bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epidermal growth factor in the submandibular glands of inbred mice
Authors: Tom‐Moy May , Barka Tibor 
Published: February 2005

AbstractEpidermal growth factor (EGF), an androgen‐dependent polypeptide, occurs in high concentration in male mouse submandibular gland. Glands of adult male and female mice of six inbred strains (129/J, C57BL/6J, C58/J, SWR/J, RF/J, A/J) were assayed for EGF by radioimmunoassay. In all strains, the glands of males contained 30 to 500‐fold more EGF than those of females. Furthermore, significant differences in EGF content were found among the various strains in both sexes; the highest amount of EGF was present in RF/J and the lowest in C57BL/6J, with a ratio of three in the males and four in the females of the two strains, respectively.Factors that effect EGF levels were analyzed further, using these two strains. EGF was measurable in the glands of mice of both strains at 21 days of age and increased rapidly thereafter, up to 14 weeks of age. Throughout postnatal development, the level of EGF was greater in the glands of RF/J mice than in those of the C57BL/6J animals. Thirty days after castration, the EGF levels were reduced by about 98% in both strains, but the strain difference was not abolished. Testosterone implants (1 mg in Silastic tube) in castrated mice induced EGF levels six‐ to ten‐fold compared to castrates. Even in induced animals, which had similar plasma testosterone levels, as measured by radioimmunoassays, the difference in EGF levels between the two strains was manifest. Such a difference, however, was not seen after the daily administration of 5‐alpha‐dihydrotestosterone for 3–14 days. Immunocytochemical staining for EGF also indicated a higher concentration of the polypeptide in the glands of RF/J mice than in those of C57BL/6J animals, and confirmed the exclusive localization of EGF in the cells of the granular convoluted tubules (GCT). According to our morphometric analysis, in the glands of male RF/J mice the GCT compartment occupied a greater portion (8% greater, P<0.001) of the gland volume than in C57BL/6J mice. The difference in the relative GCT volumes in the glands of female mice of the two strains was, however, statistically not significant. There was no direct correlation between the amount of EGF and the relative volume of the GCTs in the two strains. The evidence obtained implies that strain differences in submandibular‐gland EGF levels are determined genetically.
Effects of Ca+2 and Mg+2 deprivation on cell shape in cultured ovarian granulosa cells
Authors: Batten Bruce E. , Anderson Everett 
Published: February 2005

AbstractAfter 3 days in culture, rat ovarian granulosa cells assume a flattened epitheloid organization. Ca+2 and Mg+2 deprivation results in cellular rounding which is reversible and was monitored by phase‐contrast time‐lapse cinematography. Concomitant with the shape change is a dispersion of the structural proteins actin and α‐actinin. The arrays of large actin‐containing bundles (stress fibers) are converted to a diffuse network as observed by electron microscopy. Alpha‐actinin, which was observed by immunocytochemistry to be in a periodic array along the actin bundles, is disrupted also and redistributed in the periphery of the cell upon rounding. Measurements made of the culture medium during the rounding process indicate that there is a loss of Ca+2 and Mg+2 from the cell interior. These data led us to speculate that Ca+2 and/or Mg+2 are necessary in order to maintain the integrity of stress fibers and/or restrict the movement of α‐actinin anchoring sites within the membrane.
Vascular pathways in nonsinusal red pulp—an electron microscope study of the cat spleen
Authors: Blue Julia , Weiss Leon 
Published: February 2005

AbstractThe red pulp of the cat spleen, including terminal segments of arterial capillaries, pulp venules, and the reticular meshwork, was studied by transmission electron microscopy. Splenic congestion and contraction were produced by barbiturate anesthetic and norepinephrine.Terminal segments of arterial capillaries were ampullary and flared. Blood escaped into surrounding pulp spaces through interendothelial gaps. Pulp venules originated as open‐ended vessels in the reticular meshwork near trabeculae and drained into trabecular veins. Venule walls were thin and composed of squamous endothelial cells, a continuous basement membrane, and reticular cells. Venules in congested spleens had many mural apertures, but venules in contracted spleens had few. The interstices of the reticular meshwork in congested spleens contained large amounts of blood, which often was concentrated, many macrophages, lymphocytes, and plasma cells. Fewer blood cells and scant plasma were present in contracted spleens.The vascular arrangements are anatomically open. Blood takes pathways through the reticular meshwork from arterial terminations to pulp venules. Some pathways through the reticular meshwork probably function as closed vascular channels conveying rapidly flowing blood. Other pathways are functionally open and probably contain slowly moving blood that constitutes a reservoir of red cells.Macrophages formed associations with mature red cells and with reticulocytes. Mature red cells were attached to macrophages in a manner indicating erythrophagocytosis. Reticulocyte attachment had a different appearance and likely resulted in reticulocyte sequestration. Platelets bore pseudopodia which would impede their passage through irregular and cell‐filled pulp spaces. The change in platelet shape probably is responsible for the formation of the splenic pool of platelets.
Species variation in the structure and function of the marginal zone—an electron microscope study of cat spleen
Authors: Blue Julia , Weiss Leon 
Published: February 2005

AbstractThe marginal zone in the cat spleen consisted of a characteristic mixture of lymphocytes and other blood cells located mainly between the several layers of circumferential reticulum around white pulp. A region of fine‐meshed reticulum between white pulp and red pulp, as present in some species, was absent from the cat spleen. Arterial capillaries to the marginal zone were few. Some were continuations of white pulp capillaries, whereas others were red pulp capillaries that likely were continuations of axial capillaries of periarterial macrophage sheaths (PAMS) (ellipsoids). Blood cells deposited in the marginal zone could reach red pulp by passing through the numerous openings in each layer of circumferential reticulum. Lymphocytes appeared to migrate across the marginal zone both toward and away from white pulp. Macrophages lying on the circumferential reticulum of the marginal zone phagocytized cells but did not ingest Thorotrast, although it coated their surfaces. Because of the scarcity of arterial endings and the lack of a macrophage‐charged reticular meshwork, the marginal zone in cat spleen is not a major site of blood clearance and phagocytosis. These functions are better served in PAMS and red pulp.
The effect of insulin‐glucose on microappendages of the plasmalemma in the early chick embryo
Authors: Highison Gregory J. , Low Frank N. 
Published: February 2005

AbstractChick embryos incubated for 18–24 hours (stages 4–6) were immersed for 3–5 minutes in Hanks' Balanced Salt Solution containing either insulin (10−9 M) or D‐glucose (10−1 M) or a mixture of both. The ventral and dorsal surfaces of the entoderm and the ventral aspect of the mesoblast were examined in a scanning electron microscope. D‐glucose alone or insulin alone produced negligible change. When combined these ingredients generated highly pleomorphic microappendages of the plasmalemma. The ventral surface of the entoderm was characterized by a larger number of microvilli, both long and short. Concentrations of microvilli and blebs appeared in recesses at cell margins. Some of these represented mesoblastic protrusions through intercellular apertures in the entoderm. The dorsal entrodermal surface developed stellate clusters of microvilli and blebs. The ventral aspect of the mesoblast became the most pleomorphic area of all. It possessed a variety of microappendages including large populations of microvilli and blebs that resembled the protrusions observed from the subblastodermic cavity. There were also stellate clusters similar to those on the dorsal entodermal surface. The same mesoblastic area in controls was virtually free of microappendages. The mesoblastic protrusions, occuring as they do prior to an established circulation, are interpreted as a “feeding” phenomenon.
Differentiation of the blastocyst of the rhesus monkey
Authors: Enders Allen C. , Schlafke Sandra 
Published: February 2005

AbstractA method of flushing the oviduct and/or uterus of rhesus monkeys was used to obtain a number of preimplantation stages, of which four cleavage stages and seven blastocysts that were judged to be normal were studied cytologically using transmission electron microscopy. In addition to the usual changes in mitochondria and endoplasmic reticulum that accompany differentiation of the blastomeres, the blastocysts with zonae showed sequestration of areas of cytoplasm. The first indications of junctional complexes were short stretches of parallel membrane with a slightly increased density found in the morula stage. Blastocysts developed typical apical junctional complexes, but in addition showed extensive gap junctions linking trophoblast and inner cell mass, and epiblast and differentiating endoderm. Endodermal differentiation occurred at about the same time that a basal lamina was found under mural trophoblast and epiblast (but not polar trophoblast or endoderm). Enlarged torn zonae were found in association with one blastocyst and unaccompanied by blastocysts, including a case in which the animal subsequently proved to be pregnant. This observation suggests that hatching is a normal feature of zonal escape in this species. The trophoblast of blastocysts without zonae had well‐formed apical absorptive areas and, in some instances, long irregular microvilli in the area near the inner cell mass. Cell debris, vacuoles containing debris and isolated cells, although variable, were common features of the preimplantation stage in the rhesus monkey.
Freeze‐fracture studies on the thin limbs of Henle's loop in Psammomys obesus
Authors: Kriz Wilhelm , Schiller August , Taugner Roland 
Published: February 2005

AbstractThe thin limbs of short and long loops of Henle of the desert rodent Psammomys obesus were studied by freeze‐fracture techniques. Intercellular junctions and internal membrane characteristics of thin‐limb epithelia are of interest with regard to the high urine‐concentrating capacity of this animal.The epithelium of the descending thin limbs of short loops is remarkably undifferentiated and equipped with multistrand tight junctions. In the descending thin limb of long loops, two segments are to be distinguished. The upper parts are characterized by an extensive cellular interdigitation and single‐strand tight junctions. Thus, the paracellular pathways are prominent from two aspects: the junctional belt is elongated by interdigitation, and its apico‐basal depth is shallow. The transition from the upper to the lower part appears to be abrupt, as indicated by the change in intramembrane particle density. The lower parts are characterized by a noninterdigitating epithelium with junctions consisting of few, but always more than two, strands. In addition, this thin‐limb segment is characterized by regularly distributed infoldings of the basal cell membrane. The ascending thin limbs are established by an interdigitating epithelium, with junctions generally consisting of one strand. Once again, the elongated junctional belt is shallow.This study presents further evidence that remarkable species differences occur among thin‐limb epithelia, especially concerning the descending thin limbs of long loops. Those differences may well explain discrepant functional findings concerning the transport properties of this segment in various species.
Control of the secretory cell cycle in cat oviduct by estradiol and progesterone
Authors: Bareither Mary L. , Verhage Harold G. 
Published: February 2005

AbstractThe control of the secretory cell cycle by estradiol and progesterone in the oviduct of the cat was studied using light and electron microscopy. The epithelium in ovariectomized animals was cuboidal with no evidence of secretory activity. Estradiol treatment induced hypertrophy, hyperplasia, and the differentiation of both secretory and ciliated cells. Differentiation of the secretory cell included the development of an extensive area of basal rough endoplasmic reticulum and a large supranuclear Golgi region. Apical secretory granules were already present after 3 days of estradiol treatment, and after 4 to 5 days maximum hypertrophy and differentiation had occurred. Most cells contained several apical electron‐dense granules; however, no large accumulation of granules in any one cell was ever observed. Occasional release of secretory product by exocytosis occurred during chronic treatment with estradiol. Rapid elevation of the serum levels of estradiol or progesterone by means of IV injection did not enhance exocytosis or result in any ultrastructural alterations. The chronic administration of progesterone to estradiol‐primed animals resulted in rapid cell atrophy, dedifferentiation, and death (apoptosis) within the epithelium of the oviduct. Secretory granules were no longer observed after 2 days of estradiol and progesterone treatment, and after 7 days the epithelium was approximately the same height as that measured in ovariectomized animals. These data illustrate that estradiol induces the differentiation and maintains the mature state of the secretory cell within the oviductal epithelium of the cat, and that progesterone has an immediate antiestrogenic effect on these cells. This study also suggests that the secretory product is released gradually, as the granules form and mature during chronic estradiol administration.
Circadian organization of thirteen liver and six brain enzymes of the mouse
Authors: North Chester , Feuers R. J. , Scheving L. E. , Pauly J. E. , Tsai T. H. , Casciano D. A. 
Published: February 2005

