摘要:

AbstractThe electrophysiological properties of immature and mature oocytes of two crabs were analyzed. Growing immature oocytes of Carcinus maenas and fully grown immature oocytes of Maia squinado had essentially K+dependent resting potentials, Em, of −61 ∓ 1 mV, n=19, and −67.3 ± 0.5 mV, n=68, respectively. Fully grown immature oocytes of Carcinus maenas showed an Em of −40 ± 1.5 mV, n=19, that was k+and Cl−dependent. In mature oocytes of both species, the plasma membrane became exclusively permeable to cl−and the Em attained–41 ± 1 mV, n=49 and −34 ± 1.5 mV, n=27 for Carcinus maenas and Maia squinado, respectively. After in vitro insemination, a dramatic increase in egg membrane permeability to K+was observed. This instantaneously caused a sustained hyperpolarization constituting, for these crabs, the fertilization potential. We observed that concurrently with this electrical response to fertilization, sperm reinitiated the oocyte meiotic maturation previously arrested at the first metaphase. The triggering mechanism of the fertilization potential as well as the possible occurrence of a physiological polys

ISSN:0148-7280    

DOI:10.1002/mrd.1120110102

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe involvement of a kallikrein−kinin system in the motility of mammalian spermatozoa has been suggested by several investigators. We found that incorporation of kallikrein (0.1–1.0) unit/ml) in the sperm incubation medium did not enhance the motility of hamster spermatozoa that were already active. However, this enzyme significantly increased the incidence of the acrosome reaction. Trypsin (1.8–18 units/ml) and chymotrypsin (0.34–3.4 units/ml) also increased the incidence of the acrosome reaction, and accelerated its onset. Kinins (bradykinin and kallidin) added to the medium in a wide concentration range (1 ng/ml to 1 mg/ml) had no marked effects on either the motility or the acrosome reaction. A kallikrein−kinin system is apparently not of primary importance at least for the acrosome reaction. The enhancement of the acrosome reaction by exogenous proteinases may be due in part to accelerated removal or alteration of the sperm surface coat (glycoprotein) by the enzyme peior to the acrosome reaction. Exogenous proteinases may also act synergistically with endogenous (acrosomal) proteinases (and other enzymes) in altering membrane proteins and dispersing the acrosome matrix during the course of teh acrosome

ISSN:0148-7280    

DOI:10.1002/mrd.1120110103

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

年代:1985

数据来源: WILEY

摘要:

AbstractWhen guinea pig spermatozoa are preincubated for 1 hr in Ca2+−free medium containing a low concentration of lysolecithin (LC, 85 μg/ml) and then exposed to 2 mM Ca2+by diluting the preincubation medium with an equal volume of LC−free, 4 mM Ca2+−containing medium, the majority of the spermatozoa undergo acrosome reaction promptly. On the other hand, when the preincubated spermatozoa are exposed to 2 mM Ca2+without reducing the original concentration of LC in the medium, none of them undergo acrosome reaction. These spermatoza can acrosome−react if they are transferred to an LC−free medium. These results and those of some other experiments suggest that in the presistent presence of a high concentration of LC in the medium, exogenous Ca2+essential for the acrosome reaction either does not penetrate the sperm plasma membrane or, if it does, it cannot alter the membrane for the acrosome reaction, at least under the experimental conditions employed. Freeze−fracture examination of the sperm plasma membrane has revealed that small areas or patches free of intramembranous paarticles (IMPs) appear in the membrance during sperm preincubation, and these IMP−free areas expand drastically in response to Ca2+when the LC conccentration in the medium is reduced at the time Ca2+is added to the medium. In contrast, IMP−free areas remain unchanged even after exposure of spermatozoa to Ca2+if the concentration of LC remains at its original l

ISSN:0148-7280    

DOI:10.1002/mrd.1120110104

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

年代:1985

数据来源: WILEY

摘要:

