摘要:

AbstractThe formation of malondialdehyde (MDA), a product of lipid peroxidation (LPO), was measured in human spermatozoa from 27 subjects with normal sperm characteristics. Peroxidation of lipids in washed spermatozoa was induced by catalytic amounts of ferrous ions and ascorbate and malondiaidehyde dctermint‐d by thiobarbituric method. MDA formation varied considerably from one sample to another. The studied population showed a strong correlation between lipid peroxidation potential (amount of MDA formed by 108spermatozoa after 1 hour of incubation) and 1) initial motility r = −0.623,P= 0.001; and 2) morphologic abnormalities of the midpiece r = 0.405,P= 0.05. These results suggest that poor motility is linked with membrane fragility and that spermatozoa with midpiece abnormalities probably have membrane and/or cytoplasmic antiperoxidant system defects. Because LPO potential is related to the two most important characteristics of fertility, it seems possible that it has the potential to become a good biochemical index of semen qual

ISSN:0148-7280    

DOI:10.1002/mrd.1120240202

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe process of human male pronuclear formation was studied using an experimental model based on in vitro inseminated human zona‐free eggs prepared from oocytes that failed to fertilize in a clinical in vitro fertilization program. The main ultrastructural changes in penetrated sperm nuclei transforming into pronuclei were used to define four stages of pronuclear development. The first two stages, representing partial (Stage 1) and total (Stage 2) sperm chromatin decondensation, appeared as early as 1 hr after mixing of gametes. This rapid initial phase was followed by a more lengthy array of events leading to transformation of decondensed sperm nuclei into fully developed male pronuclei (Stages 3 and 4). Stage 3 was characterized by reformation of the nuclear envelope, reorganization of chromatin, and the assembly of nuclcolar precursors. It was not completed until 12 hr after in vitro insemination when fully developed male pronuclei (Stage 4) were first observed. In some eggs pronuclei did not reach Stage 4 at all. The results of this study provide a morphological background for further research into molecular aspects of human male pronuclear development and its regulatio

ISSN:0148-7280    

DOI:10.1002/mrd.1120240203

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn order to characterize trout Sertoli cells and germ cells obtained after testis dissociation and cell separation, we have studied their morphology, ultrastructure, survival, and ability to express differentiated activities in primary cultures. After dissociation, the fine structure of Sertoli cells does not differ from that observed in situ and only minor changes are shown for at least 13 days. Until they are flattened in a monolayer, they keep the ability to retain germ cells on their surface. When flattened, some of them are able to divide. At the opposite of meiotic germ cells, spermatogonia can develop independently of Sertoli cells. They are able to proliferate during at least 10 days. Spermatocytes and spermatids are obtained as single cells and multinucleated giant cells (symplasts). In the absence of somatic cells, their maximal viability is approximately 5 days, whereas spermatocytes adhering to Sertoli cells can survive at least 10–12 days, provided trout lipoproteins are present. Spermatocytes are able to differentiate to spermatids, although this process is impaired for some ceils. The adhesion of spermatogonia and spermatocytes to Sertoli cells is specific, mediated by desmosome‐like junctions and favored by lipoproteins. These data are compared to what is known in mammals and in amphibi

ISSN:0148-7280    

DOI:10.1002/mrd.1120240204

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

年代:1989

数据来源: WILEY

摘要:

AbstractProtein phosphorylation activity, chromosome segregation, and cortical granule exocytosis (CGE) have been studied in mouse eggs activated parthenogeneticaliy by specific PKC stimulators such as 4β‐phorbol 12‐myristate 13‐acetate (PMA) and l‐oleyl‐2‐acetylglycerol (OAG), or by agents inducing an immediate increase in cytosolic calcium concentration ([Ca2+]i) such as ethanol and Ca‐ionophore A23187. When protein phosphorylation activity of mouse eggs was analyzed 10 min after different activation treatments, the phosphorylation of a 32 kDa polypeptide was a feature common to all different parthenogenetic agents used. The appearance of such labeling was independent of an increasing [Ca2+]i, as indicated by direct measurements of i) cytosolic Ca2+concentration with fura‐2 and 2) exogenous Ca2+entrance into activated eggs. Emission of the second polar body was blocked in PMA‐elicited partheno‐genones, whereas it was apparently normal in OAG‐treated eggs, unless the eggs were continuously exposed to OAG. CGE was almost immediate in ethanol‐activated eggs, but in PMA‐treated cells, it occurred significantly later, with a timing corresponding to that found for the appearance of sustained Ca2+oscillations in this system. Here, we propose that in mammalian eggs 1) PKC stimulation represents an early regulatory step in egg activation; 2) this kinase activity is turned off before the second meiotic cleavage; and 3) cytosolic free Ca2+rise is es

