摘要:

AbstractIncorporation of [32P]‐phosphate into proteins was enhanced when Sabellaria oocytes were stimulated with specific protease to continue from prophase I block to metaphase I block. The rate of incorporation was increased 50 fold between onset of treatment and germinal vesicle breakdown (GVB). The same result was obtained when release from prophase block involved fertilization, or activation with ionophore A 23187. In all cases, meiosis was associated with phosphorylation of an 18,000 dalton protein, which is perhaps not labeled in prophase‐blocked oocytes. Phosphorylation of a 38,000–40,000 dalton doublet of membrane proteins, which are among the main phosphorylated proteins in intact oocytes, was also strongly enhanced in vitro in homogenates prepared from oocytes following release from prophase

ISSN:0148-7280    

DOI:10.1002/mrd.1120050202

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

年代:1982

数据来源: WILEY

摘要:

AbstractWe have studied some of the effects of nicotine on sea urchin eggs, spermatozoa, and their interaction using electrical recording techniques and fertilization‐rate experiments. Pretreating eggs with nicotine enhances the fertilization rate, whereas this drug has an inhibitory effect on spermatozoa. Pulse‐treated eggs or eggs fertilized in the presence of nicotine give rise to attenuated step depolarizations, which may be attributed to a decrease in membrane resistance (Rm) of the egg or, in the latter case, to an alteration to the spermatozoon. Concurrently, with the change in the step depolarization there is a reduction in amplitude of the fertilization potential (FP) suggesting that the cortical reaction is in some way altered. Nicotine has no effect on the Rm of fertilized eggs or oocytes, where there are no cortical granules. We suggest that nicotine alters the cortex of sea urchin eggs–possibly by causing a partial dissolution of cortical granules–which renders the eggs more receptive to spermatozoa. The reductions in amplitude of the step depolarization and the FP are consequences of this alt

ISSN:0148-7280    

DOI:10.1002/mrd.1120050203

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe problem of how the successive nucleoproteins enter and leave the nucleus of mammalian spermatids is studied with electron microscopy in thick and thin sections of testis, stained en bloc with the procedure of Thiery and Rambourg [1976], which is able to immobilize small molecules. Staining at different pH values reveals that the stain could demonstrate some spermatidspecific nucleoproteins in elongating nuclei and the spermatozoa‐specific protamines in elongated nuclei of the boar, the ram, and the stallion. The stained substances enter or leave the nuclei at precise steps in spermiogenesis. They follow several ways inside a special apparatus made rigid with the manchette. The apparatus is composed of the endoplasmic reticulum, continuous with the nuclear envelope, and of the nuclear pockets continuous with the nuclear pores. In the stallion and the boar, cytoplasmic granules, surrounded by a double wall of membranes, fuse with the nuclear envelope at the time the protamines enter the nucleu

ISSN:0148-7280    

DOI:10.1002/mrd.1120050204

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe effects of zinc on human sperm motility, fertilizing capacity (as assessed by penetration of human spermatozoa into the zona pellucida‐free hamster oocyte), and nuclear chromatin decondensation were investigated using spermatozoa from four fertile donors. Both sperm motility and the penetration of sperm into zona‐free hamster ova were consistently impaired in media containing 1,000 μM zinc. Spermatozoa from one man were similarly affected at a concentration of 500 μM zinc, but no adverse effects were noted at this zinc concentration in experiments with other donors. Since decreased fertilizing capacity in response to zinc was always accompanied by a significant decline in both the percentage of motile cells and mean swimming speeds, it appears that all of these results reflect a general toxic effect on the cells. At lower concentrations (125–250 μM), zinc had no effect on human sperm motility nor their ability to undergo capacitation and penetrate zona‐free hamster ova in vitro. For some donors, zinc (125–500 μM) stimulated both the attachment of spermatozoa to the hamster vitellus and the incorporation of spermatozoa into the hamster ooplasm. The decondensation of human sperm nuclear chromatin in sodium dodecyl sulfate was largely inhibited when zinc was added to the medium, but no significant changes in nuclear stability were apparent after capacitation in zinc‐free medium. We conclude that zinc, when present in subtoxic concentrations, does not adversely affect the ability of human spermatozoa to undergo capacitation and penetrate zona‐free ham

ISSN:0148-7280    

DOI:10.1002/mrd.1120050205

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn this paper we report on the mechanism of action of bonellin on sea urchin eggs. Bonellin acts in the same way as porphyrins, ie, by causing the crosslinking of membrane proteins and the peroxocompounds formation. A possible role of membrane organization related to cleavage formation is discussed.