AbstractArachidonic acid can be oxidized via the cyclooxygenase pathway to produce prostaglandins and via the 5−lipoxygenase pathway to produce leukotrienes. These substances are known to be extremely potent regulators of cellular function in somatic tissues, particularly during inflammatory reactions. Recent studies have implicated cyclooxygenase−derived products in preventing polyspermy in sea urchins [Schuel et al, Gamete Res 10:9–19, 1984]. FPL−55712, a receptor antagonist for leukotrienes in somatic tissues, causes a dose−(1–10 μM) and sperm−density−dependent induction of polyspermic fertilization in sea urchins if added before the egg completes the cortical reaction (elevation of the fertilization envelope). Eggs pretreated with FPL−55712 become polyspermic upon subsequent insemination with untreated sperm in sea water. Sperm pretreated with the drug do not cause polyspermy when used to inseminate untreated eggs. The 5−lipoxygenase inhibitor BW775C also promotes polyspermy. FPL−55712 and BW755C do not retard elevation of the fertilization envelope. These findings imply that (1) leukotrienes may be produced via the 5−lipoxygenase pathway during fertilization in sea urchins, and (2) the reaction of leukotrienes with putative receptors on the egg's surface may modulate its receptivity to sperm during the cortical reaction, and thereby

ISSN:0148-7280    

DOI:10.1002/mrd.1120110105

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

年代:1985

数据来源: WILEY

摘要:

AbstractIn this report we describe a new method of immobilizing intact mouse preimplantation embryos and their dissociated blastomeres on a flat substrate so that they may be processed en masse for electron microscopy. The embryos can be arranged so that they will be coplanar and grouped together closely enough to be included within the same plane of section. The substrate consists of Thermonex plastic coverslips that have been coated with a layer of fibroblasts or with fibronectin. The plant lectin phytohemaggiutinin (PHA) is used as a ligand to adhere the embryos onto the coverslips. This method is compatible with other ligands and with a variety of immunocytochemical procedures and can be used with live or fixed embryos.

ISSN:0148-7280    

DOI:10.1002/mrd.1120110106

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of in vitro aging of cumulus−intact versus cumulus−free metaphase II mouse oocytes were studied with respect to zona solubility and fertilization rates. Furthermore, zygotes from the in vitro fertilization studies were incubated and their developmental progress was recorded. The zona pellucida showed a gradual increase in resistance to dissolution by α−chymotrypsin with in vitro aging over a period of 6 hr. This effect was greater in cumulus−free as compared to cumulus−intact ova, but it was not nearly as profound as that seen in the control in vivo fertilized eggs. The fertilization rate of in vitro aging cumulus−intact ova compared favorably with the control in vivo aging group over a 6−hr time period. This was in sharp contrast to the decreased fertilization rate of in vitro aging cumulus−free ova over the same period of time. Lastly, development of zygotes to the blastocyst stage was also evaluated. The rate of first cleavage was similar in all experimental groups and compared favorably with the in vivo controls. However, further development to blastocysts of in vitro aged cumulus−free ova showed a marked decrease when compared to the cumulus−intact group and the in vivo fertilized controls. Thus we established a direct relationship between zona digestion time of in vitro aged cumulus−free oocytes and a decrease of fertilizat

ISSN:0148-7280    

DOI:10.1002/mrd.1120110107

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

年代:1985

数据来源: WILEY

摘要:

AbstractA proteolytic enzyme capable of cleaving intact proteins and synthetic substrates α−N−benzoyl−DL−arginine β−naphthylamide (Bz‐Arg‐NNap), α‐N‐benzoyl‐L‐arginine p‐nitroanilde (Bz‐Arg‐NPhNO2), and α‐N‐benzoyl‐L‐arginine ethyl ester (Bz‐Arg‐OEt) was purified 92– fold from the rabbit testes. The enzyme exhibited optimal activity at pH 9.0 and 50°C. The polyacrylamide gel electrophoresis and sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis of the purified enzyme demonstrated multiple forms; the major band in the SDS‐polyacrylamide gel electrophoresis corresponded to a Mt48,000. The same value was established by the gel filtration over Sephadex G‐75. The rabbit testicular alkaline proteinase (TAP) resembled acrosin in the hydrolysis of Bz‐Arg‐OEt. However, CaCl2, a potential stimulator of acrosin activity, inhibited the alkaline proteinase. The strong inhibitors of acrosin, eg pheny methyl sulphonyl fluoride (PMSF), tosyl lysine chloromethyl ketone (TLCK), and benzamidine did not inhibit the alkaline proteinase. TAP was activated by an acrosin inhibitor isolated from the rabbit testes. Since 0.5 M KCl was necessary for complete extraction of the enzyme and the bulk of the activity was present in 9,000g pellet of the testicular homogenate. The alkaline proteinase