ISSN:0148-7280    

DOI:10.1002/mrd.1120240205

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

年代:1989

数据来源: WILEY

摘要:

AbstractCatalase activity was determined in human semen by measuring the oxygen burst with a Clark electrode, after H2O2addition. Significant catalase activities (mean ± SD) were found in migrated, motile spermatozoa (44 ± 17 nmoles O2/min/108cells) and in seminal plasma of normozoospermic men (129 ± 59 nmoles O2/min/ml). It has been demonstrated that seminal catalase originated from prostate; however, its activity was not correlated with the usual prostatic markers (such as citric acid and zinc). Our data suggest a multiglandular function secreted by this organ. The catalase activities measured in seminal samples from asthenozo‐ospermic, infertile men were found lower than those from normozoospermic subjects. The understanding of the relative contribution of the different enzyme systems against O2toxicity (superoxide dismutase, catalase, glutathione peroxidase) seem to be a priority area of research to understand disturbances of sperm func

ISSN:0148-7280    

DOI:10.1002/mrd.1120240206

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

年代:1989

数据来源: WILEY

摘要:

AbstractBovine cumulus oocyte complexes (COCs) as used for in vitro maturation and fertilization can be classified into different categories by light microscopical inspection. We have distinguished four categories based on compactness and transparency of the cumulus investment and homogeneity and transparency of the ooplasm. The four categories were studied for their morphological characteristics at the ultrastructural level and for their developing capacity in an in vitro maturation system. In categories 1 and 2 oocytes, organelles were evenly distributed. In categories 3 and 4, oocytes organelles were clustered and the distribution of the organelles mimicked the characteristics of oocytes during final maturation. Cumulus cell process endings penetrated the cortex of the oocyte or were located superficial to the cortex of the oocyte. In category 1 oocytes, most of the process endings penetrated the cortex. In category 4 oocytes, most of the process endings did not penetrate. In categories 2 and 3 oocytes, both forms of process endings did occur.After in vitro maturation, only category 4 oocytes showed a decreased developing capacity. Categories 1–3 oocytes showed equal developing capacity in an in vitro maturation syste

ISSN:0148-7280    

DOI:10.1002/mrd.1120240207

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

年代:1989

数据来源: WILEY

摘要:

AbstractIt has been suggested that the abnormal maturation of the human oocyte during fertilization in vitro may result in chromosome imbalance and, induce embryonic loss. Using a mouse model, we have studied the influence of the degree of oocyte maturation (either immaturity or overmaturity) on the chromosome characteristics of embryos at the first‐cleavage division. Immature oocytes were obtained 2–3 h or 3–4 h before the expected ovulation time (b.o.). Overmaturation was induced by aging the newly ovulated oocytes in vitro for 3,6, and 12 h. Our results show a significant decrease in the fertilization rate in the immature groups (65.53% at 2–3 h b.o. and 16.59% at 3–4 h b.o. vs. 78.22% at control) and after 12 h of in vitro aging (69.39%), while a significant increase of this parameter was found at 3 h of aging (82.59%) as compared to the other groups. No significant differences were found in the occurrence of aneup'.oidy or hypcrhaploidy in embryos obtained from immature, newly ovulated, and overmature oocytes. Finally, an increased incidence of polyploidy was detected in immature, 2–3 h b.o. (31.20%), and overmature, 3 h (23.04%) and 6 h (31.61%), groups as compared to the control gro

