bluuebunny/crossref_metadata_2025_split huggingface dataset:
A circadian susceptibility rhythm in rats to pentobarbital sodium
Authors: Scheving Lawrence E. , Vedral Donald F. , Pauly John E. 
Published: February 2005

AbstractA colony of adult rats was maintained on a standardized regimen with artifical photoperiods extending from 0600 to 1800 alternating with 12 hours of darkness. Every hour during a 24‐hour period separate subgroups of rats were injected with 35 mg/kg of pentobarbital sodium, and the duration of time each animal remained under anesthesia was recorded.The rats remained anesthetized for longer periods of time between the hours of 1600 and 2200 than at other times of the day; this indicates that the response to the drug is dependent on he circadian phase system of the animal. When the results were plotted along the 24‐hour time scale, the difference between the crest and trough of the curve was about 100%.A second colony of rats was maintained in a similar fashion except that the animals were subjected to continuous illumination. The rhythm of their susceptibility to pentobarbital sodium persisted for at least four weeks in a form highly modified from the animals synchronized to a light‐dark cycle.In a third colony of animals, the rhythm still was present four months after they had been blinded; but it was modified and different from either the light‐dark synchronized animals or from rats subjected to continuous illumination.The importance of recognizing the time structure of the living organism is discussed.
Distribution of the extracellular space during postnatal maturation of rat cerebral cortex
Authors: Bondareff William , Pysh Joseph J. 
Published: February 2005

AbstractThe cerebral cortices of young adult and immature Sprague‐Dawley rats, 10, 14, and 21 days of age, were rapidly frozen in situ and substituted at –78.5°C with a 1% solution of osmium tetroxide in acetone. In random electron micrographs of each animal, each representing 42 μ2 of cerebral cortical molecular layer, the extracellular space was evaluated stereologically.In all cases the extracellular space was found to be distributed as large extracellular lakes of variable dimension. Where no extracellular space was apparent adjacent cell processes were joined by 5‐membered complexes, which appeared to represent fusion of immediately adjacent plasma membranes.In 10‐day old animals an extracellular space of 40.5% was found. This diminished progressively to 31.8% at 14 days and 26.3% at 21 days, which approached the adult value of 21.7%. These data were consonant with measurements of the maturing extracellular space based on uptake studies of tracers, water and electrolyte determinations and impedance measurements. They appear to represent accurately the changing distribution of extracellular water in rapidly maturing cerebral cortex.
Oogenesis and ovarian development in the prenatal pig
Authors: Black J. L. , Erickson B. H. 
Published: February 2005

AbstractGametogenesis and ovarian development were examined by means of histologic, cytologic and radioisotopic techniques in porcine ovaries of ages ranging from 13 days post coitum (PC) to birth (114 days PC). Limited observations were made in postnatal ovaries (birth to 130 days post partum).Primordial germ cells were noted at 18 days PC in the region of the germinal ridge (border of mesonephros) seven days prior to its formation (24–25 days).Meiosis began as early as day 40 in some cases and was a characteristic of most ovaries by day 50.Diplotene, the resting stage of porcine oocytes, first appeared at 50 days PC and 99% of all germ cells were at diplotene by 20 days post partum. Both the paucity of oogonia and absence of oogonial mitoses at day 100 PC signaled the end of oogenesis.The number of germ cells increased dramatically from the 5,000 seen at 20 days PC to a peak of 1,100,000 at 50 days. Subsequently, germinal mitotic activity decreased and necrosis of germ cells concurrently increased, resulting in a population of approximately 500,000 germ cells at birth.The injection of tritiated thymidine into fetuses of varying ages revealed that in the pig the definitive stock of oocytes arises from the prenatal period prior to day 100 with the 70‐day PC‐period being the major contributor.
A light and electron microscopic study of perineuronal glial cells and processes in the rabbit neocortex
Authors: King James S. 
Published: February 2005

