Search Results
Results 451 - 500 of 2394
< 5 6 7 8 9 10 11 12 13 14 15 >
Liu Yi-Xun - - 2005
The present review is a summary of mechanisms of spermatogenesis in primates with emphasis on anti-spermatogenesis of testosterone (T), gossypol, and "testicular heat stress" for development of male contraception, Both FSH and testosterone stimulate all phases of spermatogenesis. FSH is capable of amplifying the population of the differential spermatogonia (B1, ...
Smita Mathew - - 2005
Sertoli cells constitute a permanent feature of the testis lobules in caecilians irrespective of the functional state of the testis. The developing germ cells are intimately associated with the Sertoli cells, which are adherent to the basal lamina, until spermiation. There are irregularly shaped cells in the cores of the ...
Cavaco J E B - - 2005
Little is known about the physiological regulations of spermatogenesis of the African catfish (Clarias gariepinus), a species used as an experimental model for two decades. After a brief introduction to the cystic type of spermatogenesis in fish, the role of androgens and estrogens will be discussed, leading to a conclusion ...
Yu Jian-Jun - - 2005
This study examines the hypothesis that varicocele would impair the testicular expression of cAMP response element modulator (CREM) in experimental rats. Thirty (30) rats were selected at random, of 20 were operated as varicocele's group; of 10 were for sham-operation as controlled group, testes were removed, fixed and stained in ...
Holsberger Denise R - - 2005
Thyroid hormone inhibits neonatal Sertoli cell proliferation and recent results have shown that thyroid hormone upregulates cyclin-dependent kinase inhibitors (CDKIs) p27Kip1 and p21Cip1 (also known as CDKN1B and CDKN1A, respectively) in neonatal Sertoli cells. This suggests that these CDKIs, which negatively regulate the cell cycle, could be critical in Sertoli ...
Ehmcke Jens J University of Pittsburgh School of Medicine, Center for Research in Reproductive Physiology, Department of Cell Biology and Physiology, PA 15261, - - 2005
Spermatogonial expansion in man and non-human primates has been studied for decades. Controversy persists about the cell type representing the testicular stem cell and the exact kinetics of spermatogonial proliferation. We recently determined the starting point of spermatogenesis and proposed a model for clonal expansion of spermatogonia in adult macaques. ...
Farias J G - - 2005
In order to evaluate the effects of the exposition to continuous chronic hypobaric hypoxia (CCHH) and intermittent chronic hypobaric hypoxia (ICHH) on testis histology and on oxidative metabolism of spermatogenic cells (SC), male rats were exposed to a 4600-m simulated altitude (PO2: 89.6 mmHg). After 60 days, ICHH and CCHH ...
Meachem Sarah J - - 2005
The hormones that regulate spermatogonial development are ill defined, in part due to lack of appropriate experimental models. The photoinhibited hamster model provides a rich source of spermatogonia, thus making it an ideal model to study their control. This study aimed to assess the effects of FSH, in the absence ...
França Luiz R - - 2005
Starting from the period of testis differentiation, the Sertoli cell plays a pivotal role in the development of a functional testis. FSH is the major mitotic factor for Sertoli cells. Because the supporting capacity of Sertoli cells is relatively fixed for each species, their total number per testis, established just ...
Chaudhary Jaideep - - 2005
Prior to puberty the Sertoli cells undergo active cell proliferation, and at the onset of puberty they become a terminally differentiated postmitotic cell population that support spermatogenesis. The molecular mechanisms involved in the postmitotic block of pubertal and adult Sertoli cells are unknown. The four known helix-loop-helix ID proteins (i.e., ...
Lai K P - - 2005
Among different mammalian tissues, testis is found to be one of the most sensitive organs to TCDD exposure. In this study, primary Sertoli cell culture was established. The purity of the cultured cells was verified using 3beta-hydroxysteroid dehydrogenase, alkaline phosphatase as well as testosterone induction assays. Effects of TCDD in ...
Shamekh R - - 2005
Transplanting cells across species (xenotransplantation) for the treatment of Parkinson's disease has been considered an option to alleviate ethical concerns and shortage of tissues. However, using this approach leads to decreased cell survival; the xenografted cells are often rejected. Sertoli cells (SCs) are testis-derived cells that provide immunological protection to ...
