摘要:

AbstractThe intracellular and cell surface localization of an embryonic glycoprotein antigen (BL) has been investigated in preimplantation mouse embryos using ultrastructural immunocytochemistry. Several interesting points have emerged: (1) BL antigens are exclusively localized subjacent to the plasma membrane in the cortical region of cells, whereas antigens detected by a control antibody against mouse L cells are distributed throughout the embryo. (2) The distribution of BL antigens is polarized beginning with the first cleavage, with expression confined to the cortex underlying the free or apical portions of cells. No antigen is present underlying regions of cell contact. (3) Although embryonic synthesis of BL antigens does not begin until the two‐cell stage, BL antigens are observed in unfertilized eggs, a fact verified by immunoblottin

ISSN:0148-7280    

DOI:10.1002/mrd.1120120402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractPrevious reports indicate that glycosaminoglycans (GAGs) would enhance the occurrence of acrosome reactions in sperm in vitro, but continuous exposure of those sperm to seminal plasma prevented a significant incidence of acrosome reactions. This study was designed to evaluate the interaction of GAGs and seminal plasma to promote acrosome reactions in bull sperm in vitro. Epididymal sperm required 22 hr to exhibit acrosome reactions in response to GAGs whereas only 9 hr were needed to achieve the same effect with washed ejaculated sperm. Exposure of epididymal sperm to seminal plasma for 20 min shortened the time for induction of the acrosome reaction to 9 hr. Scatchard analyses of displacement data suggested an alteration in the binding affinity of3H‐heparin to epididymal sperm membrane following the short‐term exposure to seminal plasma. High doses (250 and 500 μg/ml) of heparin, heparan sulfate, and chondroitin‐4‐sulfate were without effect, but doses<100 μg/ml were stimulatory in terms of enhancing acrosome reactions. Compositional studies with seminal plasma revealed a total GAG content of 1.6 mg/ml, proportioned as 61.6% chondroitin sulfates, 17.6% heparin‐like material, 0.3% hyaluronic acid, and 20.5% undetermined GAG. It is proposed that seminal plasma can alter the ability of sperm to respond to GAGs, and the high concentrations of GAGs endogenous to seminal plasma may prevent premature initiation of the membrane perturbations necessary for the acroso

ISSN:0148-7280    

DOI:10.1002/mrd.1120120403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe mechanisms involved in the impaired spermatogenesis of male goldfinch x canary hybrids were investigated by transmission electron microscopy and compared with spermatogenesis in the testes of the parent species.In the parent species the testes were of normal structure, with the only unusual observation being that the Sertoli cells were variable in cytoplasmic electron density. In hybrid birds the Sertoli cells were either electron dense or electron lucent with respect to both nucleus and cytoplasm.In the hybrids examined in this study, no spermatozoa were produced. Spermatogenic stages were arrested without formation of synaptonemal complexes. Centrioles were abnormally arranged in both somatic and germ cells. When they moved away from the basement lamina the germ cells degenerated and were phagocytosed. No focal tight junctions were present between Sertoli cells overlying what would normally have been the basal compartment of the tubule. The basement lamina was unusually thickened, peritubular cells were abnormal in structure, and numerous plasma cells were present in the interstitial tissue.The observations reported here suggest that there was an immunological basis for degeneration of germ cells in the hybrid testis.

ISSN:0148-7280    

DOI:10.1002/mrd.1120120404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractParacrystalline inclusions, readily visible with light microscopy, were found to be present in ovarian oocytes (beginning with unilaminar follicles), ovulated ova, and preimplantation embryos of the Chinese hamster. These inclusions appeared to be aggregates of finer filamentous structures visible only with electron microscopy. The use of various histochemical techniques suggested that the paracrystals were composed of protein with little or no lipid associated with them. Autoradiographic studies using3H‐uridine and enzymatic studies did not support the hypothesis that the paracrystalline inclusions were composed of RNA masked by a crystalline protein lattic