AbstractThe morphology of satellite cells was determined by examining brom formalin fixed tissue stained by the silver carbonate technique, and tissue fixed in gluteraldehyde, post‐fixed in osmium and prepared for electron microscopy.Light microscopy indicated that oligodendrocytes and astrocytes were the predominant perineuronal cell types. Cells with intermediate morphological characteristics were also observed. The light microscopic criteria for cellular indentification were the comparative size and shape of the cell bodies, and the number and nature of glial processes.Electron microscopy revealed perineuronal cells with round to oval shaped cell bodies, dense nuclear and cytoplasmic matrices, and a rich compliment of organelles. A second, less numerous, type of satellite cell had a larger, oval, elongate, or somewhat angular cell body, light nuclear and cytoplasmic matrices, and gliofibrils and glycogen. The former correlated well with the light microscopic oligodendrocyte and the latter with the astrocyte. “Dark cells” were not observed in a satellite position with the electron microscope nor were cells observed that conform to Hortega's “spiny microglia” in our silver preparations. Specializations of the plasma membranes of satellite glial cells and neurons were observed, and were interpreted as possible morphological evidence for “transport” between neurons and neuroglia.
The germinal layer of the growing human brain during early fetal life
Authors: Duckett Serge 
Published: February 2005

AbstractThe telencephalic vesicles of the human brain appear during the fifth week of embryonic life. These vesicles are closed containers filled with ventricular fluid until the fifteenth week when it escapes through the newly‐formed foramen of Magendie.The light and electron microscopic studies reported here support the notion that the germinal layer of the telencephalon has an absorptive role between the eighth and fifteenth weeks of fetal life. This assumption is based on the structure and the arrangement of the cells of the germinal layer, which resemble and are arranged in a manner similar to that of other absorptive units such as the renal proximal tubules, the gallbladder and the intestine. The absorbed material is presumably contained in the ventricular fluid.
An electron microscopic study of the relationship between axon diameter and the initiation of myelin production in the peripheral nervous system
Authors: Matthews Murray A. 
Published: February 2005

AbstractMid‐thoracic dorsal and ventral roots from adult rats, cats and cows were prepared for electron microscopy using standard techniques. Axon diameters were measured on photographs of known magnification. Minimal diameters of the unmyelinated fibers in the spinal cords of these animals were measured also. With the exception of a few overlapping diameters unmyelinated fibers were smaller than the smallest myelinated fibers in all the material examined. In the dorsal roots of the cow, the unmyelinated fibers, as a group, were larger than those of the rat and cat, and very few were enclosed by any one Schwann cell. The largest unmyelinated fibers were singly enclosed. In addition, the dorsal root of the cow contains many more small myelinated fibers than those of the other two species. In the ventral roots, a progressive increase in the size and relative numbers of myelinated preganglionic fibers from rat through cat to cow was noted. These facts indicated that myelination is directly dependent on fiber diameter irrespective of age, species or function although less precisely than was indicated by the earlier studies of Duncan ('34). Although the critical diameter for myelination in the peripheral nervous system is about one micron, in the central nervous system it is 0.3 μ or less.
Electron microscopic study of somatotropic and lactotropic pituitary cells of the Syrian hamster
Authors: Dekker Andrew 
Published: February 2005

AbstractSomatotropic (STH) and lactotropic (LTH) cell types of the Syrian hamster's adenohypophysis are readily identified by electron microscopy. Pituitaries of growing and lactating animals were studied to establish the identity of these cell types. The pituitaries of normal, gonadectomized and thyroidectomized adult male and female hamsters were also examined. Distribution of these cell types was determined by examining all blocks of half the gland in adults and of the whole gland in immature animals. Electron microscopic fields were systematically photographed and cell types counted.The STH and LTH cells are distinguished by the size of the secretory granules which measure maximally 300 and 700 mμ, respectively. A marked predominance of STH and LTH cells is present in the intact adult female gland. Approximately equal numbers of STH and LTH cells are seen in the female gland, whereas, there are significantly fewer LTH cells in the male adenohypophysis. The proportion of the gland comprising STH cells, however, appears to be constant in both male and female.Both cell types are distributed throughout the gland with no regional localization.
Stage dependent transfer of systemically injected foreign protein antigen and radiolabel into mouse ovarian follicles
Authors: Glass Laurel E. , Cons Jean M. 
Published: February 2005