AbstractThe activities of 13 liver and 6 brain enzymes were studied in 7–12 week old CD2F1 male mice that had been fed ad libitum and standardized either to 12 hours of light (0600–1800) alternating with 12 hours of darkness (1800–0600) (LD 12:12), or to a reversed light‐dark cycle (darkness 0600–1800; light 1800–0600) (DL 12:12). Three separate studies were performed on two different days; in each experiment, subgroups of 14 animals were sacrificed at 3‐hour intervals. Livers were assayed for: isocitrate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase, glutathione reductase, glyoxylate reductase, L‐alanine aminotransferase, glutamate oxalacetate transaminase, pyruvate decarboxylase, fructose‐1‐phosphate aldolase, fructose diphosphate aldolase, fructose 1,6‐diphosphatase, and fatty acid synthetase. Brains were assayed for phosphoglucose isomerase, adenosine triphosphatase, creatine phosphokinase, pyruvate kinase, adenylate kinase, and malate dehydrogenase.All 19 enzymes demonstrated a prominent circadian rhythm in at least one experiment. Moreover, each rhythmic variable showed a statistically significant fit to a 24‐hour cosine(sine) curve by the method of least squares. In general, peak activities of the liver enzymes analyzed were associated with the beginning of the dark cycle and initiation of the animal's activity, while the group of brain enzymes had peak activities which occurred at the beginning of the animals' rest span and were near the beginning of the light cycle. The phasing of each of the rhythms could be reversed within a two‐week span after reversing the environmental light‐dark cycle 180°.
Further observations on the Sertoli cell junctions of the mouse testis after metal contact freeze‐fracture, and comparisons with cellular junctions of other epithelial cells
Authors: Nagano Toshio , Toyama Yoshiro , Suzuki Fumie 
Published: February 2005

AbstractUsing a metal contact freezing method, the junctional complexes of Sertoli cells and other epithelial cells (intestine, liver, and epididymis) in the mouse were studied by freeze‐fracture in unfixed and in aldehyde‐fixed specimens. The tight junctions of the Sertoli cells without fixation consist of discrete rows of particles located preferentially on the E face. Continuous furrows with or without tight‐junctional particles are found on both fractured faces. The majority of the tight‐junctional particles of the Sertoli cells are situated at one side of the furrow rather than in the center. The “aisle” configuration of the gap junction is seen in developing Sertoli cells prepared without fixation. Tight junctions of epithelial cells other than Sertoli cells consist of discrete rows of particles on the E face and furrows on the P face when prepared without fixation. The tight and gap junctions of the Sertoli cells are not affected by fixation, but the tight junctions of other types of epithelial cells are affected as previously suggested. A distribution pattern of the gap‐junctional particles of the Sertoli cells and of other cells shows a pleomorphism. Changes in gap junctions produced by fixation could not be detected clearly. Characteristics of the Sertoli‐cell junctions are discussed. Desmosomes between the intestinal epithelial cells without fixation are presented.
Distribution of fiber types in locomotory muscles of dogs
Authors: Armstrong R. B. , Saubert C. W. , Seeherman H. J. , Taylor C. R. 
Published: February 2005