Loukil L Hadjkacem - - 2005
Our purpose was to evaluate cellular androgen receptor (AR) distribution and intensity of immunostaining in the human azoospermic testis. Thirty six biopsy specimens from azoospermic men were immunostained, using a monoclonal antibody of human AR. The localization and the intensity of AR immunostaining was evaluated in Sertoli Cell Only (SCO) ...
Stewart Jane - - 2005
Inhibin B is a glycoprotein produced predominantly by Sertoli cells which regulates pituitary FSH release by a negative feedback loop. The regulation of inhibin B is complex with changes in the pattern of secretion occurring during development, and many factors such as FSH, testosterone, Sertoli cell proliferation and germ cell ...
Kotula-Balak M - - 2005
A broad expression of aromatase and estrogen receptors (ERs) in the testis suggests an important role for estrogens in regulating testicular cell function and reproductive events. The aim of the present study was to show whether Leydig cells in vitro isolated from cryptorchid testes of two inbred strains of mice, ...
Lui Wing Yee - - 2005
The movement of developing germ cells across the seminiferous epithelium during spermatogenesis involves extensive adherens junction (AJ) restructuring between Sertoli cells, as well as between Sertoli and germ cells. In this report, we show that the intricate interactions between Cdc42 (a Rho family protein of Mr approximately 23 kDa originally ...
Aladakatti R H - - 2005
Azadirachta indica leaf powder, 0.05 mg testosterone, or combined leaf powder + testosterone was administered for 48 days to different groups of 3-month-old albino rats. Twenty-four hours after the final dose, the treated animals received mild ether anesthesia and the testes were dissected out and processed for light and electron ...
McClusky L M - - 2005
To understand the processes involved in the spatial and temporal maturation of testicular cells in Squalus acanthias, we used standard morphometry, proliferating-cell nuclear antigen (PCNA) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) immunohistochemistry. Except for immature spermatocysts (germinal zone, GZ; early-stage pre-meiotic, E-PrM), the number of cysts in all ...
Bar-Shira Maymon Batia - - 2005
The current study identified for the first time calretinin expression in abnormal Sertoli cells of azoospermic men who underwent testicular biopsy for sperm recovery and application of the retrieved sperm by in vitro fertilization techniques. Testicular biopsies with various spermatogenic impairments were evaluated immunohistochemically for the expression of the calretinin ...
Doepner Richard F G - - 2005
Gamma-aminobutyric acid (GABA) is an emerging signalling molecule in endocrine organs, since it is produced by endocrine cells and acts via GABA(A) receptors in a paracrine/autocrine fashion. Testicular Leydig cells are producers and targets for GABA. These cells express GABA(A) receptor subunits and in the murine Leydig cell line TM3 ...
Boekelheide Kim - - 2005
Azoospermia and long-lasting testicular atrophy are common adverse consequences of cancer treatment. Chemotherapeutic agents may disrupt spermatogenesis by targeting various testicular cell types (Leydig cells, Sertoli cells, and germ cells) and by activating numerous molecular pathways involved in germ cell life-and-death decision making. Genetically modified animal models with deficiencies in ...
Aguilera-Merlo Claudia - - 2005
Little is known about morphological changes in the epididymis in relation to the natural photoperiod or their influence on sperm maturation. The viscacha is a seasonal rodent living in the Southern Hemisphere. The adult males exhibit an annual reproductive cycle with periods of maximum gonadal activity and gonadal regression. In ...
Wolski Katja M - - 2005
Cortactin, an actin binding protein, has been associated with Sertoli cell ectoplasmic specializations in vivo, based on its immunolocalization around the heads of elongated spermatids, but not previously identified in isolated Sertoli cells. In an in vitro model of Sertoli cell-spermatid binding, cortactin was identified around debris and dead germ ...
Miura C - - 2005
Endocrine disrupters have been recognized to interfere with endocrine systems that regulate reproduction, for example, by mimicking or inhibiting the action of endogenous sex steroid hormones including estradiol-17beta (E2). In the present study, we examined the effect of an endocrine disrupter, para-nonylphenol (p-NP) on spermatogenesis, and compared it with the ...
Park Susan Y - - 2005
The embryonic gonad is undifferentiated in males and females until a critical stage when the sex chromosomes dictate its development as a testis or ovary. This binary developmental process provides a unique opportunity to delineate the molecular pathways that lead to distinctly different tissues. The testis comprises three main cell ...