AbstractThe appearance of albumin‐like antigen and of radioisotope in mouse ovarian follicles following the systemic injection of 10 mg human serum albumin I131 (HSAI131) was studied by immunohistological and autoradiographic methods.Both isotope and antigen appeared in granulosa cell cytoplasm, ooplasm and oocyte nuclei in similar (or identical) positions. Qualitative impressions from fluorescent antibody preparations were that follicle stages (I, smallest; IX, largest) differed in relative amounts of detectable albumin‐like antigen. In addition, autoradiographic grain counts over 1421 follicles, compared by Sign Test, demonstrated statistically significant stage differences in amount of isotope detected. Radiolabel (and HSA‐like antigen) in ooplasm was highest at Stages I and VII‐IX and lowest at Stage III. Granulosa cell amounts were highest at Stage III and higher than or equal to ooplasm amounts at every other stage (except, perhaps IX). The relative amount of “label,” antigenic or isotopic, in oocyte nuclei was always less than in ooplasm and increase or decrease occurred one stage later than in ooplasm. The relative amount of radiolabel in ovarian blood vessels always exceeded that in granulosa cells and oocytes.The data are consistent with the interpretation that: (a) systemically injected foreign protein was transferred without major degradation from the blood to constituent cells of the mouse ovarian follicle; (b) transfer was stage dependent; (c) transfer occurred both before granulosa cells completely surrounded the oocyte and after oocyte microvilli and granulosa cell processes interdigitated; and, (d) transfer followed a concentration gradient.
Role of melanocyte morphology in pigmentation of mouse hair
Authors: Sweet Stephen E. , Quevedo Walter C. 
Published: February 2005

AbstractThe pigmented hair provides a lasting record of the complex interactions of melanocytes and keratinocytes which lead to its formation within the hair follicle. Large clumps of pigment are deposited within the developing hair when follicular melanocytes are uprooted from fixed sites in the hair bulbs. The frequency with which melanocytes are incorporated is in some way related to their morphology. Melanocytes with poorly developed dendrites (nucleopetal melanocytes) are dislodged from hair bulbs more frequently than those with well developed dendrites (nucleofugal melanocytes). A detailed investigation of pigment clumping brought about by action of the light (Blt) and leaden (ln) genes has yielded results consistent with this interpretation. Leaden melanocytes remain nucleopetal in morphology throughout the hair growth cycle whereas light melanocytes, initially nucleofugal, often become nucleopetal. The unexpected absence of pigment clumping in light (Blt/—) mice which are homozygous or heterozygous for the pink‐eyed dilution gene p, is correlated with the persistence of nucleofugal melanocytes. In contrast, the pigment clumping found in the hairs of pink‐eyed leaden mice is associated with the presence of nucleopetal follicular melanocytes. The differing interactions of the p‐locus with the ln and b loci, suggest that the leaden and light genes elicit similar morphological changes in melanocyte morphology via different developmental pathways.
Frequency and size of muscle fibers in athletic body build
Authors: Etemadi A. A. , Hosseini F. 
Published: February 2005

AbstractIn one prototype athletic subject and two persons of more average body build complete mid‐point cross sections of the biceps brachii muscle were made. All three cross‐sections were photomicrographed on overlaping fields, and composite photomicrographs of the complete muscle cross section were made. An individual fiber count on these photomicrographs was carried out.The number of individual muscle fibers in the athlete and the other two persons amounted to 316,243, 227,233 and 199,240 fibers respectively. Sampling methods were also tried on the sections for the evaluation of different estimation procedures. Fiber size distributions were arrayed in frequency polygons in each case. Six thousand fibers, randomly chosen from different parts of the section were measured in each case by means of an automatic counter. The mean fiber diameters are 42.26 ± 7.616 μ in the athletic subject and 24.1 ± 4.583 μ and 22.54 ± 4.919μ in the other two subjects.
The fine structure of the human peridental ligament
Authors: Bevelander Gerrit , Nakahara Hiroshi 
Published: February 2005

