bluuebunny/crossref_metadata_2025_split huggingface dataset:
The distribution and mobility of anionic sites on the brush border of intestinal absorptive cells
Authors: Jersild Ralph A. , Crawford R. W. 
Published: February 2005

AbstractThe distribution and behavior of anionic sites on the micro‐villous surface of rat jejunal absorptive cells were studied using the multivalent ligand polycationic ferritin (PCF) as a visual probe. Segments were incubated in PCF either before or after glutaraldehyde fixation. The results indicated that the anionic sites can be divided into three groups based on their interaction with PCF: (1) Some sites along the length of the microvilli are accessible for binding PCF in living, unfixed cells. These sites are capable of translational mobility at the membrane surface and can be induced to cluster into discrete patches by PCF. Under appropriate conditions, they may be taken into the cell by endocytosis. Their redistribution is prevented by prefixation, and slowed by incubation at temperatures of 0°C or below. (2) Some sites along the length of the microvilli are inaccessible to PCF without prior fixation. These sites may provide uniform coverage or may be preferentially localized to the distal microvillus. (3) Some sites restricted to the microvillous tips are accessible to PCF without fixation, but are apparently immobile. Their high density on some tips forms a distinctive cap of ferritin particles. More anionic sites were found on the microvilli of the more mature cells of the upper villus. In addition, independent variation was observed in the number of sites in each of the three groups among neighboring cells, irrespective of villous position, suggestive of variations in the turnover of these sites.
Effects of steroids and gonadotropins on follicular development in the hypophysectomized hamster
Authors: Chiras Daniel D. , Greenwald Gilbert S. 
Published: February 2005

AbstractTo determine the rate of follicular development in long‐term hypophysectomized (H) hamsters, single IP injections of 3H‐thymidine were given six days after H and autoradiographs were prepared from animals killed on days 6–15. Only follicles in stages 1 (2–3 layers of granulosa cells), 2 (4–5 layers) and 3 (6–7 layers) were present and there were fewer follicles than in intact, cyclic hamsters. The entire population of follicles in stages 1 and 2 was replaced every five to six days in hypophysectomized hamsters, whereas in cyclic hamsters, complete turnover takes eight days (Chiras and Greenwald, '77).Other groups of H hamsters were treated on days 4–6 with either estradiol benzoate (EB — 10 μg), progesterone (P — 1 mg) or EB and P and then given 3H‐thymidine at 0900 hours of day 6 and killed one hour later. Steroid treatment affected early stages of follicular development: EB stimulated growth of these follicles; P alone had little effect; given with EB, P acted as an antagonist.Other H hamsters were treated with FSH (100 μg), LH (10 μg), FSH + LH, PMS (30 IU) or saline vehicle at 0900 hours six days post‐hypophysectomy. They were injected with 3H‐thymidine at 2100 hours on day 6 and killed one hour later. LH‐ and saline‐treated animals had approximately the same number of follicles; however, there were no stage‐3 follicles in the LH‐treated group and the percentage of labelled follicles in stages 1 and 2 was significantly lower after LH treatment. FSH enhanced follicular development and thymidine uptake. Twice as many stage‐3 follicles were seen in FSH‐treated animals as controls; stage‐4 follicles (>8 layers of granulosa cells) were also encountered after FSH treatment. Labelling Index (LI) and Intensity (L. Int.) for the FSH‐treated group were the highest of all treatments. LH antagonized some of the effects of FSH. PMS resulted in follicular growth similar to that achieved by FSH; however, PMS markedly depressed LI and L. Int., which was probably due to the LH‐like component of PMS. These results demonstrate that the gonadotropins affect the development of small follicles. FSH stimulates growth; LH depresses follicular growth when administered alone and antagonizes some of the effects of FSH.Hamsters pretreated with EB or P on days 4–6 and then given a single, subcutaneous (SC) injection of FSH at 0900 hours on day 6, were treated with 3H‐thymidine at 2100 hours on day 6 to assess the interaction of steroids and FSH. EB pretreatment caused the development of stage‐5 follicles (early antral follicles) but did not increase thymidine uptake (measured by LI and L. Int.) in the small follicles above that attained by FSH alone. P pretreatment diminished thymidine uptake in small follicles, but did not reduce their number.These results demonstrate that in the hamster the population of small follicles, i.e., the often misnamed “pituitary‐independent” follicles, can be influenced quantitatively and qualitatively by steroids and gonadotropins.
Dendritic atrophy in the dentate gyrus of the senescent rat
Authors: Geinisman Yuri , Bondareff William , Dodge John T. 
Published: February 2005

AbstractQuantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number, volume fraction and surface area of dendritic shaft profiles are significantly decreased in senescent rats, relative to young adults. These modifications of dendritic morphology, which are not associated with age‐related changes in dimensions of the molecular layer or in numbers of granule cells, may result from a decrease in the number and/or length of dendrites. In either case, the decreases in the number, volume fraction and surface area of dendritic shaft profiles found in the dentate gyrus of senescent rats signify an age‐related atrophy of dendrites. Comparison of changes in the number and volume fraction of dendritic shaft profiles has demonstrated that age‐related dendritic atrophy involves predominantly smaller dendritic branches.
Synthesis and secretion of glycoprotein in rat bulbo‐urethral (Cowper's) glands. II. Modes of mucus secretion after stimulation by copulation
Authors: Geuze J. J. , Slot J. W. 
Published: February 2005

AbstractCopulation forced the mucous cells of rat bulbo‐urethral (Cowper's) glands to accelerate their secretion. Determination of macromolecularly‐bound hexose as a measure for the mucous contents of the glands and light and electron microscopic observations showed that the glands lost their mucus within four hours after the start of copulation. Secretion of the mucous granules occurred in an exocytotic fashion. This led to the formation of extensive secretory canaliculi extending to the cell bases. Successive mutual coalescing of the mucous granules formed intracellular secretion channels running from the secretory cell surfaces deeply into the cells.The vast reduction of cellular volume by loss of the numerous secretory granules and the sudden addition of large amounts of granule membrane to the cell membrane caused a considerable enlargement of the cell surface. The superfluous cell membrane was stored temporarily in tufts of long microvilli. The appearance of endocytotic structures and lysosomes was interpreted as indicative of internalization and breakdown of cell membrane. Between four and six hours after copulation cytoplasmic volume and size of RER and Golgi complex increased considerably, concurrently with increasing glycoprotein synthesis (Geuze and Slot, '76). During repopulation of the cells with mucous granules, luminal vesicles appeared close to the cell membrane between exocytotic pits. We suggest that the luminal vesicles originate by pinching off from microvilli and apical rims of cytoplasm overlying the mucous granules. Refilling of the glands was slow and took more than one week.
Dispersion of cisternae of rough endoplasmic reticulum in aging CNS neurons: A strictly linear trend
Authors: Hinds James W. , McNelly Nancy A. 
Published: February 2005

AbstractDispersion of cisternae of rough endoplasmic reticulum (RER) in aging rats has been determined quantitatively for mitral cells of the olfactory bulb and Purkinje cells of the cerebellum using a recently published morphometric technique (Cruz Orive, '76). In both cell types dispersion of cisternae occurred throughout the period studied and in a linear fashion. The observed RER dispersion cannot be attributed to a decrease in the total amount of RER, since the total amount of RER was constant in Purkinje cells and increased in mitral cells during the ages studied.
Structural differences of pale and strongly stained motor end‐plates of the rat diaphragm
Authors: Wong Y. C. , Ip M. C. 
Published: February 2005

AbstractAccording to the staining intensities for AChE, the motor end‐plates of the rat diaphragm can be classified into strong (S) and pale (P) types. About 34% of the total end‐plates of the rat diaphragm are of S type and 50% of P type. The P end‐plates differ from S end‐plates in two aspects. First, the secondary subneural clefts of the S end‐plates are well developed. They are numerous, long, closely packed and often branched. On the other hand, the secondary subneural clefts of the P end‐plates are short, sparse and usually unbranched. Secondly, there seems to be a variation in AChE activity in the P end‐plates. Focal negative AChE areas are found in the subneural apparatus of some P end‐plates. It is concluded that the less well developed secondary subneural clefts and focal areas of negative AChE activity contribute to the paler staining of the P end‐plates.
Non‐random spatial distribution of mitoses in proliferating rat uterine epithelium
Authors: Purnell Dallas M. 
Published: February 2005