AbstractThe distribution of Type I and Type II fibers, as determined from histochemical estimation of myofibrillar ATPase activity, was studied within and among the locomotory muscles of the forelimb, trunk, and hindlimb of three mongrel dogs. All Type II fibers had high oxidative capacities as estimated from the histochemical assay for reduced nicotinamide adenine dinucleotide tetrazolium reductase, so they were not further divided into subpopulations. Furthermore, Type I and Type II fibers had similar oxidative potentials as indicated by both histochemistry and biochemistry.Type I fiber populations ranged between 14% and 100% in the muscles sampled. The highest percentages of Type I fibers were found in deep muscles of physiological extensor groups in the arm and thigh that serve to resist gravity (antigravity muscles) when the dog is in the quadrupedal standing position. More superficial muscles in these same groups had fewer Type I fibers. The patterns of Type I fiber distribution among muscles in the antigravity groups of the forearm and leg were the opposite of those in the arm and thigh, with the more superficial muscles of the distal limb segments having more Type I fibers than the deeper muscles. In all limb segments, muscle groups that do not serve to resist gravity did not show as much intermuscular variation. Type I fiber populations in these muscles did not exceed 50%. A stratification of fiber types also existed within muscles, both in extensor and flexor groups, with the deeper portions of the muscles having more Type I fibers than the more superficial portions.
Advanced pulmonary development in newborn guinea pigs (Cavia porcellus)
Authors: Lechner Andrew J. , Banchero Natalio 
Published: February 2005

AbstractMorphological and morphometric evidence is presented to support the hypothesis that lung growth is advanced in mammals born at a relatively mature stage. The lungs from fetal and postnatal guinea pigs ranging in age from gestational age 56 days (normal gestation is 68 days in this species) through 16 days postpartum were fixed in situ by intratracheal glutaraldehyde. Morphometry included measurements of lung volume (VL), tissue and air‐space volumes, fraction of respiratory parenchyma, alveolar (SA) and capillary (SC) surface areas, and the arithmetic mean thickness of the tissue barrier (\documentclass{article}\pagestyle{empty}\begin{document}$ \bar \tau _t $\end{document}). VL, SA, and SC all increased monoexponentially versus body weight (W) from birth to adulthood; the lungs appeared to be in the equilibrated growth phase, with no postnatal period of pronounced tissue proliferation as reported in the newborn rat and mouse. The prepartum value for \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \tau _t $\end{document} was 1.96 μm; this value decreased by parturition to 1.27 μm and did not change significantly with additional age.At the light‐microscopic level, respiratory bronchioles could be visualized giving rise to alveolar ducts by a gestational age of 58 days (10 days preterm) with welldeveloped alveolar septal partitioning evident. Structures resembling the primitive pre‐alveolar saccules of newborn rats were never seen in even the youngest fetal animals. Elastin fibers were also evident at this age, both in bronchiolar and duct walls, as well as in alveolar septa. Using electron microscopy, the airblood barrier appeared mature by a gestational age of 61 days and thereafter, double capillary layers were only rarely seen in septal walls.
Effects of guanethidine‐induced sympathectomy on morphology of the pre‐ and postclosure lleum of the neonatal rat
Authors: McKenzie James C. , Klein Robert M. 
Published: February 2005

AbstractThe disappearance of the characteristic supranuclear vacuole and extensive apical canalicular system from enterocytes of the ileal villi occurs during the third postnatal week in rats. This phenomenon is associated with loss of permeability of these cells to macromolecules and is therefore termed closure. The present study was designed to analyze the influence of neonatal guanethidine (GTN)‐induced sympathectomy on the morphology of the pre‐ and postclosure ileum of the rat. Light and electron microscopy of control and GTN‐sympathectomized rats demonstrated the retention of immature, vacuolated cells on ileal villi as late as 23 days postnatally in GTN‐treated rats. Villi from control rats contained only adultlike nonpermeable cells. Electron microscopy further demonstrated no structural differences in the apical canalicular system or storage vacuoles of the delayed cells in GTN rats when compared to the ileal epithelium from preclosure time periods (7 and 15 days) in both GTN‐sympathectomized and control rats. Goblet cells were counted on Periodic‐Acid‐Schiff‐stained sections of ileum from 7, 15, and 23‐day GTN and control rats. The percentage of goblet cells in the total epithelial cell population of the villus was significantly higher in control versus GTN rats at all time periods. The percentage of goblet cells increased in both groups from day 7 to 15. However, closure in the control group (approximately day 18) was coincident with a steep increase in the percentage of ileal goblet cells which was not evident in the goblet‐cell population of the GTN villus. This pattern of change in control versus GTN goblet‐cell production was correlated with a similar pattern of variation in the number of crypt cell mitoses between the two groups over the same time period.