AbstractAn electron microscope study was made of the human peridental ligament of the young adult. Examination of several cells which occur in this site exhibit a marked variation in number and distribution of organelles. The fibrous components made up chiefly, if not entirely, of collagen fibers averaged 600 Å in diameter. These fibers usually referred to as principal fibers show an arrangement both in the peridental space proper and also at the surface of the root of a marked irregularity, more so than can be ascertained at the optical level. Our study shows that the arrangement of the principal fibers is more complex than previously described and further that many of the diverse cells present in the peridental space are in an active functional state indicative of the dynamic potential they possess in reference to fibrilogenesis, cementogenesis and osteogenesis in this area.
The ultrastructure of the parathyroid glands of young cats
Authors: Capen Charles C. , Rowland George N. 
Published: February 2005

AbstractThe fine structure of the parathyroid glands of normal rapidly growing cats (9–22 weeks of age) was described and compared with the findings reported in other species. The predominating active chief cells were relatively electron‐dense and contained well developed organelles and frequent secretory granules. Inactive chief cells were slightly larger and had a more electron‐transparent cytoplasm. Cytoplasmic organelles were less well developed and secretory granules were less frequent than in the active chief cells. Oxyphil cells or transitional forms were not identified in the parathyroid glands of kittens. Occasional cilia were observed in chief cells. They arose near centrioles and protruded from the plasma membrane into the intercellular space.
Ultrastructural changes in liver parenchymal cells of the mouse following postnatal cholecystectomy
Authors: Yamada Kazuyori 
Published: February 2005

AbstractUltrastructural changes have been induced in liver parenchymal cells of the mouse by postnatal cholecystectomy. The major changes included frequent occurrence of numerous vesicles, frequent development of extensive forms of copious Golgi apparatus and an increase in number of lysosomes and microbodies in the peribiliary cytoplasm, and dilatation of bile canaliculi. The cytoplasm beyond the peribiliary zone, contained numerous large mitochondria which were often associated with abundant granular endoplasmic reticulum. In view of the known cytophysiological roles played by the cytoplasmic components undergoing such changes, an elevated activity of bile secretion is suggested in the liver cells of cholecystectomized animals. The presumed high activity of bile secretion in the cells can be comprehended in terms of a compensatory adaptation to the loss of bile concentrating capability of the biliary system due to the removal of the gallbladder.
Chloride movements during perfusion fixation with glutaraldehyde
Authors: Van Harreveld A. , Khattab F. I. 
Published: February 2005

AbstractThe cerebral and cerebellar cortices of mice were subjected to a histochemical method for the demonstration of chloride after perfusion fixation with glutaraldehyde. Unfixed, nonasphyxiated cortices subjected to the same chloride method were used as controls. Sections of control material showed a rather uniform chloride distribution in which only the pia and the blood vessels stood out as dark structures containing an appreciable amount of chloride. Sections of glutaraldehyde fixed cerebral cortex showed an accumulation of chloride in apical dendrites. In glutaraldehyde fixed cerebellar cortex the chloride accumulated in the fibers of Bergmann and sometimes in the large dendrites of Purkinje cells. The chloride movement during glutaraldehyde perfusion is in all respects comparable with the movement of chloride caused by asphyxiation of the cerebral and cerebellar cortex.
Alterations in blood vessels in X‐irradiated spinal cords of young rats
Authors: Gilmore Shirley Ann 
Published: February 2005

AbstractAdministration of x‐rays (4000 r) to lumbar spinal cords of three‐day‐old rats caused a loss of neuroglia with an inhibition of myelinogenesis, neuronal damage and necrosis. In contrast, the loss of neuroglia following administration of 2000 r is temporary, with myelinogenesis occurring later than normal. Preliminary observations suggested that differences in vascular responses to these two amounts of x‐rays might account for these differing fates of the spinal cords; therefore, this investigation was designed to study further the reactions of the intramedullary vessels.Rats, irradiated when three days of age, were killed 1 to 27 days later. Some were killed by perfusion with Monolite Fast Blue BNVSA Paste, a substance retained in the vessels and readily visualized on microscopic examination. The remaining rats were decapitated, and spinal cords were stained by Gomori's method for alkaline phosphatase. The earliest consistent alteration, a decreased number of vessels, was noted seven days following irradiation with either dose. Rats receiving 4000 r had marked losses of blood vessels, vasodilatation and necrosis by 15 days post‐irradiation; whereas, a decreased number of vessels was the only change noted in rats irradiated with 2000 r. Alterations in rats receiving 4000 r remained the same or became more severe throughout the study; spinal cords in rats receiving 2000 r returned to normal. These vascular alterations correlate well with the changes in other spinal cord components described previously by this investigator.
A correlative investigation of the human rectovaginal septum
Authors: Milley Paul S. , Nichols David H. 
Published: February 2005