AbstractA non‐random spatial distribution of mitoses in proliferating rat endometrium was found by means of a quantitative microscopic technique. Nulliparous Lewis/Mai rats, 60–90 days of age, were given an intraperitoneal injection of colchicine (1 mg/kg) five hours prior to death, to arrest mitosis at metaphase. The middle one‐third of the right uterine horn was removed and fixed in Bouin's fixative for 24 hours. Several 5‐μm microtome sections were cut from dehydrated, paraffin‐embedded uterine tissue from each rat and stained with hematoxylin and eosin. Microtome sections of uterine horn which showed high endometrial mitotic activity, i.e., those obtained from rats killed in the metestrus phase of the estrous cycle, were selected for microscopic analysis. Using a binocular microscope equipped with an eye‐piece graticle, maps of uterine horn cross‐sections (3 non‐adjacent microtome sections/rat) showing the spatial distribution of mitoses along the surface of the uterine lumen were prepared. Data collected from the mitotic maps were: (a) the frequency of graticle squares containing mitoses and bounded on either side by graticle squares without mitoses; (b) the frequency of sequences of two or more adjacent graticle squares with mitoses; and (c) the frequency distribution of mitotically‐inactive intervals (number of graticle squares) between graticle squares enclosing mitoses. The observed frequency distribution of adjacent graticle squares with mitoses and the observed frequency distribution of spacing intervals between graticle squares with mitoses were examined for non‐randomness by generating from these data the Poisson frequency distributions expected assuming a random distribution. Goodness of fit between observed and expected distributions was tested using Chi‐square analysis.These analyses revealed, in each case, a significant deviation from randomness. Our data support a non‐random spatial distribution of mitoses in uterine epithelium and indicate that mitotic activity in rat endometrium occurs in localized spatial regions separated by relatively long regions of mitotically inactive endometrium.Possible mechanisms of production of a non‐random tissue distribution of mitoses are discussed.
Cyclic changes in ciliation of the oviductal epithelium in the pig‐tailed macaque (Macaca nemestrina)
Authors: Rumery R. E. , Gaddum‐Rosse P. , Blandau R. J. , Odor D. L. 
Published: February 2005

AbstractMany of the cilia in the oviducts of rhesus monkeys are formed in the follicular phase of the menstrual cycle, and lost in the subsequent luteal phase (Brenner, 1969a). This striking phenomenon has rarely been observed in other species, and its occurrence in human oviducts is a point of dispute. This study was designed to determine whether cyclic shedding and renewal of oviductal cilia occur in a primate species other than the rhesus monkey and to reveal the surface characteristics of the oviductal mucosa in a subhuman primate. Oviducts were removed from Macaca nemestrina females at three specific times during the menstrual cycle and examined by scanning electron microscopy. The fimbriae appeared to be extensively ciliated at midcycle but only sparsely ciliated in the early follicular and late luteal phases. Early in the cycle, large numbers of cells were seen in the process of ciliogenesis, but in the late luteal phase there were signs of ciliary degeneration and shedding. The ampullar epithelium showed similar though less dramatic changes, and the isthmus little change. Long‐term ovariectomy caused almost complete deciliation of the fimbrial and ampullar epithelium, but treatment of ovariectomized animals with estrogen for only a few days restored the epithelium to normal. Despite the high degree of variability in the mucosa, it was clear that the oviducts of M. nemestrina, like those of the rhesus monkey, undergo cyclic ciliogenesis and deciliation. The surface features of the oviductal lining in M. nemestrina are described here for the first time.
Non‐primary afferents to the principal cells of the rostral anteroventral cochlear nucleus of the guinea pig
Authors: Schwartz A. M. , Gulley R. L. 
Published: February 2005

