platelets or larger segments of proplatelet cytoplasm are pinched off. The larger segments may subsequently undergo further fragmentation into individual platelets.
The hypothalamic magnocellular neurosecretory system of the guinea pig. III. Ultrastructure of the fetal neural lobe
Authors: Silverman A. J. , Desnoyers P. 
Published: February 2005

AbstractThe ultrastructure of the fetal guinea pig neural lobe was studied from day 40 to day 60 of gestation. Pituitaries were taken every five days and at least four glands from each gestational period were examined.Bundles of nerve fibers had invaded the periphery of the gland on day 40. By day 50 axon profiles were distributed throughout the entire posterior pituitary though pituicyte processes continued to act as a barrier between axons and the perivascular space of capillaries. Neural processes established contact with the capillaries between days 55 and 60.Neurosecretory granules (NSG) were present within a few axons on day 40. The number of axons with NSG and the total quantity of granules increased gradually throughout fetal development. Electron‐lucent granules (microvesicles) were observed infrequently until the day of birth. A population of dense‐cored vesicles, 70–80 mμ in diameter, was present from day 50 onward; a second population with larger diameters was also present throughout the developmental sequence and these increased from 90–130 mμ in diameter to 170–220 mμ in diameter between days 40 and 60.The presence of neurosecretory granules is discussed in relation to the onset of synthesis and storage of neurohypophysial hormones.