bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maintenance of gonadotrophs in pituitary autografts under the kidney capsules of female rats given sex hormones or LRH
Authors: Shiino Masataka , Fujihara Noboru , Rennels Edward G. 
Published: February 2005

AbstractFemale Sprague‐Dawley rats were hypophysectomized and the anterior pituitary gland was immediately placed under the kidney capsule. For 1 week after surgery, groups of pituitary autograft‐bearing animals were treated with twice‐daily injections of estradiol 17β (E), progesterone (P), estradiol 17β and progesterone (EP), or luteinizing hormone‐releasing hormone (LRH). Within 2–4 hours following the last injection, the pituitary grafts were removed and placed into organ culture. They were maintained in culture with or without added LRH (10−7 M) for 1 hour at 37°C. The culture media were then frozen for later radioimmunoassay of FSH and LH. The tissues were kept in culture for an additional 24 hours, at which time they were fixed and prepared for immunocytochemistry or electron microscopy.Results showed that treatment of the animals with E, EP, or LRH enhanced the release of FSH and LH into the culture media, and that the release of these hormones was increaed further by acute incubation with LRH.The ultrastructure of the gonadotrophs was well maintained by treating the animals with E or the combination of E and P or with LRH. Graft tissue from animals treated with LRH, which was incubated subsequently for 24 hours with LRH, showed the best maintenance of gonadotroph morphology. This experimental procedure should be useful for obtaining gonadotrophs for use in establishing gonadotroph cell lines.
Immunoreactive calcitonin in the rat anterior pituitary gland and its localization in thyrotrophs
Authors: Watkins Wayne B. , Moore Robert Y. 
Published: February 2005

AbstractThe distribution of those cells in the anterior pituitary gland of the rat which stain immunohistochemically with rabbit anti‐human calcitonin serum has been examined. Immunoreactive cells were confined primarily to the ventral surface of the gland and possessed both a distribution and morphology distinct from the corticotrophs. Staining of serial thin sections with rabbit anti‐rat TSH‐subunit serum resulted in an immunoreaction in those cells that stained for calcitonin. However, not all the thyrotrophs gave a positive immunoreaction for calcitonin. It is concluded from this study that it is inappropriate to attribute calcitonin as being part of the 31K‐dalton precursor for adrenocorticotropin, a hypothesis that was proposed earlier. In the immunohistochemical reaction with anti‐calcitonin serum, it was found that relatively high concentrations of antigen (500 μg/ml) were required in absorption experiments in order to inhibit staining. Furthermore, the staining of thyrotrophs with the anti‐calcitonin serum was inhibited after preadsorption of the primary antiserum with excess rat β‐TSH (1000 μg/ml). Because of these immunochemical characteristics, it is questionable whether the calcitonin‐like material observed in the rat pituitary gland is chemically identical to that of thyroidal calcitonin.
Functional classification of cell types in the growth hormone‐ and prolactin‐secreting rat MtTW15 mammosomatotropic tumor with ultrastructural immunocytochemistry
Authors: Baskin Denis G. , Erlandsen Stanley L. , Parsons Jonathan A. 
Published: February 2005

AbstractThe aim of this study was to identify the neoplastic endocrine cells which contain growth hormone (GH) and prolactin (PRL), in the MtTW15 mammosomatotropic tumor, with ultrastructural immunocytochemistry. We used tumors recovered after 5 to 11 weeks of tumor development, from normal (untreated) rats and from rats treated with the progestin medroxyprogesterone acetate (MPA)—a stimulator of GH secretion in these tumors. Immunocytochemical staining was done with the peroxidase‐antiperoxidase technique on ultrathin sections of tumor that had been fixed in glutaraldehyde and postfixed in osmium tetroxide. Immunospecific staining for PRL was found over small (150 nm) secretion granules, whereas staining for GH was deposited on the larger secretion granules (250 nm). Tumors from MPA‐treated rats contained profuse numbers of neoplastic cells with large, GH‐positive granules. Immunocytochemical staining for GH and PRL was also found in crinophagic, lysosome‐like inclusions, particularly in cells that contained many secretion granules. The results support the hypothesis that GH and PRL are produced by separate neoplastic endocrine cell types in the MtTW15 mammosomatotropic tumor, and demonstrate the value of ultrastructural immunocytochemical analysis for functional classification of cell types in chromophobic pituitary adenomas.
Electron‐microscopic cytochemical studies on the secretory process in rat prolactin cells in primary culture
Authors: Tougard C. , Picart R. , Tixier‐Vidal A. 
Published: February 2005