AbstractThe non‐primary input to the soma of the principal cells of the rostral anteroventral cochlear nucleus (AVCN) of the guinea pig was defined by correlating data from freeze‐fractured and thin‐sectioned specimens. The principal cells receive three types of non‐primary terminals in addition to a single end bulb from the ascending branch of the auditory nerve. The first, the O‐boutons are irregularly shaped, medium‐sized boutons, containing oval synaptic vesicles. These cover about 13% of the soma and each makes from one to three crescent‐shaped axosomatic junctions. Paramembranous dense material is distributed symmetrically between the pre‐ and postsynaptic junctional membranes. The second, the F‐bouton, is a small, ovate bouton which occurs either singly or in small clusters and covers about 5% of the soma. This bouton, containing flattened synaptic vesicles, has a single, oval synaptic junction lined by thin, paramembranous densities distributed symmetrically between the pre‐and postsynaptic membranes. The third, the SR‐bouton, is a medium‐sized bouton containing small, round synaptic vesicles. These boutons cover about 4% of the soma, but more frequently contact dendrites in the neuropil. The junctional region of the bouton is poorly defined. Small tufts of dense material symmetrically line the cytoplasmic surfaces of the pre‐ and postsynaptic membranes along scattered, narrow undulations of the apposition. In freeze‐fracture replicas, several narrow troughs on the cytoplasmic leaflet frequently have a higher density of large intramembranous particles than adjacent membrane and may represent a diffusely organized active zone. No specializations are found on either leaflet of the postsynaptic plasmalemma opposite the non‐primary boutons. Correlation of the measurements from thin‐sectioned and freeze‐fractured material suggests that the oval, flattened, and small round vesiclecontaining boutons occur on the somata of the principal cells in a ratio of 6:3:1.
Scanning electron microscopy of microcorrosion casts; intracranial and abdominal microvasculature in domestic animals
Authors: Anderson Bettina G. , Anderson Wesley D. 
Published: February 2005

AbstractThe use of methyl methacrylate corrosion casts prepared from portions of the vascular system has made it possible to examine numerous and extensive areas of microscopic structures on a 3‐dimensional scale with the scanning electron microscope. By this means we have examined the arterial microvasculature of intracranial vessels among three domestic animal species. In addition, these vessels have been compared with the terminal branches of abdominal arteries in the dog. The results of this study suggest that the sphincteric control mechanisms of the vessels in the two regions may be structurally different from one another.In the case of the intracranial vessels, the terminal portion of the arteriole is continued by a precapillary arteriole composed of a chain‐like series of muscular constrictions. This is most suitably described as a precapillary sphincter area, which terminates at the capillary. In the abdominal vessels, the precapillary arteriole is generally followed by a single precapillary sphincter at the origin of the capillary. These morphological characteristics may account, in part, for the difference in response of vessels in these two regions in hypovolemic shock.
Development of the human optic disc: Light microscopy
Authors: Rhodes Roy H. 
Published: February 2005

AbstractHuman embryonic and fetal optic discs were studied in semithin sections stained with silver and toned with gold, in a series ranging from 7 to 21 weeks of gestation. The observations suggest that Bergmeister's papilla forms by proliferation of glial cells in the optic disc rather than by sequestration of retinal glia by axons growing through the region. A possible stimulus for such a glial proliferation is hypothesized to be traction on the anterior face of the disc exerted through the primary vitreous. The formation of the glial sheath of the hyaloid artery also appears to be a consequence of traction from the primary vitreous.
Developmental correlation between hypothalamic gonadotropin‐releasing hormone and hypophysial luteinizing hormone
Authors: Gross Douglas S. , Baker Burton L. 
Published: February 2005

AbstractConsiderable evidence indicates that the pituitary‐gonadal axis is active in the fetus, but little is known about the relative times in development when the brain begins to secrete gonadotropin‐releasing hormone (GnRH) and the hypophysis begins to secrete gonadotropin. The objective was to correlate the time of appearance of GnRH in the median eminence and organum vasculosum of the lamina terminalis (OVLT) with differentiation of LH‐gonadotropes in the hypophysis of the fetal mouse by means of immunocytochemistry. Mice were studied at 15, 16, 17 and 19 days of gestation with the peroxidase‐antiperoxidase (PAP) method of Sternberger. GnRH was first detected at 17 days of gestation in presumptive axons and axon terminals located adjacent to the superficial portal capillaries near the surface of the median eminence and close to the capillaries of the OVLT. LH‐gonadotropes also were found initially at 17 days of gestation. They were prominent in the ventral half of the pars distalis. Most of these cells were ovoid or slightly angular, and almost all abutted one of the numerous sinusoidal capillaries present at this age in development. The number and staining intensity of both LH‐gonadotropes and GnRH foci increased by 19 days. The close temporal relationship between the developmental appearance of GnRH and its target cell, the gonadotrope, provides further evidence that the potential for neuroendocrine control of gonadotropin secretion exists in the fetal mouse as early as 17 days of gestation.
The maturation of the rabbit fetal lung following maternal administration of pilocarpine
Authors: Smith Dennis M. , Shelley Sue A. , Balis John U. 
Published: February 2005

