bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of progestin and androgen on the fine structure of the male reproductive tract of the rat. I. General effects and observations on the testis
Authors: Flickinger Charles J. 
Published: February 2005

AbstractThe combination of a progestin and androgen has received attention as a possible male contraceptive. The progestin is thought to reduce gonadotropin release and suppress spermatogenesis, while the sex accessory organs and male characteristics are maintained by the simultaneous administration of testosterone. In the present study, the histology and ultrastructure of parts of the male reproductive tract of rats treated with medroxyprogesterone (Provera, Upjohn) (1 mg/100 g body weight/day) alone and combined with testosterone (15, 30, or 100 μg/100 g/day) were studied following treatment for up to 16 weeks. The testes and epididymides of rats administered Provera alone or Provera and testosterone weighed less than those of control rats. The weights of the accessory glands of rats treated with Provera were greatly reduced; it was possible to maintain them at approximately control levels by simultaneously administering sufficient testosterone (100 μg/100 g body weight/day). The fertility of some of the animals was tested by caging them with female rats, and none of the treated rats tested in this way was fertile.Similar microscopic alterations were present in the testes of animals administered Provera alone or Provera and different levels of testosterone. Spermato‐gonia, spermatocytes, and early spermatids were abundant in treated rats and did not show ultrastructural changes. However, many degenerating or necrotic spermatids of the cap phase (approximately stages 6–7 ) and later were present. Late spermatids of the acrosome and maturation phases were rare. Some necrotic spermatids were surrounded by Sertoli cells, and parts of spermatids lay within lysosome‐like structures in the cytoplasm of Sertoli cells. Many large lipid droplets were also present in Sertoli cells of treated rats. Leydig cells were smaller in treated animals than in control rats. The results suggest that germ cells can develop up to cap phase spermatids but then undergo degeneration. These alterations in spermatogenesis may be responsible in large part for the antifertility effect of the progestin and androgen combination.Some rats were permitted to recover following the end of treatment. The microscopic appearance of the testis returned to normal within three to six weeks, although epididymal alterations persisted in some animals six weeks after the end of treatment. By 9 to 12 weeks after the end of treatment the reproductive organs had a normal microscopic appearance in all the rats studied.
Innervation of the rat harderian gland by adrenergic and cholinergic nerve fibres
Authors: Huhtala Antero , Huikuri Kauko T. , Palkama Arto , Tervo Timo 
Published: February 2005

AbstractThe innervation of the rat Harderian gland was studied using histochemical methods for catecholamines and acetylcholinesterase (AChE). Selective denervations were performed to investigate the neural connections of this gland with various ganglia.Light microscopically the AChE‐positive nerves seemed to run as thick bundles in the intertubular connective tissue. These bundles sent finer branches around the acini. The blood vessels, localized in the connective tissue septa, were surrounded by a dense plexus of AChE‐containing fibres. By electron microscopy, the AChE‐positive fibres were seen to terminate near the myoepithelial cells surrounding secretory cells. These fibres were also observed in contact with the blood vessels and occasionally close to the secretory cells. Fluorescent adrenergic nerves surrounded the blood vessels. Some fibres were also observed in the interlobular tissue.All the AChE‐containing nerves degenerated after cutting the zygomatic nerve. On the other hand, removal of the ciliary ganglion or the superior cervical ganglion, or stereotactic coagulation of the ophthalmic nerve did not affect these nerves. The fluorescent adrenergic fibres disappeared following both removal of the superior cervical ganglion and coagulation of the ophthalmic nerve. These fibres were intact after removal of the ciliary ganglion.
An autoradiographic study of long‐term follicular development in the cyclic hamster
Authors: Chiras Daniel D. , Greenwald Gilbert S. 
Published: February 2005

