bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oocytogenesis in rabbits. The role of neogenesis in the formation of the definitive ova and the stability of oocyte DNA measured with tritiated thymidine
Authors: Kennelly J. J. , Foote R. H. 
Published: February 2005

AbstractA series of six thymidine‐methyl‐H3 (thy‐H3) injections, one every 12 hours, was administered to 35 Dutch‐belted female rabbits (does) commencing on the day of their birth. Seventeen of the does were unilaterally ovariectomized as follows: five does at 4 and 12 weeks of age, five does at 4 and 20 weeks of age, five does at 12 and 20 weeks of age and two does at 4 and 40 weeks of age. Autoradiographs of ovarian tissue were prepared, up to 600 oocytes per ovary were randomly chosen and the silver grains associated with the oocyte nuclei recorded. The mean grain counts decreased significantly (P < 0.05) from 4 to 12 weeks, 13.5 vs. 10.1, and from 4 to 20 weeks, 14.7 vs. 11.4. However, the mean grain counts did not differ significantly (P > 0.1) between 12 and 20 weeks of age, 10.5 vs. 9.6. Although the mean grain count decreased between 4 to 40 weeks of age 21.5 vs. 14.6, the number of replications was too few to detect significant differences (P > 0.1). At 40 weeks of age 91% of the oocytes were still labeled. The reduction in grain counts from 4 to 12 weeks of age was attributed to the non‐random degeneration of the older, more highly labeled oocytes located deep in the cortical zone. The lack of significant differences between grain counts at 12 and 20 weeks of age suggests that (1) during this interval the desoxyribonucleic acid (DNA) is metabolically stable and (2) significant de novo oocyte formation did not occur. Nine rabbits were superovulated at 20 weeks of age and of the 217 ova recovered 82.5% were radioactive. This was similar to the 89.8% radioactive oocytes observed in the ovaries of the same animals.Artificial insemination of the remaining nine does at 35 and 60 weeks of age resulted in normal litters and superovulation and artificial insemination of this group at 52 weeks of age produced 73.8% radioactive ova.Five Dutch‐belted does injected at four weeks of age with thy‐H3 at the same rate and interval as the day‐old rabbits showed a slight incorporation of the isotope into both oocyte nuclei and cytoplasm suggesting that most of the incorporation was not related to any synthesis of new chromosomal DNA. A single thy‐H3 injection into three 20‐week‐old does did not result in appreciable uptake of the isotope by oocyte nuclei, although many nuclei of parenchymal cells in the ovary were highly labeled.The results conclusively support the view that most, if not all definitive ova are formed at birth and de novo oocytogenesis does not occur in the post‐pubertal rabbit.
An electron microscopic investigation of osteogenesis in the embryonic chick
Authors: Decker Jay Donovan 
Published: February 2005

AbstractCell‐matrix and bone‐matrix relationships have been studied by electron microscopy in the diaphysis of chick embryo tibio‐tarsus. Osteoblasts within the periosteum possess cytoplasmic machinery characteristic of cells involved in protein synthesis. They contain abundant ergastoplasm, and an extensive Golgi apparatus. Small vesicles are associated with the juxtanuclear Golgi apparatus as well as with the extensive ergastoplasm. This suggests that the mechanism of protein synthesis and its transfer to the external milieu may be similar to that of other protein secreting cells, the fibroblast, the odontoblast and the chondroblast.A rather wide variation in collagen fibril diameter is seen in those fibrils located between the osteoblasts and the initial ossification area. The first nucleation of apatite crystals is seen as random aggregations distinct and separate from the collagen fibrils. This appearance is independent of section orientation since there appeared to be no difference between sections oriented at right angles to or parallel with the diaphysis' long axis.The observations of this study are consistent with proposed mechanisms for the nucleation phenomenon involving the ground substance and collagen fibrils. In addition, the observations suggest a concept of cellular control over the extracellular environment effecting the initial crystal nucleation. The morphologic evidence indicates that the molecular arrangement of collagen as fibrils probably does not provide the mechanism for apatite crystal nucleation.
Differentiation of adrenal cortex‐like tissue at the hilum of the gonads in response to adrenalectomy
Authors: Seliger William G. , James Blair A. , Mossman H. W. 
Published: February 2005