ISSN:0148-7280    

DOI:10.1002/mrd.1120110108

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of the putative maturation inhibitor in porcine follicular fluid on gonadotropinstimulated reversal of cyclic adenosine monophosphate (cAMP)‐maintained meiotic arrest in mouse oocytes in vitro were assessed in this study. When cumulus cell‐enclosed oocytes were cultured in a suboptimal inhibitory concentration of dibutyryl cAMP (dbcAMP), the effect of follicle‐stimulating hormone (FSH) on oocyte maturation was initially inhibitory at 3 hr, but stimulatory at 6 hr. Supplementation of the medium with an ultrafiltrate of porcine follicuiar fluid (PM10‐filtrate) completely suppressed FSH‐promoted reversal of inhibition at 6 hr. Charcoal extraction eliminated this effect of the PM10‐filtrate. FSH reversed the inhibition of maturation of cumulus cell‐enclosed oocytes maintained by a high concentration of dbcAMP and suboptimal concentrations of the phosphodiesterase inhibitor, 3‐isobutyl‐1‐methyl xanthine (IBMX), during a 21–22‐hr culture period. However, the effect of a completely inhibitory concentration of IBMX was not reversed by gonadotropin. A component of serum was also found to inhibit FSH reversal of dbcAMP‐maintained meiotic arrest, and this activity was removed by charcoal extraction. In addition, when oocytes were cultured in medium containing a suboptimal concentration of dbcAMP plus a low molecular weight fraction (<1,000) of porcine follicular fluid, porcine serum, or fetal bovine serum, a synergistic inhibition of maturation was observed. Experiments with highly purified gonadotropins revealed that reversal of dbcAMP‐maintained meiotic arrest occurred only in response to FSH; neither highly purified luteinizing hormone nor human chorionic gonadotropin could mimic this action of FSH. Also, this effect was mediated by the cumulus cells, since FSH could not reverse dbcAMP‐maintained meiotic arrest in denuded oocytes. Furthermore, elevating cAMP levels in denuded oocytes augmented, rather than reversed, the inhibitory action of dbcAMP on oocyte maturation. These data therefore suggest that dbcAMP‐ or IBMX‐maintained meiotic arrest in vitro is reversed by an FSH‐stimulated, cAMP‐dependent process mediated by the cumulus cells and demonstrate that a factor present both in follicular fluid and serum pre

ISSN:0148-7280    

DOI:10.1002/mrd.1120110109

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to analyze the effect of postovulatory ‘aging’ in the oviduct on the rate of zygotic development. Two ovulatory ages were tested: oocytes collected from the oviducal ampullae 1) soon after ovulation (denoted freshly ovulated) or 2) 7‐hour postovulation. All the oocytes were from superovulated immature rats. By manipulation of the timing of the ovulatory hormone treatment, it was possible to place both types of oocytes into sperm suspension from the same pool and at the same time. The oocytes and spermatozoa were coincubated overnight. Cleavage was established by interference contrast microscopy. The time of the first cleavage of ova from the 7‐hour postovulation group was clearly advanced. Because the cleavage time curves were not parallel, no reliable estimate of the time difference could be made, but it was clearly in the range of 2 hr. This shift could not be related to any difference in the time of sperm penetration. Both groups of oocytes underwent penetration by spermatozoa at the same time. The time interval between maximal sperm penetration (94% of oocytes in both groups) and maximal cleavage (50% in both groups) was 23 hr in the freshly ovulated and 21 hr in the 7‐hour postovulatory eggs. Nor was the difference related to polyspermy, which was approximately 14% in both groups. These results support the hypothesis that developmental processes are under way in the oocyte before fertilization, but at a much slower rate than after fert

ISSN:0148-7280    

DOI:10.1002/mrd.1120110110

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.1120110101

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

年代:1985

数据来源: WILEY