ISSN:0148-7280    

DOI:10.1002/mrd.1120050206

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

年代:1982

数据来源: WILEY

摘要:

AbstractDuring maturation in the epididymis, mouse sperm nuclei become difficult to stain with Giemsa and its component basic dyes. Mature sperm from the cauda epididymis can be stained only after DTT treatment. Stainable sperm such as those from the testis accumulate3H NEM when examined by autoradiography, while unstainable sperm do not, indicating a close correlation between the basic dye binding capacity and SH levels in the sperm nuclei. During insemination of zonafree ovarian oocytes with a germinal vesicle (GV), mature sperm nuclei become stainable and capable of binding with3H NEM. At the same time, sperm have established pronase‐resistant contact with the oocyte. Similarly, sperm nuclei become stainable during fertilization when the sperm attachment to the egg becomes pronase resistant. However, these changes occur before sperm chromatin decondensation begins. Therefore, it is suggested that S‐S bonds in sperm nucleoproteins are reduced when the sperm establish a stable contact with the egg plasma membrane, thus reversing sperm maturational changes. The reduction of S‐S bonds may be a prerequisite for sperm chromatin decondens

ISSN:0148-7280    

DOI:10.1002/mrd.1120050207

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

年代:1982

数据来源: WILEY

摘要:

AbstractElectron microscopic analysis of fertilization in the sea urchin, Strongylocentrotus purpuratus, has been carried out in an effort to establish the sequence of events involving dispersion of the paternal chromatin. Subsequent to loss of the nuclear envelope the condensed sperm chromatin begins to disperse under the influence of egg cytoplasmic factors. However, this process does not proceed at a uniform rate as is observed in other species examined to date. Portions of the paternal genome rapidly transform into dispersed chromatin while other adjacent regions disperse at a reduced rate. This variation in the time sequence of dissociation of the paternally derived chromosomes results in a reticulum of electron lucent and electron dense chromatin within the developing male pronucleus. As the paternally derived chromatin is dispersing and migrating centrad, membranous vesicles of maternal origin become aligned along the peripheral aspect of the chromatin. Deposition of a continuous bilaminar nuclear envelope around the dispersing sperm chromatin results in the formation of the definitive male pronucleus. At the time the male pronucleus is formed the paternally derived chromosomes have not completely dispersed and are visualized as a reticulum of condensed and dispersed chromatin. These results indicate that not all the paternally derived chromatin is modified in the same manner during pronuclear development.

ISSN:0148-7280    

DOI:10.1002/mrd.1120050208

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe fine structure, distribution, and fate of cortical granules in human oocytes cultured in vitro are reported.Follicular maturation in women with blocked Fallopian tubes was induced by clomiphene citrate and human chorionic gonadotropin, and preovulatory eggs were obtained by improved methods of laproscopy and oocyte recovery. These oocytes were then inseminated and cultured in a modified Ham's F10 medium for 3 to 72 hr to assess their fertilizability.Cortical granules were observed in all 17 unfertilized oocytes investigated, which had completed various stages of meiotic maturation. A marked increase in their numbers was observed in oocytes cultured for 3 to 6 hr. There was no evidence of spontaneous cortical granule release in any of the oocytes studied.It is concluded that cortical maturation expressed by proliferation of cortical granules is as significant a criterion as nuclear maturation in assessing maturity and fertilizability of oocytes cultured in vitro. A short sojourn in culture before insemination could improve chances of normal fertilization and embryo development, which has been recently achieved in our laboratory.

ISSN:0148-7280    

DOI:10.1002/mrd.1120050209

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

年代:1982

数据来源: WILEY

摘要:

AbstractObservations were made on the sequence of morphologic changes in atresia of medium‐sized preantral follicles in the rat. Ultrastructural studies indicated that in both control and hormonally treated animals granulosa cell changes, including nuclear condensation and alterations in cytoplasmic organelles, occurred prior to effects on the oocyte. In more advanced stages of atresia, extensive disruption of granulosa cell cytoplasm was associated with loss of microvilli and cytoplasmic vacuolization in oocytes. The findings are consistent with the view that follicular atresia begins with alterations in granulosa cells, effects on the oocyte occurring later in the atretic proces

ISSN:0148-7280    

DOI:10.1002/mrd.1120050210

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe ability of isolated porcine oocyte‐cumulus complexes to secrete progesterone and convert androgens to estrogen during two days of culture was examined. We studied the effects of steroids, as well as a partially purified fraction of follicular fluid oocyte maturation inhibitor (Sephadex Peak A OMI), on the ability of oocyte‐cumulus complexes to mature and convert androgen to estrogen.The addition of 0.014, 0.14 or 1.4 μg/ml androstenedione to the culture medium resulted in a substrate dose‐dependent accumulation of estrogen in the culture medium after two days. Oocyte‐cumulus cell complexes secreted more estrogen in the presence of androstenedione than in the presence of testosterone (P<0.05). The addition of 1.4 μg/ml testosterone, androstenedione, or estradiol, but not dihydrotestosterone, inhibited cumulus cell progesterone secretion (P<0.001 versus untreated control culture). Oocyte maturation was not altered by the addition of steroids in doses up to and including 1.4 μg/ml. The Sephadex Peak A OMI fraction of pFFL inhibited oocyte maturation 51% (P<0.01) and progesterone secretion 91% (P<0.01) but had no effect on the conversion of androgens to estrogens. Cumulus cell monolayer formation was inhibited 71.5% (P<0.01) by the Sephadex Peak A OMI fraction and 35.4% (P<0.05) by the Sephadex Peak A OMI fraction plus androstenedione.These studies indicate that porcine oocyte‐cumulus complexes can convert androgens to estrogens and that partially purified OMI does not inhibit conversion of androgens

ISSN:0148-7280    

DOI:10.1002/mrd.1120050211

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

年代:1982

数据来源: WILEY