AbstractFollowing bilateral adrenalectomy, the adrenal cortex‐like cells which appear in the ovaries of the 13‐lined ground squirrel are in close relationship to the epithelial remnants of the rete ovarii and the medullary cords. Identical cells form in the bilaterally adrenalectomized male around the efferent ductules of the testes.Histochemical tests on these periductular cells gave positive results with polarized light, Sudan Black stain, ultraviolet light, and the Schultz test — all comparable to normal adrenal cortex cells.Electron microscopic studies of the periductular cells showed them to have ultrastructural characteristics of a steroid secreting cell.Male and female animals adrenalectomized a year before and maintained on tap water died within four days when the gonads and adnexa were removed. Male animals adrenalectomized a year before and maintained on tap water survived actively for two weeks when the testicles were removed, provided that the efferent ductules and surrounding adrenal cortex‐like cells were left in place. These animals died within four days after the adnexa were removed.The periductular cells were incubated with radioactively tagged progesterone which showed that these cells secrete corticosterone, the normal primary corticosteroid of this animal, and desoxycorticosterone which functions as a combination glucocorticoid and mineralocorticoid.
The changing pattern of basophilia in the mouse uterus from mating through implantation
Authors: Smith Lois Jean 
Published: February 2005

AbstractChanges in RNA localization and concentration in mouse uteri taken from one‐half to seven and one‐quarter days after mating were visualized as changes in basophilia following staining by a histochemical method specific for RNA. The basophilia of the luminal epithelium falls abruptly between one‐half and two days and is still lower at two and three‐quarter days. By 2 and three‐quarter days, however, that of the stroma and especially that of the subepithelial endothelial cells is increasing. A further slight increase is found at three and three‐quarter days and by four days, a band of subepithelial stromal cells, wider in the antimesometrial than in the mesometrial portion of the uterus, is highly basophilic. At four and one‐quarter days, when a distinct decidual reaction is evident, cells in the primary decidual zone are less basophilic than at four days. During the remaining period of observation, cells in different regions of the uterus show increased and often, later, decreased basophilia. It was concluded that these results are in complete accord with those from a recent biochemical study of changes in RNA in the intact rat uterus during the interval from induction of pseudopregnancy through deciduoma formation if the difference in timing in the two species is taken into account.
Constant cell populations in normal, testosterone‐deprived and testosterone‐stimulated levator ani muscles
Authors: Venable John H. 
Published: February 2005

AbstractCastration of adult male mice produces a true atrophy of their levator ani muscles until the muscle reaches a stable weight within 45 days. Subsequent treatment with testosterone produces a true hypertrophy from the stable neutered state. The weight changes in the muscle are accounted for solely by changes in the size of the muscle fibers. No mitotic activity accompainies atrophy or hypertrophy. The number of cell nuclei and the amount of DNA in the muscle is unaltered.
Correlation of types of cortical grain structure with architectural features of the human skull
Authors: Dempster Wilfrid T. 
Published: February 2005

AbstractSeven grain‐form relationships, as indicated by the split‐line patterns, are recognized in the cortical bone of the adult human skull: (1) random pattern of braincase, (2) planes and (3) ridges with elongated grain, (4) troughs with transverse grain, (5) concavities with circular grain, (6) edges, and (7) spines. Concavities may show superimposed trough or ridge structure, and troughs may be marked by localized ridges and planes. That is, trough patterns are dominant over concavity patterns, and ridge patterns are dominant over both trough and concavity patterns. Finally, there are a few small cranial areas that are random distributions in some skulls and planes in others; the skull vault proper, however, except for the forehead region and internal sagittal markings, has a random pattern throughout.The mechanical significance of the various patterns and the areas on which they are found are discussed and explained on the basis of principles of mechanics and architecture. The form‐texture relationships are discussed as architectural features of the skull, and their adequacy and limitations are analyzed in terms of their reaction to force systems and their proneness to fracture.
A study of mineral density surrounding resorption sites in teeth
Authors: Avery J. K. , Meyers R. A. , Hale L. E. 
Published: February 2005