AbstractThe time required for ovarian follicular development in the cyclic hamster was determined by marking follicles with [3H]‐thymidine on day 1 of the estrous cycle (day of ovulation) and by following their fate over the next three cycles by autoradiography. A model of follicular development was formulated, based on the total number of follicles and the changing percentage of labelled follicles with time.It was estimated that 20 days elapsed before a preantral follicle with two to three layers of granulosa cells (stage 1) was able to ovulate. Follicles spent eight days in stage 1 and an additional eight days in stage 2 (4‐5 granulosa layers). Preantral follicles entering stage 3 (6‐7 granulosa layers) and 4 ( 8 layers) on day 1 of the cycle ovulated four days later.Approximately 30 follicles per ovary entered and left stage 1 each cycle, representing a 50% turnover. Of the follicles leaving stage 1, about 50% were transformed into stage 2 follicles; the remaining ones underwent atresia. Stage 2 follicles also had a 50% turnover each cycle. Half of the stage 2 follicles underwent atresia; the remainder developed into stages 3 and 4 follicles Fifty percent of the stages 3 and 4 follicles present on day 1 of the cycle ovulated at the next estrus with the remainder undergoing atresia.
Cell turnover in the beak of Rana pipiens
Authors: Kaung Hue‐Lee Cheng , Kollros Jerry J. 
Published: February 2005

AbstractRana pipiens tadpoles were injected with 3H‐thymidine at different stages to label basal cells of the horny beaks, the keratinized oral specializations of many anuran tadpoles. Cells in the column and sheath of the beak are derived from the basal layer. Movement of the labeled cells in beak columns can be traced, permitting calculation of the rate of cell addition into the columns. With the counts of the total number of column cells and cell addition rate, the rate of apical cell loss from a column throughout the larval stages can also be calculated. The rate of cell addition decreases steadily from stage III through stage XX, in all portions of both beaks. The rate of change of these column cell addition rates is similar among middle and lateral portions of both upper and lower beaks. There is a relatively constant rate of cell loss until stage XII or XIII. It then increases sharply, and the beaks are completely lost at stages XIX or XX. The longer, lower beak columns have a much faster cell loss rate than do the upper beak columns at late larval stages. Life spans for cells that move to the sheath may be about one‐half those for cells that enter the beak columns. It is suggested that thyroid hormone accelerates the rate of column cell loss.
Granule release by polymorphonuclear leukocytes treated with the lonophore A23187
Authors: Sannes Philip L. , Bank Harvey L. , Moore Patrick L. , Spicer Samuel S. 
Published: February 2005

AbstractPolymorphonuclear leukocytes (PMN's) incubated three to eight minutes at 37°C in medium containing 1 × 10−6M of the ionophore antibiotic A23187 released their cytoplasmic granules into the extracellular medium. Transmission electron microscopy of treated cells showed microfilament bundles extending between adjacent granules within the cytoplasm and between granules and the plasma membrane. Tiny dense projections (beads) 8‐12 nm in diameter were observed along segments of the cytoplasmic surface of the plasma membrane with a periodicity of 20–30 nm. These beads were observed on the plasma membrane only in the vicinity of intra‐ or extracytoplasmic granules. The structural relationships of the beads with the plasma membrane micro‐filaments suggest they play a role in the process of ionophore‐induced granule release from polymorphonuclear leukocytes.
Embryologic origin of various epithelial cell types in the thyroid gland of the rat
Authors: Wollman Seymour H. , Hilfer S. Robert 
Published: February 2005

AbstractVentral pharyngeal outpocketings and ultimobranchial out‐pocketings from the 14‐day‐old fetus of the Fischer rat were isolated before they fused to form thyroid glands. The outpocketings were implanted into different kidney capsules of adult male Fischer rats, and were allowed to grow for several months. Transplants were then excised and examined by electron microscopy. The ultimobranchial outpocketing gave rise to two types of follicles. One contained ciliated cells, cells with an abundant agranular reticulum, U cells with basal hemidesmosomes, and two types of cells with secretory vesicles. The other contained C cells separated from the follicular lumen by a single flat fiber‐con‐taining cell. The ventral outpocketing formed typical thyroid epithelium making up the usual thyroid follicles differing from follicles in the thyroid in situ by the absence of C cells. These follicles were functional as determined by autoradio‐graphic studies with 125I but differed from thyroid follicles in situ with respect to size distribution. The results suggest that (1) in the adult thyroid gland the C cell in the usual follicle is an ultimobranchial contribution and (2) the so‐called ultimobranchial follicle is ultimobranchial in origin but that the typical thyroid epithelium in mixed follicles of U cells and typical thyroid epithelium is a ventral contribution. The reason for the absence in the thyroid gland in situ of the variety of other cell types observed in ultimobranchial transplants is unknown.
Contact sites between lymphoid cells of the bursa of fabricius, in vivo and in vitro
Authors: Holbrook Karen A. , Perkins William D. , Glick Bruce 
Published: February 2005

AbstractContact sites between lymphocytes and between lymphocytes and macrophages were demonstrated by electron microscopy in the lymphoid follicles of the bursa of Fabricius. When compared with nonspecialized regions of the cell membranes, these contact sites were characterized by a decreased intercellular distance, subplasmalemmal densities and coated pits. Microfilaments, microtubules and coated vesicles of the subjacent cytoplasm were frequently associated with these contact sites. When the same cells were isolated and introduced into culture, they formed cluster‐like assemblies in which cells were closely approximated along broadly contacting surfaces. The morphology of the sites appeared to involve primarily the plasma membrane (including coated pits) and the cell coat. These observations indicated that the same cells of a given lymphoid tissue can form one type of contact site in vivo and another, dissimilar type of contact site, in vitro.
Calcium localization in normal rachitic, and D3‐treated chicken epiphyseal chondrocytes utilizing potassium pyroantimonate‐osmium tetroxide
Authors: Carson Freida L. , Davis W. L. , Matthews J. L. , Martin J. H. 
Published: February 2005

AbstractNormal, rachitic, and vitamin D3‐replete chicken growth plates were studied utilizing the potassium pyroantimonate‐osmium tetroxide procedure. A marked membrane and mitochondrial calcium was revealed in all specimens in the maturing and early hypertrophic zones which disappeared as heavy matrix mineralization began.The most significant difference shown in the specimens was in the marked intracellular lipid content of chondrocytes in all zones of the rachitic and D3‐replete growth plates. There was negligible lipid present in normal specimens.It is suggested that as most of the mechanisms postulated as necessary for calcification are present in rachitic chicks, perhaps the increased intracellular lipid pool results from the formation of abnormal lipids for insertion into the plasma membrane and thus prevents normal calcium transport.Chains of intracellular vesicles were also visualized in maturing and hypertrophic chondrocytes. These were more often seen in rachitic growth plates and in increased numbers in the early D3‐replete specimens. The etiology is unknown at the present time.
The blood‐testis barrier and its formation relative to spermatocyte maturation in the adult rat: A lanthanum tracer study
Authors: Russell Lonnie D. 
Published: February 2005

AbstractAn electron‐opaque substance, lanthanum, was utilized to determine when germ cells of the rat first cross the blood‐testis barrier in adult spermatogenesis. Intravascularly perfused lanthanum was shown to surround all spermatogonia, preleptotene spermatocytes and early leptotene spermatocytes of Stage IX in the adult rat testis. Lanthanum was excluded from the spaces around more mature cells by newly‐formed tight junctions between adjoining Sertoli processes. These processes had previously intervened between the leptotene cells and the basal lamina. The results are in close agreement with those of a previous study (Russell, '77a) which indicated that leptotene cells are the first cells of adult spermatogenesis to enter the intermediate compartment and to reside beyond a permeability barrier.
Growth, protein content and distribution of early pig embryos
Authors: Anderson L. L. 
Published: February 2005

AbstractDevelopment of porcine conceptuses included transitions of five stages: blastocysts of spherical, ovoid, and tubular forms containing an embryonic disc and trophoblast, extremely elongated filamentous blastocysts, and stages of embryogenesis between days 9 and 18 after mating. Embryonic survival was reduced by 17% during this period. In this litter‐bearing species, intense alteration in distribution patterns occurred at days 11 and 12, when blastocysts rapidly elongated to filamentous forms. Increased embryo mortality did not result from rapid changes in distribution patterns of conceptuses within the same uterine horn at this time. Filamentous blastocysts quickly reached lengths often exceeding 60 cm, and these conceptuses became regularly spaced with no overlap of tubular membranes from other embryos in that horn. The number of concep‐tuses within a uterine horn ranged from 1 to 13. Protein in individual concep‐tuses was used as an indicator of growth and denoted exponential increase, but at a lower rate for blastocysts of spherical, ovoid, and tubular forms as compared with that found in filamentous blastocysts and embryogenesis stage conceptuses. Growth of a conceptus, based upon its protein content, was independent of the developmental stage or potential loss of those neighbors nearest that conceptus.
Synergistic effects of prolactin and testosterone in the restoration of rat prostatic epithelium following castration
Authors: Thompson Sue Ann , Heidger Paul M. 
Published: February 2005