AbstractPilocarpine HCl, a parasympathomimetic drug, was administered to pregnant white rabbits in a daily subcutaneous injection of 5 mg/kg on days 24 through 27 of gestation. Fetuses from these animals and from salineinjected controls were obtained by caesarean section at day 28 of gestation. Light microscopic examination revealed thinner alveolar septa in the lungs of pilocarpine‐treated fetuses and, morphometrically, a significant increase in the number of mature type II cells, both per unit area and per 1,000 lung cells of any kind. Examination by electron microscopy revealed that the alveolar epithelium of pilocarpine‐treated fetuses demonstrated morphologic correlates of increased maturation. These included thinning of type I cells to form blood‐air barriers and substantial reductions in the glycogen content of both epithelial cell types. Type II cells of pilocarpine‐treated fetuses contained (as indicated by morphometric analysis) more and larger lamellar inclusion bodies, as well as more multivesicular bodies than those of controls. Biochemical determination indicated that the glycogen content of fetal lung, but not liver, was reduced significantly in the pilocarpine‐treated group. The findings of this study indicate that maternal administration of pilocarpine results in increased maturation of the fetal alveolar epithelium, thus providing a basis for the autonomic manipulation of fetal lung maturation.
A light microscopic study of the developing human neural retina
Authors: Rhodes Roy H. 
Published: February 2005

AbstractHuman embryonic and fetal eyes from 4 mm to 200 mm crownrump length (26 days to 21 weeks of gestation) were studied in 0.75‐μm sections impregnated with silver and toned with gold. The layer of Chievitz was formed by an inward migration of ganglion‐cell and Müller‐cell nuclei from the outer neuroepithelium and then, after further changes in nuclear location, the layer of Chievitz was cleared of ganglion‐cell nuclei to become the definitive inner plexiform layer. Müller‐cell nuclei later populated all retinal layers in the fetus. The argyrophilic Müller‐cell cytoplasm associated with neuronal development is discussed in relation to glia‐neuron interactions, with emphasis on the particular needs of retinal tissue.
Studies on the trophoblast‐epithelial complex during decidual induction in rats
Authors: Lundkvist Örjan , Nilsson Ove , Bergström Staffan 
Published: February 2005

AbstractStudies were undertaken to elucidate the role of the complex consisting of the trophoblast and uterine epithelial cells during decidual induction in rats. Animals with estradiol‐induced implantation after an experimental delay were used.In one experiment the ultrastructural changes of the complex were examined at 4‐hourly intervals from delay of implantation to the appearance of the Pontamine Blue Reaction, 24 hours after estradiol injection (24 h.a.e.). Transmission electron microscopy of the trophoblasts revealed signs of increased synthetic activity from 8 h.a.e. onwards, with formation of polyribosomes and glycogen‐like particles and dilation of the granular endoplasmic reticulum. The epithelial cells displayed signs of endocytosis, but no differences between blastocyst‐free and blastocyst‐containing uterine sites were noted. Occasionally, signs of membrane contacts between the trophoblast and epithelial cells were observed before 12 h.a.e., as revealed by transmission electron microscopy of uterine sites and by scanning electron microscopy of blastocyst surfaces. Later an attachment of the trophoblast onto the epithelial cells became evident. Since previous studies have shown that the stromal cells are influenced by the presence of a blastocyst about 12 h.a.e., the results are in accordance both with a humoral and with a contact‐mediated signal from the blastocyst to the endometrium.In another experiment attempts were made to ascertain whether a continuous influence of the complex upon the stroma is required for the maintenance of an ongoing decidual differentiation. Blastocysts were flushed out from the uterus 16–18 and 24–26 h.a.e. and on the following day the presence of uterine sites with a decidualizing stroma were sought for. The results suggest that the differentiating stroma is dependent upon the presence of an intact complex 16–18 h.a.e. but not 24–26 h.a.e. A continuous signal release from the complex to the stroma is therefore possible during the initial stages of the decidual reaction.