bluuebunny/crossref_metadata_2025_split huggingface dataset:
A fine structural study of human oral epithelium separated from the lamina propria by enzymatic action
Authors: Scaletta Lawrence J. , MacCallum Donald K. 
Published: February 2005

AbstractIncubation of human oral mucosa in physiological solutions containing proteolytic enzymes permits separation of the preparation into its epithelial and connective tissue components. Trypsin, collagenase and elastase were utilized to effect epithelium‐connective tissue separation. Elastase was the most suitable in that a reliable separation of the epithelium from the connective tissue occurred at the lamina lucida (the electron‐lucent zone between the basal cell and basal lamina) with only minimal alteration of the epithelium. The most common change observed in separated epithelium was the formation of cytoplasmic protrusions or blebs on the inferior surface of the epithelial basal cell. Bleb formation was quite extensive when preparations were incubated one to two hours beyond the point where the epithelium could be separated from the connective tissue. With prolonged incubations inferior aspects of epithelial basal cells demonstrated the formation of an entirely new cytoplasmic front apparently resulting from fusion of membranes and subsequent confluence of the cytoplasm contained within the blebs. Individual hemidesmosomes or small lengths of the original inferior epithelial basal cell membrane became enclosed in membrane‐bound vacuoles within the cytoplasm of the epithelial basal cell. These vacuoles were shown to have been interiorized by the absence of a ruthenium red reaction product within the vacuolar spaces. Bleb formation was shown to be strictly enzyme‐induced since intact specimens demonstrated extensive basal cell blebbing following prolonged incubation. Occasional desmosomes were broken and the component halves interiorized in membrane‐bound vacuoles within the cell cytoplasm. Alterations observed in epithelial basal cells as a consequence of exposure to exogenous proteolytic enzymes mimic alterations observed in many disease processes and during certain stages of development.
A study of fine structural changes in the cartilage‐to‐bone transition within the developing chick vertebra
Authors: Crissman Robert S. , Low Frank N. 
Published: February 2005

AbstractForty‐eight chick embryos were killed at 9–16 days of incubation age. Tissue was obtained from the fourth or fifth cervical vertebra, immersed in Karnovsky's fluid, post‐fixed in osmium tetroxide, dehydrated in ethanol, stained “en bloc” with uranyl acetate in ethanol, and embedded in Epon 812. Vertebrae were oriented for cross‐sectional microtomy in cephalic to caudal sequence. Thin sections were stained with uranyl and lead salt solutions saturated with tribasic calcium triphosphate to prevent decalcification.Chondrocytes within the cartilaginous vertebral body occur in various stages of degeneration without orderly arrangement. Both reversible and irreversible stages are found at the cartilaginous resorption front. Electron‐lucent osteoid and mineralization appear in the intercellular matrix at about 12.5 days. Rapidly invading blood vessels form a highly variable resorption front and irregular marrow cavity. Capillaries with accompanying cells border on the front, but else‐where open capillaries allow blood elements to be in direct contact with cartilage. Chondroclasts are associated with small areas of calcified cartilage. At about 14 days trabeculae are formed at the resorption front by osteoblasts which deposit bone osteoid on uncalcified cartilaginous matrix. The matrix is eroded away. A free trabecula of bone without a core of calcified cartilaginous matrix remains.Basic differences between developmental growth processes in the epiphyseal plate and vertebral body may stem from the large amount of uncalcified cartilaginous matrix at the latter's resorption front.
Electron microscope immunohistochemical localization of vasopressin in the hypothalamus and neurohypophysis of the normal and brattleboro rat
Authors: Leclerc Rachel , Pelletier Georges 
Published: February 2005

AbstractUsing an immunoperoxidase technique at the ultrastructural level, vasopressin was localized in the axons of both the supraoptic and paraventricular nuclei, in the internal zone of the median eminence and the posterior pituitary but not in the perikarya of the neurosecretory neurons. A complete absence of histochemical reaction was found in the hypothalamo‐neurohypophyseal tract of the rat with hereditary hypothalamic diabetes insipidus (Brattleboro strain).
Molar development in the Mongolian gerbil (Meriones unguiculatus)
Authors: Hiatt James L. , Gartner L. P. , Provenza D. V. 
Published: February 2005