Yang Zheng-Wei - - 2004
AIM: To evaluate the key lesions in spermatogenesis suppressed partially by testosterone undecanoate (TU) treatment. METHODS: Adult male SD rats were treated with vehicle or TU (19 mg/kg) injection (i.m.) every 15 days for 130 days. The numbers of all types of cells (nuclei) in the seminiferous tubules and the ...
Davidoff Michail S - - 2004
The cells responsible for production of the male sex hormone testosterone, the Leydig cells of the testis, are post-mitotic cells with neuroendocrine characteristics. Their origin during ontogeny and regeneration processes is still a matter of debate. Here, we show that cells of testicular blood vessels, namely vascular smooth muscle cells ...
Khan Uniza W - - 2005
The present in vitro study, for the first time, demonstrates the endocrine as well as paracrine control of Leydig cell steroidogenesis and proliferation in the wall lizard Hemidactylus flaviviridis. Unlike mammals, Leydig cell activity in the wall lizard seems to be directly controlled by ovine follicle-stimulating hormone (FSH)-like molecule, since ...
Konrad Lutz - - 2005
A new immortal Sertoli cell line from pubertal rat testis was established and characterized. We have generated the clonal line SCIT-C8 expressing established markers for Sertoli cells (SC) like transferrin, clusterin and steel factor/stem cell factor (SCF). Additionally, the immortalized cells express afadin, a protein which is a member of ...
Chaves-Pozo Elena - - 2005
The gilthead seabream is a protandrous hermaphrodite seasonal breeding teleost with a bisexual gonad that offers an interesting model for studying the testicular regression process that occurs in both seasonal testicular involution and sex change. Insofar as fish reproduction is concerned, little is known about cell renewal and elimination during ...
Mahood I Kim - - 2005
Fetal exposure of male rats to di (n-butyl) phthalate (DBP) induces testicular changes remarkably similar to testicular dysgenesis syndrome in humans; these include induction of focal areas of dysgenetic tubules in otherwise normal testes. In searching for the fetal origins of the latter, we used image analysis to show that ...
Park Mi-Rung - - 2004
In this investigation, 22 cloned male piglets were obtained by male fetal fibroblast-cell-derived nuclear transfer. Eighteen of the cloned animals died. The two cell lines did not differ significantly with regard to efficiency of live piglet production. The gross anatomy of the testes of male piglets that died was normal. ...
Sato Takeshi - - 2004
Usp9x, an X-linked deubiquitylating enzyme, is stage dependently expressed in the supporting cells (i.e. Sertoli cells and granulosa cells) and germ cells during mouse gametogenesis. Af-6, a cell junction protein, has been identified as a substrate of Usp9x, suggesting a possible association between Usp9x and Af-6 in spermatogenesis and oogenesis. ...
Hayakawa Daisuke - - 2004
The testes from 15 adult male Hokkaido Sika deer (Cervus nippon yesoensis) were collected during the rutting season (October and November). We investigated the localization of 4 kinds of steroidogenic enzymes (P450scc, 3betaHSD, P450c17 and P450arom) immunohistochemically in these testicular samples. The specific immunoreactivities to these enzymes were detected only ...
Segatelli Tânia M - - 2004
The gerbil (Meriones unguiculatus) is a rodent native of the arid regions of Mongolia and China. Because the gerbil can be easily bred in laboratory conditions, this species has been largely used as an experimental model in biomedical research. However, there is still little information concerning the testis structure and ...
Show Matthew D - - 2004
The receptors for the steroid hormone testosterone and the peptide hormone follicle-stimulating hormone are localized to the somatic Sertoli cell in the seminiferous epithelium. In the rat, prolonged gonadotrophic hormone withdrawal has been shown to result in substantial germ cell apoptosis. Previous studies have shown that, coincident with the loss ...
Schön J - - 2004
Roe deer (Capreolus capreolus) is a seasonal breeder showing extreme changes in spermatogenic activity. It is an excellent model to study the regulation of testicular activation and regression by endocrine signals and paracrine effectors such as growth factors. Previous studies on FGF-1 mRNA showed a special seasonal expression pattern in ...
d'Istria Michela - - 2004
This study was conducted to verify the effect(s) of melatonin treatment on frog Leydig cells. Morphological observation after melatonin treatment indicates that many frog Leydig cells show degenerative changes (i.e. heterochromatic nuclei, loss of cellular adhesion) while in adjacent germinal tubules several Sertoli cells show heterochromatic nuclei, confirming the presence ...