AbstractThree aspects of the secretory process in male rat prolactin (PRL) cells grown in primary cultures for 7–14 days have been investigated by cytochemical methods. The subcellular localization of prolactin has been studied using preembedding or postembedding immunocytochemical methods after various fixatives. With postembedding method, PRL is localized essentially in secretory granules. The maximum intensity of staining is obtained with PAF fixative. With the preembedding method, subcellular localization of the staining varies depending on the fixative. After PAF‐fixation, positive staining is observed on secretory granules, ground cytoplasm, the outer face of some RER cisternae and, in a few cells, on the innermost Golgi cisternae, as well as on masses of condensing secretory material. After Ohtsuki's hypotonic fixative followed by saponin permeabilization, PRL is visualized within the totality of RER cisternae, including the perinuclear cisternae and the peripheral saccules on the cis‐Golgi face. Secretory granules are unstained. Membrane traffic was investigated using the Con A‐HRP indirect method as a tracer of surface saccharides. Plasma membrane, coated with Con A‐HRP at 4°C, is slowly internalized at 37°C. This involves both randomly distributed invaginations and capping. The final step of endocytosis (1–2 hours) is located in the Golgi zone, where very few smooth membranes are stained. In contrast, a conspicuous deposit is found around the dense content of secretory granules. This suggests a recycling of internalized membrane and a transfer of Con A‐HRP from the inner face of smooth cisternae to the secretory material. The internalization of Con A‐HRP‐coated membrane leads to an inhibition of PRL release starting after 30 minutes. This is accompanied by a marked increase of acid phosphatase activity, mostly around forming and mature secretory granules.
Immunocytochemical demonstration of anterior pituitary hormones in the pars tuberalis of long‐term hypophysectomized rats
Authors: Ordronneau Paul , Petrusz Peter 
Published: February 2005

AbstractThe hormone‐containing cells of the pars tuberalis of the rat adenohypophysis were studied, 4–5 months after hypophysectomy, with a double bridge immunocytochemical technique and with antisera directed against the hormones of the pars distalis. Corticotropes, lactotropes, somatotropes, thyrotropes, and gonadotropes were found in the pars tuberalis of all animals. These cells are well situated to receive blood, nerve terminals, and tanycyte processes from the median eminence and, thus, to be influenced by the chemical messengers from the hypothalamus. It is concluded that the pars tuberalis has to be regarded as a potential source of adenohypophyseal hormones in an animal model traditionally considered to be free of such hormones.
Role of somatostatin in the modulation of hypophysial growth hormone production by gonadal steroids
Authors: Gross Douglas S. 
Published: February 2005

AbstractGrowth hormone‐release‐inhibiting hormone (somatostatin) has been localized in several central nervous system sites, but the contribution of somatostatin in these various loci to the control of growth hormone (GH) production is unclear. In the present study, the efficacy of castration, alone, or with subsequent gonadal steroid administration, in modulating hypophysial GH production was examined, and the response of somatostatin‐containing nerve endings in the median eminence and the organum vasculosum of the lamina terminalis (OVLT) was evaluated by means of immunocytochemistry. Orchidectomy reduced the size and number of immunoreactive GH‐cells, and testosterone administration prevented this change. Ovariectomy appeared to stimulate the somatotropes, but this effect was neither as dramatic nor as consistent as the effect of castration in the male. Administration of estradiol, however, resulted in a marked reduction in the number, size, and GH content of somatotropes in all animals examined. Somatostatin was localized in the external lamina of the median eminence and in nerve endings surrounding the core of capillaries in the OVLT. Only the median eminence responded to steroid manipulations with a visible change in the immunoreactive pool of somatostatin, with a decrease following orchidectomy, which was reversible by testosterone treatment, and an increase following ovariectomy, which was reversible by estradiol treatment. However, as in the GH responses to steroid manipulations, the somatostatin responses were more variable in females than in males.These results suggest that: (1) testosterone promotes and estradiol, at least at high doses, inhibits storage of GH in the anterior pituitary; (2) these changes in GH production may be regulated, in part, by altered somatostatin release from the median eminence into the hypophysial portal blood; and (3) somatostatin in the OVLT may not be involved in the steroid‐induced modulation of GH production.
Morphology of the mammotrophs and gonadotrophs in the anterior pituitary gland of rats with protein‐calorie malnutrition
Authors: Herbert Damon C. 
Published: February 2005

AbstractThe structure of the anterior pituitary gland of rats with protein‐calorie malnutrition was studied at the light and electron microscopic levels. Male Sprague‐Dawley rats were fed a low‐protein diet from 20 to 50 days of age. The hypophyses from these animals, along with those from age‐matched controls, were then removed and fixed for light microscopic immunocytochemical analyses, using anti‐rat PRL or anti‐ovine LHβ serum, or for routine ultrastructural study.The overall number of mammotrophs and gonadotrophs appeared to be unaffected by the deficiency in dietary protein. However, the nuclei, in both cell types, were significantly smaller in the malnourished rats. Cytoplasmic volume was also apparently less than in control rats, leading to the “crowding” of adjacent cell types. Additionally, in the malnourished rats, the mammotrophs assumed a less polygonal profile, while the gonadotrophs, which were more irregularly shaped in the central zone, rarely displayed the negative image of a Golgi complex. Ultrastructurally, the mammotrophs in the experimental rats had a less extensively developed granular endoplasmic reticulum and Golgi complex. The number of secretory granules was not different; however, their size was markedly less and their shape was round to ovoid, rather than pleomorphic. Two types of gonadotrophs were distinguished, based on the classification of Kurosumi et al. ('76). The type‐I cell (former “FSH” cell) had a smaller Golgi complex, less vesicular endoplasmic reticulum and smaller secretory granules. The major alteration in the type‐II gonadotroph (former “LH” cell) was the smaller size of the secretory granules.The morphological changes found in this study support our previous physiological observations (Herbert, '80), which demonstrate that prolactin and gonadotrophin secretion are severely impaired in rats suffering from protein‐calorie malnutrition.
Relationship of intracerebral pituitary grafts to central neuropeptide systems
Authors: Knigge Karl M. 
Published: February 2005

AbstractVariable amounts of pituitary tissue from neonatal or 30‐day‐old donor rats were implanted in the recessus triangularis or third ventricle of hypophysectomized male host rats. The pituitary tissue was implanted either immediately or 30 days after hypophysectomy of the host rat. Grafts from donors of either age were capable of maintaining a significant degree of testicular weight in one‐third of the implanted animals. Neonatal grafts were not capable of restoring testicular weight when implanted 30 days after hypophysectomy. Final body weights of all graft‐bearing animals were greater than those of hypophysectomized controls. The pars distalis of all grafts contained large numbers of cells immunoreactive for LH, GH, and ACTH; TSH‐immunoreactive cells were sparse. Prolactin‐positive cells were extensive in grafts of animals in which the tests were maintained, and virtually absent in grafts of animals with atrophic tests. The fiber systems of three central neuropeptides, LRF, SRIF, and ACTH, were stained and found not to enter the graft. The results suggest that pituitary grafts in the third ventricle may receive their hypophysiotropic neuropeptides from the CSF.
Surface interaction in vitro between sertoli cells and germ cells at different stages of spermatogenesis
Authors: Ziparo Elio , Geremia Raffaele , Russo Mario A. , Stefanini Mario 
Published: February 2005

AbstractThe presence of surface‐recognition mechanisms between somatic and germ cells of the seminiferous epithelium has been studied in the rat by an assay in vitro based on the ability of homogeneous populations of spermatogenic cells, at specific differentiative stages, to adhere to monolayers of cultured Sertoli cells. The results show that germ cells adhere specifically to Sertoli cells and that the adhesion is dependent on the differentiative stage of the germ cells. Pachytene spermatocytes show the highest ability to adhere and form typical junctional specializations with the underlying Sertoli cells, while round spermatids adhere much less to the substrate. The possible regulative role of a somatic cell‐germ cell interaction is discussed.
Morphometric study of endomyocardium and epimyocardium of the left ventricle in adult dogs
Authors: Gerdes A. Martin , Kasten Frederick H. 
Published: February 2005

AbstractQuantitative light‐ and electron‐ microscopic data are reported for the endomyocardium and epimyocardium of the left ventricle in adult dogs. The endomyocardium has a markedly lower capillary density, and larger myocyte cross‐sectional area, than the epimyocardium. The sarcolemmal‐surface/cell‐volume ratio is significantly less in endocardial myocytes. No regional differences were found with regard to capillary diameter, interstitial space volume, or volume percent occupied by blood vessels and myocytes. Likewise, there are no differences in proportions of cardiac cell volume occupied by myofibrils (57%), mitochondria (25%), nuclei (1.5%), T tubes (1.2%), and sarcoplasmic reticulum (2.0%). The ratios of surface areas of T tubes and SR to their respective volumes and to cell volumes do not vary with transmural location. The regional differences and similarities are discussed in relation to general problems of blood flow in the heart and cardiac hypertrophy.
The surface morphology of embryonic and adult chick lens‐fiber cells
Authors: Kuszak J. , Alcala J. , Maisel H. 
Published: February 2005

AbstractThe surface morphology of lens fibers in embryonic and adult chicken lenses has been studied by scanning electron microscopy. As the elongating epithelial cells enter into a state of terminal differentiation they elaborate a number of cellular processes interconnecting neighboring fibers. The interlocking devices take the shapes of balls on a short stalk, tonguelike flaps, and fingerlike processes that fit into complementarily shaped sockets, imprints, and fingerprints, respectively, of adjoining fibers. Gap junctions comprising more than 50% of the fiber‐cell membrane may serve as ultrastructural interlocking devices. The interlocking devices and gap junctions are probably necessary to maintain fiber order—a critical requirement for lens transparency. With increased maturation, the uniform morphology of the fibers and their interlocking devices is lost. The highly repetitive ordered alignment of young uniformly shaped fiber cells acts to minimize large‐particle scatter. The results of this study show a progressive loss of uniform shape and order in chicken fibers of advanced maturity. This phenomenon of lens development may be the basis for the increase in light scattering seen in aged lenses of other species such as man.
An elementary introduction to stereology (quantitative microscopy)
Authors: Elias Hans , Hyde Dallas M. 
Published: February 2005

AbstractStereology is a branch of applied mathematics used for the three‐dimensional analysis of organs and materials from two‐dimensional measurements. Stereologic methods are versatile, easily understood, and simply applied.This paper provides anatomists with a practical guide to stereologic techniques and concepts and to ancillary morphometric methods. These methods allow investigators to calculate volume, surface, and numerical densities; make shape determinations; and calculate size distributions for spheres and rotatory ellipsoids. Other topics covered in this article include sampling methods, correction factors for shrinkage and section thickness, index of folding, automated and semiautomated image analysis, and three‐dimensional reconstruction from serial sections.
Primary cilia of the corneal endothelium
Authors: Gallagher Betty C. 
Published: February 2005

AbstractA primary cilium is a normal component of every rabbit corneal endothelial cell, rather than being a rare or sporadic organelle, as previously believed. In common with other cilia of this type it possesses an axonemal organization of 9+0 which converts distally to 8+1; it occurs only one per cell; and the basal body is accompanied by a proximal centriole. Additional structures associated with the basal body are nine transitional fibers, four striated satellite arms, and several rootlets. Ladderlike structures extend between the two centrioles to form the wall of a barrel. Reexamination of primary cilia from other tissues indicates that the ultrastructure of endothelial cilia may be characteristic of primary cilia in general.
The ability of localized implants of whole or minced dermis to disrupt pattern formation in the regenerating forelimb of the axolotl
Authors: Tank Patrick W. 
Published: February 2005