AbstractOdontogenesis was studied in the Mongolian gerbil (Meriones unguiculatus) molar from the dental lamina stage of development to the appositional stage. Fertilization, determined by vaginal lavage technique, was counted as day 0. Prior to the eighteenth post‐coital day no dental primordia could be detected. Beginning on day 18, pregnant females were sacrificed and the fetuses were decapitated. The heads were frozen and sectioned in a cryostat. The tissue was stained, dehydrated, cleared, and covered. Light microscopy was utilized in evaluating molar odontogenesis. Odontogenesis of the molar began at the dental lamina stage on day 18 followed by the bud stage on day 19 prenatal. The cap stage of development was observed on day 19 or 20. Development of the bell stage was noted on day 22. By the fourth postnatal day, the first molar had reached the appositional stage of development. Development of molars in the gerbil resembles that in other rodents.
Ultrastructural observations of anterior pituitary somatotrophs following pituitary portal vessel infusion of dibutyryl cAMP
Authors: Wilbur Donald L. , Worthington W. Curtis , Markwald Roger R. 
Published: February 2005

AbstractDibutyryl cyclic adenosine monophosphate (4.6 x 10−7M) was infused with a microcannula into hypothalamo‐hypophysial stalk portal vessels of adult male rats. Anterior pituitary glands were prepared for electron microscopic examination at 1, 5, 15, 30 and 60 min after microinfusion. Ultrastructural observations give evidence of stimulated protein synthesis, and emiocytosis. Emiocytosis occurs at 1, 5 and 15 min only. Evidence of protein synthesis does not develop until 15 min. It persists through the 30 min time period. These observations suggest that dbcAMP may be a potent stimulus to protein synthesis, and may be a sufficient stimulus for emiocytosis.
The growth of infant hearts grafted to young and adult rats
Authors: Dittmer J. E. , Goss R. J. , Dinsmore C. E. 
Published: February 2005

AbstractHearts from infant rats were grafted to the abdominal cavities of infant or adult hosts by end‐to‐side anastomosis of the graft's aorta to the host dorsal aorta, and of the donor's pulmonary artery to the inferior vena cava of the host. In such transplants, circulation through the heart bypassed the left atrium and ventricle. Four months after operation, the grafts had grown to normal adult sizes and their right ventricles had hypertrophied commensurate with the left side.
Ultrastructure of the placenta of antarctic seals during the first third of pregnancy
Authors: Sinha Akhouri A. , Erickson Albert W. 
Published: February 2005

AbstractThe chorioallantoic placenta from six crabeater seals (Lobodon carcinophagus) with fetuses from 15–180 mm crown rump length (CRL), and two leopard seals (Hydrurga leptonyx) with fetuses 76 and 86 mm CRL was lobulated, zonary, labyrinthine and endotheliochorial. The fine structure of the placenta was essentially similar in both species. Maternal capillaries of the labyrinth had attenuated endothelial cells unlike the fissiped carnivores. They were surrounded by an outer syncytiotrophoblast, incomplete inner cytotrophoblast, and a core of mesenchymal tissue containing fetal vessels. In general, the cytotrophoblastic cells were less electron‐opaque than the syncytium; the former possessed abundant free ribosomes, while the latter had many nuclei, mitochondria, and numerous strands of rough endoplasmic reticulum. Mitotic figures were observed only in the cytotrophoblast. Plasma membranes between the trophoblastic layers had interdigitating processes which showed many desmosomes along the intercellular spaces, whereas membranes surrounding the maternal capillaries were usually smooth. In the limb‐bud stage embryo, the syncytiotrophoblast had thick and thin areas which became progressively attenuated in older fetuses. Instances of intratrophoblastic fetal capillaries were observed in seals with fetuses of 40 mm CRL and older, with consequent greatly thinned placental barriers. By Perl's reactions, Turnbull's method, and electron microscopy, rows of granular bodies positive for iron were demonstrated along the basement membrane of the trophoblastic cells and in the mesenchymal cells of the crabeater seals, but not the leopard seals. Furthermore, it is suggested that the deposits of granular bodies show the sites of iron storage in the placentas. In the limb‐bud stage embryo the hematome borders and isolated pouches of the central hematome were observed. The central hematome was antimesometrial. The hematomes were lined by columnar cytotrophoblastic cells which phagocytized extravasated maternal blood and absorbed histiotrophic material.
Effects of Cytochalasin‐B and colcimide on cells in muscle cultures
Authors: Holtzer H. , Croop J. , Gershon M. , Somlyo A. 
Published: February 2005