AbstractProlactin is known to enhance the uptake and metabolism of testosterone in male accessory sex organs and to increase the weight of accessory sex organs from castrated rats over those from controls treated with testosterone alone. The present study was directed toward defining fine structural changes detectable with scanning and transmission electron microscopy which might accompany such responses. Accordingly, rat ventral prostrate gland was examined from castrated animals which had received testosterone propionate and ovine prolactin singly or together, or which had received vehicle only. Unoperated ani‐mals served as additional controls. Post‐castration glandular atrophy was not influenced by prolactin treatment alone. Testosterone restored epithelial height, secretory product, Golgi complexes and rough endoplasmic reticulum, such that cellular and tissue morphology was generally indistinguishable from that of unoperated controls. Prostatic tissue from animals given testosterone and prolactin simultaneously exhibited pleomorphic, cytoplasmic apical projections which extended into the acinar lumen. Transmission electron microscopy demonstrated that these blebs were devoid of organelles and microvilli; scanning electron microscopy revealed that the blebs were highly wrinkled and more numerous than were the projections observed in tissue from animals treated with testosterone alone, or in tissue from unoperated controls. It is suggested that such blebbing may reflect enhanced apocrine secretion in prolactin/testosterone stimulated restoration of the prostate gland in castrated rats.
Spatial orientation of microtubules in contractile fibroblasts in vivo
Authors: Rudolph Ross , Woodward Marilyn 
Published: February 2005

AbstractContracting fibrous tissues from skin wounds in pigs, and scars around silicone implants in humans, contained fibroblasts that had multiple bundles of 60‐80 Å microfilaments with electron‐dense bodies, features typical of contractile fibroblasts both in vivo (myofibroblasts) and in vitro. These in vivo fibroblasts contained many 220 Å diameter microtubules, which paralleled plasma membranes in the long axis of the cells. The spatial orientation of the microtubules in these myofibroblasts strongly suggests a bracing or scaffolding function.
Surface morphology of mouse and rat thymic lymphocytes: An in situ scanning electron microscopic study
Authors: Bhalla Deepak K. , Karnovsky Morris J. 
Published: February 2005

AbstractThe present paper deals with a scanning electron microscopic investigation which was undertaken in order to make a direct study of geometrical conformations of thymocytes, to determine the effect of external mechanical forces and finally to analyse the relation of the cell surface morphology to the differentiation and release of thymocytes into circulation. Thymocytes in situ revealed a striking polyhedral configuration with distinct edges and angles that permit a close orientation of cells in a minimum space. This conformation is probably acquired under the influence of forces in the microenvironment of the cells. The immature thymocytes in the cortex were smooth surfaced and constituted a homogeneous population with regards to surface morphology except for slight variations in the size and angles of various facets of the polyhedra. A minority of the cell population occupying the medulla, however, exhibited a departure in possessing surface undulations and stubby protuberances. Thymocytes isolated in suspension and those in postcapillary venules of thymus did not show the polyhedral shape characteristic of the cells in thymic tissue. They were always rounded, with their surfaces often exhibiting undulations or microvilli The variations observed in situ are discussed in light of external mechanical forces, cell surface characteristics and the inherent properties of differentiating thymocytes.
Cellular responses to experimental inhibition of collagen degradation in the postpartum rat uterus
Authors: Tansey Terese R. , Padykula Helen A. 
Published: February 2005

AbstractRapid collagen breakdown in the postpartum rat uterus is accompanied by rising collagenase activity (Jeffrey and Gross, '70) and a transient infiltration of the stroma by heterophils, eosinophils, monocyte‐macro‐phages, lymphocytes, and plasma cells (Padykula and Campbell, '76), cells usually associated with inflammatory response. This uterine catabolism is initiated soon after birth while blood estrogen and progesterone levels are low. To investigate the hormonal factors involved in regulation of this postpartum stromal differentiation, we analyzed the cytological effects of experimentally elevating progesterone and estradiol levels in the peripartum period by following the protocol of biochemical experiments that have demonstrated inhibition of collagenase activity by progesterone (Koob and Jeffrey, '74) and estradiol (Ryan and Woessner, '74).Prolonged gestation (progesterone, 10 mg/day starting on day 19 gestation) was used as a condition to prevent the prenatal drop in blood progesterone; this treatment was the most effective in blocking postpartum stromal differentiation. It preserved the state of prepartum uterine differentiation and most importantly it prevented monocytic‐macrophagic conversion. Progesterone (40 mg/day) given at birth delayed but did not block stromal differentiation during the first 48 hours; by 72 hours collagen loss was extensive in both control and progesterone‐treated rats and numerous macrophages were present. Estradiol (100 μg/day) given at birth caused a greater delay in stromal differentiation than progesterone given at birth; for approximately 48 hours the number of eo‐sinophils, heterophils, and macrophages was less than normal. By day 3 the number and distribution of the macrophages resembled that of the day 1 control uteri. Overall these experiments indicate that the low estrogen and progesterone levels at birth are essential for normal stromal regression. Since these transient cells originate from the blood, the temporal pattern of their emigration into the uterus may be under hormonal control. Experimental disturbance of this pattern influences the course of collagen resorption.
A new corrosion casting technique
Authors: Nerantzis C. , Antonakis E. , Avgoustakis D. 
Published: February 2005

AbstractA technique is described, employing polyester as the injection material, for preparing a casting of all cardiac vessels or of arteries or veins separately. This technique was used in 10 bovine and 40 fresh human hearts.The technique is simple, rapid, economical and the required equipment is available in the average laboratory. The extent of vascular penetration is controlled by the viscosity of the polyester solutions, some of which at a certain density can penetrate through the net of capillaries with an injection pressure of no more than 220 mm Hg.Our technique does not require any special handling of the heart and it makes no difference to the quality of the casting whether the blood is drained or flushed from the vessels prior to the perfusion.There is no noted shrinkage or crumbling of our specimens stored at room temperature. The heart size, configuration and the anatomical relationship of the cardiac vessels are preserved without the need for casting cardiac chambers. The injection materials are cheap, easily transported and can be stored without special care. Injection, solidification and corrosion are carried out at room temperature.
Induction of lipid droplet accumulation in cardiac muscle cells of guinea pigs and mice: An analysis of the effects of reserpine and fasting
Authors: Iacovitti Lorraine , Gershon M. D. 
Published: February 2005

AbstractReserpine has been demonstrated in previous studies to induce the accumulation of lipid droplets in ventricular cardiac muscle cells of bats and this effect has been attributed to mediation by the sympathetic nervous system. The present study was done to evaluate the species specificity of this action of the drug. Reserpine caused lipid droplet accumulation in cardiocytes of guinea pigs and mice. However, in contrast to the action of the drug in bats, this action of reserpine in guinea pigs and mice could not be antagonized by chemical sympathectomy with 6‐hydroxydopamine or by treatment of animals with phenoxybenzamine, atropine or hexamethonium. Like reserpine, fasting for as little as 24 hours induced lipid droplet accumulation in cardiocytes of guinea pigs and mice. This effect also could not be prevented by treatment with 6‐hydroxydopamine indicating that the sympathetic nervous system was not involved in its mediation. Force‐feeding guinea pigs given reserpine prevented the accumulation of lipid droplets normally induced by this drug. It is concluded that the lipid droplets accumulation in the hearts of guinea pigs that follows administration of reserpine is not due to a direct cardiotoxicity of the drug but is secondary to the failure of drug‐treated animals to eat. Since the autonomic nervous system appears to mediate reserpine's cardiotoxicity in bats, the species difference revealed by these experiments probably results from an underlying physiological difference in the nervous systems of these animals.