AbstractThe ability of localized grafts of dermis to alter pattern formation in the regenerating limb of the axolotl was studied. Longitudinal pieces of skin (1/4 of the circumference of the limb) were removed from either the anterior or the posterior surface of the upper forelimb. Epidermis was removed by immersion in versene followed by mechanical stripping. The resulting dermis was cross transplanted directly beneath the skin on the opposite side of the limb from which it originated. After 5 days of healing each limb was amputated through the graft at the midpoint of the humerus. High percentages of multiple regenerates resulted. Similar results were obtained when dermis was minced into 1 mm3 fragments prior to cross‐transplantation. Freezing or x‐raying (2000 rads) the grafts prior to cross‐transplantation abolished the effect. Dermis obtained from head skin rarely caused multiple regeneration when implanted into the upper forelimb followed by amputation 5 days later. These results demonstrate that addition of dermis to an intact limb stump profoundly alters pattern formation during regeneration. The effect is dependent upon viable cells that are capable of cell division.
Neurons of the basolateral amygdala: A Golgi study in the opossum (Didelphis virginiana)
Authors: McDonald Alexander J. , Culberson James L. 
Published: February 2005

AbstractThe cytoarchitecture of the opossum basolateral amygdala was studies using Golgi techniques. The neuronal morphology was similar in all nuclei of the basolateral complex, and three distinct cell classes were recognized. Class I neurons, which vary in size in different nuclei, have spiny dendrites and long, projection axons. Axon hillocks and initial axonal segments often have spinous protrusions, while more distal portions of the axon give off several beaded collaterals that arborize primarily in the vicinity of the cell. Class II neurons are smaller, spinesparse cells that are found in all nuclei of the basolateral amygdala but are greatly outnumbered by class I neurons. Axons branch and give off beaded collaterals which form a moderate to dense arborization within the dendritic field of the cell. Class II neurons exhibit considerable morphologic variability including one subtype that resembles the chandelier cell of the cerebral cortex. Varicosities (1.0‐1.5 μm swellings) found along the axonal collaterals of these amygdaloid chandelier cells do not have a uniform distribution but tend to be aggregated. Segments of the collaterals displaying such clustered varicosities sometimes form nest‐like entanglements. Clusters of varicosities have been observed forming multiple contacts with initial segments of class I axons. Class III neurons are neurogliaform cells which have many short, varicose dendritic branches that contact dendrites of class I neurons. Only the initial portions of their axons were impregnated. This study indicates that many of the cell types seen in the generalized, metatherian opossum are similar to those described in more specialized, placental mammals. This is the first description of amygdaloid chandelier cells and their contacts with the spiny initial segments of class I projection neurons.
Changes in nuclear shape and mitochondrial structure do not accompany the loss of division potential in human fibroblasts in vitro
Authors: Pool Thomas B. , Heitman Teri O. , Buck Marilyn A. 
Published: February 2005

AbstractPrevious studies on ultrastructural changes that occur in cultured human fibroblasts during their in vitro life‐span indicate that “senescent” cells characteristically possess structurally altered mitochondia, highly lobed nuclei, and an abundance of secondary lysosomes when compared to early passage cells. In the present study, we demonstrate that improper preparative methods can induce altered mitochondrial morphology in preparations of both IMR‐90 and HF730A fibroblasts, regardless of passage level. We also show that nuclei of both living and fixed IMR‐90 fibroblasts are ovoid in shape, not lobulate, in well‐spread cells, regardless of either the passage level or the proliferative capacity of the cell. Fibroblasts contain lobulated nuclei only when they have not spread completely on the culture substrate. Lobulations can be induced at any passage level by collagenase/trypsin or trypsin/EDTA treatment prior to fixation, but not by cytochalasin B treatment or by cold temperatures. We conclude that any treatment that affects cytoskeleton‐membrane‐culture substrate interactions will induce this aberrant nuclear morphology, but that this is not indicative of “senescence” and does not relate to proliferative decline.