AbstractCytochalasin‐B (CB) induces cells to contract. This contraction is biphasic. The rapid response peaks in 30 minutes and is followed by a slower contraction that leads to the “arborized” configuration. If fully arborized cells are removed from CB and exposed to colcimide they are induced to form twisting, birefringent bands. These bands consist of massive numbers of 100 Å filaments.
A discrepancy between measurements of bone resorption in vivo and in vitro in newborn osteopetrotic rats
Authors: Marks Sandy C. 
Published: February 2005

AbstractBone resorption in newborn osteopetrotic rats and their normal littermates was measured in vivo and in vitro with different results. The resorption measured in vivo was that induced by injection of parathyroid extract after labeling bone matrix with 3H. Resorption was measured in vitro, by a commonly used method, as the release into the culture medium of 45Ca and 3H previously incorporated in vivo into bone mineral and matrix respectively. In osteopetrotic rats resorption induced by parathyroid extract in vivo was 34 percent less than in littermate controls, whereas the resorption measured in vitro was 26 percent greater in bone from osteopetrotic rats. In addition, the hypercalcemia induced by injections of parathyroid extract was only half as great in osteopetrotic rats as in normal littermates.Acid phosphatase appears to be important in bone resorption; osteoclasts are rich in the enzyme and it is released from them during bone resorption. Newborn osteopetrotic rats have more osteoclasts which are richer in acid phosphatase than normal littermates. Therefore, it is proposed that the enhanced resorption found in bone from osteopetrotic rats in vitro is the result of release of this excessive acid phosphatase from osteoclasts under the conditions of culture and does not truly reflect resorption in vivo.
The effect of supernumerary cartilaginous implants upon rabbit ear regeneration
Authors: Grimes L. Nichols 
Published: February 2005

AbstractFull thickness holes through rabbit ears are filled from their margins by the regeneration of missing tissue, including the ear's cartilaginous sheet. However, no regeneration of ear tissue occurs if the cartilaginous sheet is removed. If a second sheet of cartilage is implanted into the ear, only one layer of cartilage differentiates in the regenerate. Therefore, although the original cartilaginous sheet is necessary for chondrogenesis in the regenerate, it does not dictate morphogenetic information to the blastema.
Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine II. Mucous cells
Authors: Cheng Hazel 
Published: February 2005

AbstractThe mucous cell population of duodenum, jejunum and ileum was investigated in the light and electron microscopes with the help of radioautography in mice sacrificed at various times after single injection or continuous infusion of 3H‐thymidine.Mucous cells are characterized by globules of mucus and by dilated cisternae of rough endoplasmic reticulum. Two subgroups of mucous cells, one called common and the other granular, may be identified. The granular mucous cells differ from the common ones by the presence of small dense granules embedded within the mucous globules. Each subgroup is further divided into immature oligomucous cells containing few mucous globules, and mature goblet cells with a large accumulation of mucous globules.Common and granular oligomucous cells are found exclusively in the crypt, mainly within the lower mid‐crypt, whereas the corresponding two types of goblet cells are present in the upper part of the crypts and in the lower part of the villi. Only common mucous cells are observed in the upper part of the villi.The two types of oligomucous cells, but not goblet cells, have the ability to take up 3H‐thymidine and divide. Electron microscopic radioautography demonstrates that, as oligomucous cells migrate upwards, they transform into goblet cells. The latter then migrate to the villus epithelium.In the case of granular mucous cells, this migration is associated with a gradual loss of the characteristic dense granules, so that the granular goblet cells reaching the upper part of the villi become common goblet cells. The goblet cells in the villus epithelium, regardless of their origin, ascend towards the villus tips where they are lost through the extrusion zones.The turnover time of common mucous cells is about three days, as for columnar cells; and that of granular mucous cells, somewhat shorter. In both cases, the divisions of oligomucous cells account only for the production of about half the mucous cells present. Hence, the other half must be derived from precursors other than oligomucous cells. Since a few crypt‐base columnar cells contain the odd mucous globule, they are suspected of being the precursors of the two types of oligomucous cells and, through them, of the entire mucous cell population.
Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine V. Unitarian theory of the origin of the four epithelial cell types
Authors: Cheng Hazel , Leblond C. P. 
Published: February 2005

AbstractThe previous articles of this series provided presumptive evidence that the four main differentiated cell types in the epithelium of the mouse small intestine: villus columnar, mucous, entero‐endocrine, and Paneth cells, originate from the same precursor, the crypt‐base columnar cell. In the present work, direct evidence was obtained in support of this view. It was first found that crypt‐base columnar cells phagocytose non‐viable cells in their vicinity, with the result that a large phagosome appears in the cytoplasm. Such phagosomes were then used as markers to follow the evolution of crypt‐base columnar cells.In normal control animals, a rare crypt‐base columnar cell includes a large phagosome containing Paneth cell remnants. By six hours after injection of two μCi 3H‐thymidine per g body weight, a fair number of crypt‐base columnar cells include a different type of phagosome containing labeled nucleus and granulefree cytoplasm, which is attributed to phagocytosis of a labeled crypt‐base columnar cell killed by beta‐radiation from the incorporated 3H‐thymidine.By 12 hours after 3H‐thymidine injection, phagosomes have appeared in partly differentiated mid‐crypt columnar cells and oligomucous cells; by 18–24 hours, in fully differentiated columnar cells and in Paneth cells; and by 30 hours, in an entero‐endocrine cell. Since phagosomes are first found in crypt‐base columnar cells and only later in the four differentiated cell types, it is concluded that crypt‐base columnar cells transform into cells of these four types and, therefore, behave as the stem cells of the epithelium.The finding of rare epithelial cells containing two different types of secretory material (either mucous globules and entero‐endocrine granules, or mucous globules and Paneth cell granules) confirms that the stem cells are multipotential. These findings support the Unitarian Theory of epithelial cell formation in the small intestine.
Passage of red blood cells through the sinusoidal wall of the spleen
Authors: Cho Yongock , De Bruyn Peter P. H. 
Published: February 2005

AbstractThe migration of blood cells across the wall of splenic sinusoids has been studied by means of serial sections in rats inoculated with murine erythroblastosis virus (MEV). The sinusoidal walls of the normal spleen have no permanent openings. In the normal spleen, mature red blood cells and blood cells in the latest stages of maturation can be seen in diapedesis. The predominant form of transmural migration is intercellular. In MEV‐inoculated animals, in which there is a vigorous erythroblastic proliferation, large numbers of erythroblasts are in transmural passage. Serial sections show that these cells migrate through the cytoplasm of the endothelial lining cells. On the basis of these observations, it is suggested that the transcellular mode of migration may be related to the delivery of newly formed red blood cells into the circulation while the intercellular mode may be part of the mechanism by which the spleen controls the removal of red cells from the circulation.
Anomalous patterns of mammalian oocyte maturation and fertilization
Authors: Thompson Robert S. , Zamboni Luciano 
Published: February 2005

AbstractThis report illustrates some of the errors that may occur during in vivo and in vitro maturation and fertilization of mammalian ova, considers the possible mechanisms accounting for their occurrence, and discusses their functional consequences. Included in the description are anomalies of oocyte and follicular development, i.e., multinucleated oocytes, polyovular follicles, and aberrations of zona pellucida formation. Also considered are deviations from the normal process of oocyte maturation such as chromosomal anomalies, development of abnormal nuclear structures (subnuclei), inhibition of polar body formation and aberrations of polar body structure. Anomalies of the process of fertilization such as polyspermia, sperm penetration into polar bodies, and development of multinucleated blastomeres in two‐cell embryos are also described.
Effect of gonadotropins on ovulation and ovarian histology in the immature mongolian gerbil
Authors: Fischer Theodore V. , Fisher Don Lowell 
Published: February 2005

AbstractThe present study is an analysis of the effects of super‐ovulatory doses of gonadotropins on the rate and time of ovulation and ovarian histology in immature gerbils. Groups were treated with various combinations of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG). The maximum superovulatory response followed treatment with 10 IU PMSG and 20 IU HCG. High dosages of PMSG inhibited superovulation, as did some combinations involving the highest dose of HCG. Entrapment of ova within corpora lutea was common in groups receiving high doses of either gonadotropin. Luteal regression, appearing by day 3, occurred often in groups receiving high doses of HCG. A dose of 10 IU PMSG and 5 IU HCG resulted in both a near maximal superovulatory response and the least abnormal ovarian alteration.
Presence of cells combining features of two different cell types in the colonic crypts and pyloric glands of the mouse
Authors: Nabeyama A. 
Published: February 2005

AbstractA small number of epithelial cells which combine features of two cell types were observed in the descending colon and pyloric stomach of the mouse.In the descending colon, where the base of the crypts is mainly composed of poorly differentiated “vacuolated” cells, a few of these cells contain, besides the characteristic “vacuoles,” mucous globules identical to those in mucous cells or, less frequently, dense granules such as are found in entero‐endocrine cells. Because there is evidence that the poorly differentiated vacuolated cells give rise to the other cells of the epithelium, those which also contain mucous globules or dense granules are likely to be differentiating into mucous cells or enteroendocrine cells respectively.In the pyloric stomach, where the glands are mainly composed of mucous cells, some of which are poorly differentiated, a few of the latter exhibit, besides the mucous globules, entero‐endocrine type granules or features of caveolated cells. It is likely that the poorly differentiated mucous cells give rise to the other gland cells; and, therefore, those mucus‐containing cells which also display dense granules or caveolated cell features are taken to be differentiating into entero‐endocrine or caveolated cells respectively.Most of the cells containing two kinds of secretory materials are believed to be stem cells which initially contain a few vacuoles (colon) or mucous globules (pylorus) but are differentiating into a cell containing a different type of secretion. Rare observations of two kinds of secretory materials in a mature cell suggest that the transitional period may be prolonged, perhaps indefinitely.
Phagocytosis of degenerating germ cells by follicle cells in fetal guinea pig ovaries
Authors: McNamara Nancy , Black Virginia H. 
Published: February 2005

AbstractVirus‐like particles (80 mμ to 100 mμ in diameter) occur in the endoplasmic reticulum of germ cells in the ovaries of fetal guinea pigs, and are confined to this population of cells. Using these particles as a marker, the phagocytosis of degenerating germ cells by somatic cells in the cortex of the ovary was traced.
The genesis of cell types in the adenohypophysis of the human fetus as observed with immunocytochemistry
Authors: Baker Burton L. , Jaffe Robert B. 
Published: February 2005

AbstractHypophyses of 21 human fetuses, ranging in gestational age from 6 to 23 weeks, were studied by immunocytochemical and histological staining to ascertain (1) the time of origin of specific cell types and (2) the development of parenchymal cell zonation in the pars distalis. No hormones were identified at six weeks. Probable corticotrophin‐containing cells appeared at seven weeks. Somatotrophs were observed first at 10.5 weeks; correlation with other reports indicates that they appear at eight to nine weeks. Melanotrophs were detected at 14 weeks; the cells containing melanotrophin were far fewer than corticotrophs. The youngest fetus to possess gonadotrophs was 10.5 weeks old. In all specimens gonadotrophs (LH‐cells) stained well with immunocytochemical procedures but poorly with histological methods. Thyrotrophs first occurred at 13 weeks.Zonal distribution of cell types in the pars distalis was evident almost from the time of their appearance. Somatotrophs were most numerous laterally and immediately anterior to the residual cleft. At 10.5 weeks corticotrophs were confined chiefly to the borders of vascularized connective tissue (trabeculae) and to the lateral peripheral region of the pars distalis. Thyrotrophs appeared chiefly in the anteromedian zone, particularly in its superior portion, but were found laterally also. In the older specimens, gonadotrophs generally occurred throughout the pars distalis but were less numerous near the trabeculae and in the anterolateral region.There was good correlation between the time of appearance of various cell types and published data on secretory capacity of the gland.