ISSN:0148-7280    

DOI:10.1002/mrd.1120240208

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

年代:1989

数据来源: WILEY

摘要:

AbstractOstrea edulisspawns spermatozeugmata, each composed of radially arrayed sperm cells attached by an extracellular matrix (ECM) to a core of acellular vesicles. The acellular vesicles arc formed from excess nuclear and plasma membranes produced during spermatid condensation, and the ECM is topologically restricted to the interstices between acellular vesicles and sperm heads, being absent from the flagellar surface. When released into seawater, spermatozeugmata retain their structural integrity for varying periods (up to 24 hours) and become demersally distributed in still water. The flagella activate, initially beating in a non‐synchronized, languid manner; however, both the tempo and amplitude of the flagellar action gradually increase to resemble that of typical ‘primitive’ sperm once the cells are released from the spermatozeugma. This increase in flagellar activity and subsequent gamete release coincide with an erosion of the ECM and suggest that the ECM may modulate sperm motility in addition to adhering the cells to the spermatozeugma. Sperm are capable of fertilizing eggs only after dissociating from the spermatozeugma. The net effect of spermatozeugma formation inOstrea edulismay be the retention of viable sperm in high concentrations at the benthic/ water column interface for prolonged periods after spawning, at least in low current regimes. UnfertilizedO. eduliseggs are also concentrated at this location, in the inhalent chambers of female oysters. Spermatozeugmata are entrained by the inhalent current of females and carried into the brood chamber where fertilization occurs. TheOstrea edulisspermatozeugma likely functions as an efficient sperm transfer mechanism if two conditions are met: 1) eggs are retained as broods within benthic females, 2) egg masses are at intermediate distances from spawning

ISSN:0148-7280    

DOI:10.1002/mrd.1120240209

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

年代:1989

数据来源: WILEY

摘要:

AbstractEpididymal transit is involved in the acquisition of fertilizing ability by mammalian spermato‐zoa. The epididymis is implicated in the addition and/or modification of sperm surface proteins functionally involved in the processes leading to fertilization. In order to characterize these sperm components, we have studied the modifications of sperm membrane proteins during epididymal maturation. Hamster spermatozoa were collected from the caput, corpus, and proximal and distal cauda of the epididymis and submitted to a continuous Percoll gradient centrifugation. Independently of their epididymal origin, the spermatozoa were distributed into two bands of buoyant densities of 1,045 and 1,088 on the gradient. However, the proportion of more dense spermatozoa increased progressively along the epididymis. This proportion is 87–fold higher in the distal cauda compared to the caput. SDS‐PAGE electrophoresis demonstrated that although they originate from different regions of the epididymis, spermatozoa of the same density exhibited similar membrane protein patterns. In contrast, the electrophoretic patterns of spermatozoa with densities of 1,045 and 1,088 were very different One of these differences involves a 26 kD protein that is implicated in zona pellucida recognition (Sullivan and Bleau,Gamete Res 12.101–116,1985). This protein is present in dense sperm obtained from all regions of the epididymis but is absent in spermatozoa of low density. If we consider that this 26 kD protein is a ‘marker’ of surface changes occurring during sperm maturation, we can hypothesize that in the proximal segments of the epididymis a certain proportion of spermatozoa are indeed mature but that this proportion increases considerably along the

ISSN:0148-7280    

DOI:10.1002/mrd.1120240210

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

年代:1989

数据来源: WILEY

摘要:

AbstractXenopus laevissperm plasma membrane ultrastructure has been studied by means of freeze‐fracture, deep‐etching, and lectin‐gold binding.Xenopusspermatozoa differ from those of other species in that their plasma membrane does not exhibit topographical domains. In fact, no geometric arrangement or characteristic array of particles is present on fractured plasma membrane. Fractures rarely occur in acrosomal or nuclear membranes. Wheat germ agglutinin receptors are distributed homogeneously, on the plasma membrane of the sperm head and

ISSN:0148-7280    

DOI:10.1002/mrd.1120240211

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

年代:1989

数据来源: WILEY