AbstractAn investigation of mineral density surrounding lacunar resorption sites in cases of both internal and external root resorption, was carried out on 37 human primary and permanent teeth. In addition, equivalent areas of the roots of 14 normal appearing teeth were studied for comparison. Thirty‐two of the teeth were analyzed using microradiographic and microhardness techniques and the remainder were studied microscopically after histologic preparation. The teeth used for microradiographic analysis were embedded in plastic, bisected and half of each tooth was sectioned at 70–100 μ. Microadiographs were taken at 9.5 kv and exposed to 30 milliamperes for 25 to 40 minutes. The other halves of the teeth were used for microhardness tests using a Tukon Microhardness Tester. One series of microhardness measurements was made 10 to 40 μ from sites of active resorption in root dentin and a second series was made 250 to 500 μ from these sites. The hardness measurements of the first series were found to be significantly lower than those of the second in cases of both external and internal resorption. Hardness values of the surface of normal appearing roots were also less than areas 250 to 500 μ deeper in the dentin. Microradiographs did not reveal any definite zone of subsurface demineralization although some resorption sites were bordered by irregular areas of decreased radiodensity which may be due to superimposition of several resorption sites within the thickness of the tooth section. Histologic observations did not reveal a definite subsurface demineralization gradient. The lacunar resorption front was found to be a multilocular and completely interconnected system.
Light and electron microscopic observations on the inner plexiform layer of the rabbit retina
Authors: Raviola Giuseppina , Raviola Elio 
Published: February 2005

AbstractBy comparison of electron micrographs with light microscopical specimens impregnated with the Golgi technique, the large endings of the rod bipolar cells have been identified in the innermost region of the inner plexiform layer of the rabbit retina.The rod bipolar endings contain ribbons and synaptic vesicles, do not synapse with the perikaryon of the ganglion cells, are presynaptic to ganglion cell dendrites and to nerve processes which contain synaptic vesicles but lack ribbons. In these synaptic contacts a ribbon is closely associated with the presynaptic membrane and a dense web of fuzzy material is adherent to the cytoplasmic aspect of the postsynaptic membrane. Commonly, one of these synaptic contacts involves a rod bipolar ending and two postsynaptic processes. The postsynaptic process which is provided with synaptic vesicles is often, in turn, presynaptic to the same rod bipolar ending. This synaptic contact is characterized by the presence of a cluster of vesicles closely related to the presynaptic membrane, whereas the postsynaptic membrane lacks a definite subsynaptic web.In the intermediate and scleral regions of the inner plexiform layer endings containing ribbons and synaptic vesicles show with neighboring nerve processes a synaptic pattern similar to the rod bipolar endings. Nerve processes containing synaptic vesicles but lacking ribbons are presynaptic to the perikaryon and dendrites of the ganglion cells; the synaptic contact shows a cluster of vesicles adherent to the presynaptic membrane. Bipolar cells are proposed as the source of the ribbon containing processes while amacrine cells are proposed as the source of the processes devoid of ribbons and presynaptic to both bipolar endings and ganglion cell dendrites and perikarya.
A light and electron microscopical study of neurofibrils and neurofilaments at neuro‐neuronal junctions in the dorsal lateral geniculate nucleus of the cat
Authors: Guillery R. W. 
Published: February 2005