AbstractAnatomists and gynecologists have debated the existence of a rectovaginal septum in the human female. In this investigation the connective tissue between the vagina and rectum has been reexamined by both dissection and light microscopy in four specimen types. Specimens studied and compared totaled 143 and represent an age range of from eight fetal weeks to 100 years. Included were specimens from patients with different degrees of parity and both normal and abnormal pelvic visceral support.It has been shown that a definite rectovaginal septum exists in the human female and it is probably the homologue of the male rectovesical septum. The septum is well formed by the fourteenth fetal week and consists of a thin vertical sheet of dense connective tissue which is translucent in the fresh state. In the coronal plane the septum parallels the sacral curvature. It also curves posterolaterally to become fused with the parietal endopelvic fascia. The septum extends inferiorly from the rectouterine peritoneal pouch to the perineal body. It is usually adherent to the posterior aspect of the vaginal connective tissue, capsule. This adherence, together with the difficulty in identifying it histologically may explain why the existence of the rectovaginal septum has been denied.
Distribution and weights of various cell types in the rat stomach
Authors: McCabe Donald R. , Kent Thomas H. , Hogben C. Adrian M. 
Published: February 2005

AbstractA line sampling method was used to determine the relative volumes of various cell types in the mucosa of the body of the rat stomach. The technique was simple to perform, reproducible and independent of many variables inherent in previous cell counting techniques. Weights of the various cell types were calculated from stomach weights, relative mucosal volumes and cell concentrations in the mucosa. In the five animals studied, gastric body mucosa average 40% of the stomach weight and 1.8 gm per kg of rat. Parietal cells averaged 40% of the gastric body mucosa weight and 0.7 gm per kg of rat. There was no significant variation in parietal cell concentration throughout the gastric body mucosa of the rat. Chief cells averaged 18% of the gastric body mucosa and 0.3 gm per kg of rat. Up to three‐fold variations in chief cell concentration occurred with highest concentrations near the greater curvature and in proximal areas of the body mucosa. Mucous surface cells, mucous neck cells, and connective tissue made up 22, 9, and 7% of the body mucosa respectively and showed only minor varitions in concentration.
Fine structure of neuromuscular relationships in mouse heart
Authors: Thaemert J. C. 
Published: February 2005

AbstractHearts of mice were fixed in osmium tetroxide, embedded in Epon, sectioned for electron miscroscopy and stained with uranyl acetate. Various regions of these hearts were examined for neuromuscular relationships. Unmyelinated nerve bundles with partial Schwann cell investment, frequently are present within the perivascular spaces of capillaries and arterioles in the myocardium of all regions studied. Neuromuscular junctions are located in the myocardium of the right atrium, the inter‐ventricular septum and the outer ventricular walls. Neuromuscular junctions seem to be absent from the myocardium of the apex. Previously reported neuro‐effector relationships within various tissues are discussed in relation to the findings of this study.
Structure and evolutionary implications of the musculi arrectores pilorum in chiroptera
Authors: Quay W. B. 
Published: February 2005

AbstractSkin samples from 16 genera and 19 species of bats were studied histologically. These and review of the literature revealed musculi arrectores pilorum composed of smooth muscle present only in Megachiroptera and complex cutaneous striated muscle systems best developed in Microchiroptera. Smooth muscle arrectores of the mid‐dorsal neck skin of Hypsignathus monstrosus are described in detail and resemble those of generalized structure in other mammalian Orders. Shoulder pouches of the epaulet bats (Epomophorus and Epomops) contain compound smooth and striated muscle systems for eversion of hair tufts and pouch respectively. An evolutionary trend within the Chiroptera of reduction in smooth muscle arrectores and replacement by integumentary striated muscle fibers is suggested.