Porawski M - - 2004
Acid phosphatase (AcP) activity was investigated in the testes of two species of teleosts in two seasons: summer and winter. AcP activity was detected in Sertoli cells from tilapia (Oreochromis niloticus) only during the nonreproductive period of its annual cycle, corresponding to the winter months. In kingfish (Odonthestes perugiae), the ...
Shah Chirag - - 2005
Progesterone and progesterone receptors (PR) play a crucial role in female reproduction, but their roles in male reproductive physiology are largely unknown. Our previous studies demonstrated the presence of a specific membrane-bound PR in mature human spermatozoa that is known to regulate important sperm functions. The present study was undertaken ...
de Kretser D M - - 2004
The role of the inhibins, activins and follistatins in testicular function are being more clearly defined following studies describing the cellular localisation of these proteins to the testis and the availability of specific assay systems enabling measurement of these proteins. Taken together with the results of targetted gene inactivation experiments, ...
Sekido Ryohei R Division of Developmental Genetics, MRC National Institute for Medical Research, London NW7 1AA, - - 2004
The Y chromosome gene Sry encodes a transcription factor required to initiate testis development. The related autosomal gene Sox9 is up-regulated shortly after the onset of Sry transcription and is thought essential for the differentiation of Sertoli cells. The lineage that gives rise to Sertoli cells has its origins within ...
Anbalagan M - - 2004
In rats, during postnatal Leydig cell development, the progenitor Leydig cells (PLC) proliferate actively during days 14-21 of postnatal life. Luteinizing hormone (LH) is known to stimulate Leydig cell proliferation and oestradiol 17beta inhibits this process. In order to identify the molecules involved in Leydig cell proliferation, differentially expressed genes ...
Khan Umar Ali - - 2004
BACKGROUND: The Leydig cell is the source of the male sex steroids, or androgens, which are essential for the maintenance of the male phenotype, the male gonads. and spermatogenesis. It has been reported that patients taking beta-blockers experience sexual dysfunction. The purpose of this study was to explore the direct ...
Puglisi Rossella - - 2004
AIM: The aim of this study was to determine the action of bone morphogenetic proteins (BMPs) on testicular cell proliferation during early postnatal life, a definite developmental time at which crucial changes in germ cell and Sertoli cell maturation occur. METHODS: We investigated the effect of BMP2 and BMP7, two ...
Fujisawa Masahiko - - 2004
The Prnp (prion protein) gene, which encodes a soluble protein anchored to the cell surface by glycosylphosphatidylinositol (GPI), might be involved in cell-to-cell interaction. The expression of Prnp is strongly observed not only in the brain, but also in non-neuronal tissues. In order to examine the Prnp expression sites in ...
D'Abrizio Piera - - 2004
Over the past few years, a number of experimental evidences suggested the involvement of Fas Ligand (FasL) expressing Sertoli cells to induce apoptosis of Fas bearing germ cells. However, the FasL expression during testicular development and its cell specific localization within the testis is still a matter of debate. In ...
Zanghì A - - 2004
A 30-year-old Standardbred stallion was examined for unilateral scrotal swelling. Physical and ultrasound examinations revealed a painless enlarged left testis with a non-homogeneous echogenicity, when compared with the controlateral testis. The stallion underwent left unilateral orchiectomy. Grossly, the excised testis was irregularly enlarged (12 x 9 x 9 cm; weight: ...
Gliki Georgia - - 2004
During spermatogenesis in the mammalian testis, stem cells (spermatogonia) differentiate into spermatocytes, which subsequently undergo two consecutive meiotic divisions to give rise to haploid spermatids. These cells are initially round but progressively elongate, condense their nuclei, acquire flagellar and acrosomal structures, and shed a significant amount of their cytoplasm to ...
Ehmcke Jens - - 2005
The present study examines the existence of clonogenic patterns in the proliferation and differentiation of spermatogonial stem cells in two species of non-human primates, the marmoset and the rhesus monkey. We developed a novel approach to detect proliferating spermatogonial clones in whole mounts of seminiferous tubules. Dual fluorescence labeling of ...
< 5 6 7 8 9 10 11 12 13 14 15 >