AbstractNeurofibrillar rings and spheres one‐half to 2 μ in diameter occur throughout the dorsal lateral geniculate nucleus of the cat. Counts confirm that they occur predominantly in laminae A and A1, and only rarely in lamina B and the central interlaminar nucleus. The rings lie in zones of lightly argyrophilic tissue between perikarya and rarely contact cell bodies. The argyrophilic zones are 5–20 μ wide, forming a continuous reticulum throughout laminae A and A1.Electron micrographs show rings and nests of neurofilaments that match the neurofibrillar structures in size and distribution. These filaments are not found in axons, but occur in spheroid dendritic appendages, which have previously been described on Golgi preparations. The appendages lie in synaptic zones which are 5–20 μ wide and encapsulated by glial lamellae. Within the zones two major types of specialized contact are recognizable. “Regular” contacts (axo‐dendritic and axo‐axonal) resemble synaptic contacts in other parts of the CNS. “Filamentous” contacts (axo‐dendritic and dendro‐dendritic) show neurofilaments in the dendritic cytoplasm and show no concentration of vesicles on the axonal side. Within the appendages filaments from adjacent filamentous contacts join to form a nest around a group of mitochondria.Comparison with previous studies suggests that these dendritic appendages, which receive regular and filamentous contacts, form a major receptive site for the retinal afferents.
Fine structural differences in “fast” and “slow” muscle fibers of the crab
Authors: Cohen Melvin J. , Hess Arthur 
Published: February 2005

AbstractThe muscle fibers in the accessory flexor muscle of the crab were examined with the electron microscope. The limiting membrane of the muscle fiber invaginates at many points to form an internal extrafibrillar membranous system between the muscle fibrils. Two types of muscle fiber were found. In one, the fibrils are well separated from each other by an extensive membranous system, the sarcomere lengths are short, and the filaments in the A band are thick. This muscle fiber is the same as the fast fiber previously found physiologically. The other type of muscle fiber has large fibrils poorly separated by a relatively scant system of internal membranes. It has relatively long sarcomeres and comparatively thin filaments in the A band. This type of fiber is the same as the slow fibers described physiologically. Fibers intermediate in type are also found. Nerve terminals with typical synaptic vesicles occur and appear similar on both types of muscle fiber under the electron microscope. Membrane thickenings of nerve ending and muscle fiber also occur at the terminals on both types of muscle fiber. The nerve terminals on the fast fiber are much more easily found and hence more numerous than on the slow fiber. A comparison is made between the invertebrate and vertebrate fast and slow fibers, and some physiological implications of these findings are discussed.
Cell number as a measure of distribution and renewal of epithelial cells in the small intestine of growing and adult rats
Authors: Altmann G. G. , Enesco M. 
Published: February 2005

AbstractBy the use of DNA determinations and cell counts with and without previous colchicine treatment, the absolute numbers of villus epithelial cells, and of dividing and nondividing crypt epithelial cells were determined in ten successive segments of the small intestine of 17‐day (weanling), 37‐day (young) and 87‐day old (adult) male rats.In adults, the number of villus epithelial cells per segment decreased gradually in the duodenoileal direction, while the number of dividing and nondividing crypt epithelial cells remained fairly constant. It was deduced that the turnover time of the villus epithelium gradually decreases, but that of the crypt epithelium remains constant along the small intestine.When the entire small intestine was considered, from weanling to adult age, the relative and absolute numbers of dividing and nondividing crypt epithelial cells increased; the calculated number of epithelial cells produced daily rose from 112 million to 1796 million. Meanwhile, the rate of growth of the intestinal epithelium diminished allowing more and more of the produced cells to participate in renewal: about 25, 885 and 1796 million cells daily in weanling, young and adult rats, respectively. The mean turnover time of the intestinal epithelium decreased from about 22 days in weanling rats to about 2.1 days in adult rats, indicating a tenfold increase in renewal rate.
Observations on the fine structure of spermatozoa of the bush baby (Galago senegalensis), the African green monkey (Cercopithecus aethiops) and man
Authors: Bedford J. M. 
Published: February 2005

AbstractA description is given of some fine structural features of mature spermatozoa from the bush baby (Galago senegalensis), the African green monkey (Cercopithecus aethiops) and man, with additional comments on sperm from the slow loris (Nycticebus coucang) and the crab‐eating macaque (Macaca irus). The arrangement of the sperm organelles in these primates is similar to that demonstrated in the sperm of other mammals, but notable species differences do occur. The bush baby spermatozoon, for instance, displays a complex system of membranes which envelop the neck and anterior midpiece. The human spermatozoon, unlike that of many other mammals, has no subacrosomal space or “perforatorium.” This structure is quite prominent, however, in lorisoid and macaque spermatozoa, and it is shown in the bush baby that its electron‐dense material extends posteriorly from the apex of the head in the space between the inner acrosome and nuclear membranes. In electron microscope preparations of anthropoid spermatozoa, the cell membrane which overlies the acrosome cap only occasionally displays the swollen distorted form seen commonly here in the spermatozoa of prosimiae, and previously in various other mammals.In contrast to the uniform spermatozoa obtained from the lorisoid and macaque monkeys, a significant proportion of spermatozoa in the human samples examined showed many abnormal features including misshapen sperm nuclei, cystic formations in the rostral region of the acrosome cap, and irregular alignment of mitochondria in the neck and midpiece.
Ultrastructural and histochemical analysis of cytoplasmic laminar bodies in lateral geniculate neurons of adult cat
Authors: Doolin Paul F. , Barron Kevin D. , Kwak Sharon 
Published: February 2005

AbstractThe structure of highly organized, cytoplasmic laminar bodies (CLB) of cat lateral geniculate body neurons is described. CLB are derived from endoplasmic reticulum (ER). The occurrence of other cytoplasmic bodies also derived from ER and mesh‐like in composition is noted. Stacks of dense membranous elements, restricted to one pole of each type of cytoplasmic body, were encountered. Mention is made of the relative persistence of CLB in atrophic neurons that show marked changes including loss of cytoplasmic granular ER.The tubules of CLB are normally coextensive with the granular ER. The topographic relationships of CLB with other cellular organelles such as mitochondria, Golgi complex and the nucleus are discussed.Routine staining techniques clearly demonstrate the CLB in 2 μ paraffin sections of tissue fixed by perfusion with buffered formalin. Histochemical tests show that CLB are chemically complex structures containing protein, lipid and polysaccharide components.
A histochemical study of epithelial mucin in the chick chorioallantois
Authors: Conklin James L. 
Published: February 2005

AbstractHistochemical methods demonstrate the accumulation of two types of mucous inclusion in the allantoic epithelial cells of the chick embryo.One type of inclusion contains a sialomucin that is PAS‐reactive, unstained by Alcian blue and other anionophilic dyes and is susceptible to digestion by Vibrio cholerae neuraminidase.The second inclusion contains an apparent sulfomucin which is Alcianophilic at pH 1.0, unstained by anionophilic dyes after a methylation‐demethylation sequence and resistant to testicular hyaluronidase. This sulfomucin exhibits PAS reactivity after desulfation procedures.Both types of mucus occur in individual cells and are normal components of the chorioallantois. Accumulation of the inclusions is enhanced by lowering the pH of the allantoic fluid or as a result of organ transplantation.
Electron and light microscopic observations on relationships between lymphocytes and intestinal epithelium
Authors: Meader Roland D. , Landers Dennis F. 
Published: February 2005

AbstractCorrelated electron and light microscopic studies of the distribution, position, appearance, migration and fate of lymphocytes with relation to the intestinal epithelium of the young adult rat, mouse, hamster and man have been made. Under the conditions of this investigation, the lymphocytes which are normally present in the intestinal epithelium are intercellular in position, irrespective of their level within the epithelium. The great majority of these cells are located in the basal region of the epithelium, below the level of the epithelial cell nuclei. There was no evidence of lymphocytic degeneration. Lymphocytes migrated from the lamina propria into the epithelium and back again into the lamina propria, with no evidence of movement toward the free surface of the intestinal epithelium and extrusion into the lumen.