ISSN:0148-7280    

DOI:10.1002/mrd.1120120405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe fine structure of pronuclear ova (monospermy and polyspermy) and one‐cell embryos has been investigated in our IVF programme. Sixteen oocytes were collected at laparoscopy after appropriate hormonal stimulation and were matured and fertilized in vitro by methods that have given rise to normal pregnancies.Pronuclear ova showing monospermic fertilization had two vesicular pronuclei surrounded by aggregations of cellular organelles. The male pronucleus was closely associated with a sperm axoneme, while the female pronucleus was dismantling its envelope and condensing its chromatin ahead of its counterpart in late pronuclear ova. Each pronucleus had dispersed chromatin, dense compact nucleoli, and intranuclear annulate lamellae. Smooth endoplasmic reticulum, annulate lamellae, Golgi complexes, and mitochondria formed a conspicuous part of the perinuclear ooplasm. The one‐cell embryos were either in syngamy or in the process of undergoing first cleavage. Positive evidence of cortical granule release and second polar bodies were detected in the perivitelline space. A block to polyspermy seemed to operate at the level of the inner zona.Dispermic and polyspermic ova had 3–16 pronuclei resembling those of monospermic ova and had sperm tails in the ooplasm. Sperm were also seen penetrating the inner zona and were occasionally found in the perivitelline space. Incomplete cortical granule release and early signs of cytoplasmic fragmentation were noted in polyspermic ova.Both normal and abnormal features of these ova are reported and compared with pronuclear structure in vivo and in

ISSN:0148-7280    

DOI:10.1002/mrd.1120120406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe methylation of proteins and phospholipids has been demonstrated in mammalian sperm. The role of these methylation reactions in the regulation of sperm motility is, however, unclear. A combination of agents [adenosine, L‐homocysteine and erythro‐9‐(2‐hydroxyl‐3‐nonyl) adenine (EHNA)] known to increase the level of S‐adenosylhomocysteine (AdoHcy), a competitive inhibitor of S‐adenosylmethionine (AdoMet)‐mediated methylations, has been shown to inhibit rabbit sperm motility. The level of AdoHcy in response to these agents has, however, not been measured. Therefore, enzymatic protein carboxylmethylation (PCM) and the consequences of its inhibition by elevated intrasperm AdoHcy levels on motility were studied using bovine sperm. Incubation of bovine cauda epididymal sperm with L‐[methyl‐3H]methionine resulted in a linear increase in PCM for up to 2 h. Treatment of sperm with adenosine (0.5 mM), L‐homocysteine (0.5 mM), and EHNA (0.25 mM) produced a dramatic increase in AdoHcy levels after 15 min and a 97% inhibition of PCM after 0.5 h, followed by an inhibition of sperm motility (58% and 97%) after 1 and 2 h. Similar but less marked results were obtained with L‐homocysteine (0.5 mM) alone. Individually, cycloleucine (20 mM), an inhibitor of AdoMet synthetase, and adenosine (0.5 mM) also inhibited PCM (87% and 70%, respectively) after 2 h but had no effect on sperm motility or AdoHcy levels. These studies show for the first time that agents that elevate AdoHcy levels inhibit sperm motility. This, however, leaves open the question of whether protein carboxylmethylation or other methyl transfer reactions, eg, involving phospholipid, might be critical to motility inhibition by AdoHcy. Thus, the mechanism by which AdoHcy inhibits sperm

ISSN:0148-7280    

DOI:10.1002/mrd.1120120407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractQuantitative fluorescence microscopy is used to compare the binding of the fluorescent, 7‐amino derivative of actinomycin D to a sonication resistant fraction of late‐step mouse spermatids and sperm isolated from three regions of the epididymis. Staining conditions are described that optimize 7‐AMD binding to air‐dried smears of these cells and permit quantitative analyses of 7‐AMD binding to sperm chromatin at the single cell level. These studies show that the step 12–16 spermatid undergoes an 8–10‐fold reduction in 7‐AMD binding as it completes differentiation in the testis and progresses through the epididymis. The first 2–3‐fold reduction in binding, associated with biochemical changes in chromatin structure brought about during spermatid differentiation, occurs gradually and is complete by the time the sperm reaches the caput epididymis. An additional four‐fold reduction is observed as the sperm passes through the corpus. This final alteration, which occurs in a single concerted step, may be reversed by dithiothreitol treatment and appears to be effected through the formation of a final, small group of sperm nuclear prote

ISSN:0148-7280    

DOI:10.1002/mrd.1120120408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0148-7280    

DOI:10.1002/mrd.1120120409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0148-7280    

DOI:10.1002/mrd.1120120401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY