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1.
Mouse preovulatory oocytes, zygotes, parthenogenetically activated pronuclear oocytes, and early embryos, as well as hamster zygotes, were analyzed, by autoradiography, for the distribution of either “maternal” or newly synthesized RNAs. Early mouse embryos were also examined for the distribution of newly replicated DNA. Special attention was attributed to NLBs in oocytes or to NPBs in early embryos. In mouse oocytes, [5-3H]uridine radioactivity accumulated (after a 2-hr pulse) in vitro, in addition to other nuclear compartments, in the central compact material of the NLBs. There was no cytoplasmic labeling. In all parthenogenetic pronuclear embryos developed from similarly labeled oocytes, this label was distinctly detectable in the central compact material of the NPBs; less intensive labeling was seen in the nucleoplasm and cytoplasm. On the contrary, the central compact part of the mouse NPB did not show labeling in DNA after a continuous culture with [6-3H]thymidine. In mouse and hamster pronuclear zygotes, convincing evidence was obtained for a lack of any newly synthesized nucleic acids in the compact material of NPBs using 4- to 10-hr culture with [8-3H]adenosine. Based on these data, it was shown that the NLBs of oocytes or NPBs of early embryos probably contain RNAs synthesized during the last stages of antral follicle oocyte differentiation. This unique pathway of RNAs in the oocyte—embryo system may explain the specific morphology of both oocyte and early embryo “nucleoli.” © 1995 Wiley-Liss, Inc. 相似文献
2.
J. M. Cummins W. R. Edirisinghe Y. Odawara R. G. Wales J. L. Yovich 《Molecular reproduction and development》1989,24(4):461-469
Cumulus-free mouse oocytes were subjected to zona opening by cracking with microhooks (ZC) or acid drilling (ZD) and fixed 30–90 min after insemination (105 pre-capacitated motile sperms/ml). Ultrastructural observations were made on serially thin-sectioned oocytes: 15 ZC and 12 ZD. The zona lesion in ZC oocytes was a clean cut, whereas in ZD oocytes it formed a patchy area of partial zona loss, with reduced microvillar height on the underlying oocyte surface. Spermatozoa were observed within the perivitelline space and partially fusing with the oocyte after 30 min in both situations. Only acrosome-reacted sperm heads were observed to fuse: acrosome intact forms were generally in contact with the zona pellucida, either with the inner or outer surface. Acrosome-intact spermatozoa were also observed deeply embedded in the zona matrix, possibly indicating surface enzyme activity preceding the membrane fusion events of the acrosome reaction proper. The observations are consistent with the need for spermatozoa to make contact preferentially with the zona pellucida during the course of the acrosome reaction. 相似文献
3.
Here we show that hydroxyl radical (•OH) generated through the Fenton reaction alters metaphase-II mouse oocyte microtubules (MT) and chromosomal alignment (CH). Metaphase-II mouse oocytes, obtained commercially, were grouped as follows: control, hydrogen peroxide (H2O2), Fe(II), and combined (Fe(II) +H2O2) treatments. After 7–10 min of incubation at 37 °C, MT and CH were evaluated on fixed and stained oocytes and scored by two blinded observers. Pearson χ2 test and Fisher exact test were used to compare outcomes between controls and treated groups and also among the treated groups. Our results showed that poor scores for MT and CH increased significantly in oocytes treated with a combination of H2O2 and Fe(II) (p<0.001); oocytes treated with H2O2 alone or Fe(II) alone showed no or few changes compared to control. Comparison of oocyte groups that received increasing concentrations of H2O2 and a fixed amount of Fe(II) showed that 70–80% demonstrated poor scores in both MT and CH when pretreated with 5 μM H2O2, and this increased up to 90–100% when treated with 10–20 μM H2O2. Hydroxyl radical generated by H2O2-driven Fenton reaction deteriorates the metaphase-II mouse oocyte spindle and CH alignment, which is thought to be a potential cause of poor oocyte quality. Thus, free iron and/or ROS scavengers could attenuate the •OH-mediated spindle and chromosomal damage, thereby serving as a possible approach for further examination as a therapeutic option in inflammatory states. 相似文献
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Incubation of recently ovulated mouse oocytes in various concentrations of local anesthetics and phenothiazine tranquilizers initiates the completion of meiosis and the formation of pronuclei. The potency with which these drugs induce oocyte activation is comparable to their relative ability to displace Ca2+ from artificial lipid membranes. Oocyte activation induced by these drugs is inhibited by Ca2+. Perturbation of the plasma membrane of the oocyte by these drugs may displace Ca2+, which is responsible for the integrity of the microtubule-microfilament system that normally maintains the ovulated mammalian oocyte blocked at the Metaphase II of meiosis until sperm penetration. 相似文献
6.
J.L. Hill K. Hammar P.J.S. Smith D.J. Gross 《Molecular reproduction and development》1999,53(2):244-253
Epidermal growth factor (EGF) has received much attention recently for its positive effects on mammalian oocyte maturation and embryo development and its potential importance in cytoplasmic maturation of oocytes. Calcium (Ca2+) homeostasis in germinal vesicle stage oocytes has also been suggested to play a role in cytoplasmic maturation. This study examined the effects of EGF on Ca2+ mobilization as measured by its efflux from mouse oocytes at three time periods throughout maturation (0–4 hr, 4–8 hr, and 12 hr). Immature cumulus oocyte complexes (COCs) removed from the ovary for less than 4 hr exhibit oscillations in Ca2+ efflux that initiated 5–30 min following EGF stimulation. This response was not observed in COCs matured for 4–8 hr or 12 hr or in unstimulated 0–4 hr COCs. Denuded oocytes and cumulus cells did not show the same response to EGF (8.2 nM and 16.4 nM). Immunohistochemistry for detection of the EGF receptor along with EGF internalization studies showed that receptors are present both on cumulus cells and the oocyte but EGF appears to be internalized mainly by the cumulus cells. These data demonstrate that EGF induces oscillations in Ca2+ efflux in COCs 0–4 hr old and this response is mediated by the cumulus cells. Mol. Reprod. Dev. 53:244–253, 1999. © 1999 Wiley‐Liss, Inc. 相似文献
7.
Although it is established that cAMP accumulation plays a pivotal role in preventing meiotic resumption in mammalian oocytes, the mechanisms controlling cAMP levels in the female gamete have remained elusive. Both production of cAMP via GPCRs/Gs/adenylyl cyclases endogenous to the oocyte as well as diffusion from the somatic compartment through gap junctions have been implicated in maintaining cAMP at levels that preclude maturation. Here we have used a genetic approach to investigate the different biochemical pathways contributing to cAMP accumulation and maturation in mouse oocytes. Because cAMP hydrolysis is greatly decreased and cAMP accumulates above a threshold, oocytes deficient in PDE3A do not resume meiosis in vitro or in vivo, resulting in complete female infertility. In vitro, inactivation of Gs or downregulation of the GPCR GPR3 causes meiotic resumption in the Pde3a null oocytes. Crossing of Pde3a−/− mice with Gpr3−/− mice causes partial recovery of female fertility. Unlike the complete meiotic block of the Pde3a null mice, oocyte maturation is restored in the double knockout, although it occurs prematurely as described for the Gpr3−/− mouse. The increase in cAMP that follows PDE3A ablation is not detected in double mutant oocytes, confirming that GPR3 functions upstream of PDE3A in the regulation of oocyte cAMP. Metabolic coupling between oocytes and granulosa cells was not affected in follicles from the single or double mutant mice, suggesting that diffusion of cAMP is not prevented. Finally, simultaneous ablation of GPR12, an additional receptor expressed in the oocyte, does not modify the Gpr3−/− phenotype. Taken together, these findings demonstrate that Gpr3 is epistatic to Pde3a and that fertility as well as meiotic arrest in the PDE3A-deficient oocyte is dependent on the activity of GPR3. These findings also suggest that cAMP diffusion through gap junctions or the activity of additional receptors is not sufficient by itself to maintain the meiotic arrest in the mouse oocyte. 相似文献
8.
Isolated fully grown mouse oocytes, arrested in dictyate of the first meiotic prophase, synthesize a protein with an apparent molecular weight of 28,000 which is localized in the germinal vesicle of the oocyte (germinal vesicle-associated protein; GVAP). Analyses of the distribution of GVAP have been carried out on SDS-polyacrylamide gels using oocytes cultured in vitro in the presence of [35S]methionine or [3H]lysine and germinal vesicles isolated individually from these cultured oocytes. The results of such analyses show that GVAP contains only about 2% of the total radiolabel incorporated into mouse oocyte proteins, but as much as 40% of the total radiolabel incorporated into proteins associated with isolated germinal vesicles. These measurements indicate that GVAP is at least 1000-fold more concentrated in the germinal vesicle than in the cytoplasm of the oocyte. Furthermore, the synthesis and phosphorylation of GVAP are apparently terminated at a time which coincides with germinal vesicle breakdown during spontaneous meiotic maturation of mouse oocytes in vitro. Although the exact nature of GVAP is not known as yet, it appears to be an example of a protein that is selectively sequestered in the germinal vesicle of the oocyte during oogenesis and whose synthesis and modification are dependent upon the presence of an intact germinal vesicle. 相似文献
9.
The activity of the enzyme glucose-phosphate isomerase (GPI-1) in mouse oocytes is subject to regulation by the cis-acting gene Gpi-lta. Electrophoretic analysis of oocytes from 9- and 10-day-old mice showed that oocyte-specific regulation of GPI-1 is not observed in germ cells that have not started to grow (20 μm diameter) but appears as soon as oocyte growth begins (30 μm or larger). Three in vitro culture systems were used to examine the relation of GPI-1 expression to oocyte growth: culture of intact neonatal ovaries, and co-culture of dissociated oocytes and somatic cells from neonatal and from 13-day foetal ovaries. In all three systems modification of GPI-1 expression always occurred when oocyte growth began, showing that the presence of a normal follicle is not necessary for the expression of the gene Gpi-lta. 相似文献
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Incorporation of tritiated adenosine into mouse ovum RNA 总被引:1,自引:0,他引:1
R Bachvarova 《Developmental biology》1974,40(1):52-58
The total RNA of ovulated mouse ova has been examined by polyacrylamide gel electrophoresis. The amount of RNA present in the two main peaks observed, 28 S and 18 S ribosomal RNA, has been estimated as 0.20 ng.The RNA of ovulated mouse ova was labeled by exposure of growing mouse oocytes to adenosine-8-3H in vivo. For this purpose a small volume of a concentrated solution of the precursor was injected into the ovarian bursa, and ova were collected by superovulation at various subsequent times. The major growth phase of the oocyte is known to lie between 20 and 6 days before ovulation. Significant incorporation into egg RNA was observed when bursal injection was performed between 19 and 7 days, but not between 5 days and 1 day before ovulation.The types of labeled RNA in ova ovulated at five intervals between 19 and 7 days after bursal injection of adenosine-8-3H or uridine-5,6-3H were analyzed by polyacrylamide gel electrophoresis. The distribution of label on the gels demonstrated that the bulk of the label appeared in ribosomal RNA and transfer RNA. In addition labeled heterogeneous RNA was estimated to represent 10–15% of the total incorporation. 相似文献
12.
Hyejin Shin Dayoung Park Jiyeon Kim MinYeong Nam Sojung Kwon DaEun Um JiEun Oh Esther Youn YhongHee Shim KayUwe Wagner Jin Hyun Jun HyeRyun Kim Haengseok Song Hyunjung Jade Lim 《Cell proliferation》2022,55(10)
ObjectiveAs a component of Endosomal Sorting Complex Required for Transport (ESCRT) complex I, the tumor susceptibility gene 101 (Tsg101) carries out multiple functions. In this work, we report that oocyte‐specific deletion of tumor susceptibility gene 101 (Tsg101) leads to age‐dependent oocyte demise in mice.Materials and Method Tsg101 floxed mice (Tsg101 f/f ) were bred with Zp3 cre transgenic mice to examine oocyte‐specific roles of Tsg101. Multiple cellular and molecular biological approaches were taken to examine what leads to oocyte demise in the absence of Tsg101.ResultsThe death of oocytes from Zp3 cre /Tsg101 f/f (Tsg101 d/d thereafter) mice showed a strong correlation with sexual maturation, as gonadotropin‐releasing hormone antagonist injections improved the survival rate of oocytes from 5‐week‐old Tsg101 d/d mice. Maturation of oocytes from prepubertal Tsg101 d/d mice proceeded normally, but was largely abnormal in oocytes from peripubertal Tsg101 d/d mice, showing shrinkage or rupture. Endolysosomal structures in oocytes from peripubertal Tsg101 d/d mice showed abnormalities, with aberrant patterns of early and late endosomal markers and a high accumulation of lysosomes. Dying oocytes showed plasma membrane blebs and leakage. Blockage of endocytosis in oocytes at 4°C prevented cytoplasmic shrinkage of oocytes from Tsg101 d/d mice until 9 h. The depletion of tsg‐101 in Caenorhabditis elegans increased the permeability of oocytes and embryos, suggesting a conserved role of Tsg101 in maintaining membrane integrity.ConclusionsCollectively, Tsg101 plays a dual role in maintaining the integrity of membranous structures, which is influenced by age in mouse oocytes. Tsg101 deficiency in mouse oocytes leads to a complex phenotype involving the plasma membrane (PM). These oocytes are normal until mice reach five weeks of age when oocytes begin to show PM rupture, PM blebbing, and cytoplasmic shrinkage. PM blebbing and cytoplasmic shrinkage can be postponed with a general endocytosis block, but death ensues. In both mouse and in Caenorhabditis elegans, Tsg101 plays a crucial role in maintaining the integrity of PM. 相似文献
13.
A panel of anti-oocyte antibodies was raised against unfertilized zona-free mouse oocytes by intrasplenic immunization and checked for their effects on in vitro fertilization. Four antibodies decreased the fertilization rate from about 90% in controls to 8% (B5-2 F7), 12% (A2-2 A7), 13% (4-G1), and 25% (A2-2 F2), when the sperm cell concentration was 1 × 105 to 1 × 106. Antigen localization: All the antibodies labelled components in the cell membrane of zona-free oocytes as demonstrated by indirect immunofluorescence and/or by complement-mediated oocyte lysis. In various patterns, the ooplasm and zona pellucida were also labelled with different intensities. Western blotting: A2-2 A7 and A2-2 F2 recognized a protein with a molecular weight of approximately 65 kDa, while antibody B5-2 F7 bound a 97 kDa protein. Complement activation and complement-mediated oocyte lysis: Systemically injected antibodies, C3 and C4 were detected on zona-free oocytes recovered from the mouse oviduct indicating the activation of C3 and C4 by antigen-antibody complexes. The recovered oocytes were not damaged, suggesting a presence of complement-regulating factors. In vitro, however, a large number of zona-free oocytes preincubated with antibodies were lysed or protruded ooplasma vesicles in complement-active serum. Stage, tissue, and species specificity: None of the antibodies, except A2-2 A7, showed a positive immunolabelling to the pronuclear stage. Antibodies 4-G1 and A2-2 F2 cross-reacted with the ovarian oocytes. No antibodies bound to any of the tissues tested, indicating that the corresponding antigen epitopes are not commonly expressed. A2-2 A7, A2-2 F2, and B5-2 F7 cross-reacted with hamster and human unfertilized oocytes, suggesting the presence of developmentally conserved molecules and the possibility to apply these antibodies in hamster and human in vitro fertilization. It is concluded that the approach used could be a useful strategy in searching for anti-fertilization antibodies for human contraception. © 1996 Wiley-Liss, Inc. 相似文献
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Summary Externally applied membrane permeable cAMP derivatives and the injection of cAMP induce oocyte maturation in several species
of hydrozoans. This technique for inducing oocyte maturation has been used to study ion permeability changes, maturation promoting
factor activity and surface tension changes during maturation. Oocyte membrane potential remains constant during maturation.
Cyclic AMP induced maturation proceeds in the absence of external Ca2+, K−, Mg2+ or Na+. Cytoplasm from maturing oocytes that induces oocyte maturation when it is injected into untreated oocytes is produced during
cAMP induced maturation. Surface tension, as measured by the application of a standardized force that mechanically deforms
individual oocytes, declines during the first part of maturation. This is followed by a sharp rise and fall of surface tension
at first and second polar body formation that accompanies a slow rise in the resistance of oocytes to deformation during the
last part of maturation. The production of maturation promoting factor activity and some of the changes in surface tension
during maturation can occur in the absence of germinal vesicle material. Two early developmental events that follow oocyte
maturation are the production of sperm chemoattractant and calcium channel function. Neither of these events occurs in eggs
that have undergone maturation in the absence of germinal vesicle material. The addition of germinal vesicle contents from
oocytes to eggs that have undergone maturation in the absence of germinal vesicle material initiates calcium channel function.
This experiment indicates that the germinal vesicle contains factors that are necessary for post-maturation developmental
events. 相似文献
16.
Hideki Igarashi Eiji Takahashi Masahiko Hiroi Katsuhiko Doi 《Molecular reproduction and development》1997,48(3):383-390
Aging of oocytes, being not fertilized after ovulation for a prolonged time, considerably affects normal development of the fertilized oocyte. We examined effects of the aging on a series of highly repetitive Ca2+ transients commonly seen in fertilized mouse oocytes (Ca2+ oscillations). Frequency of Ca2+ oscillations in the aged oocyte [20 hrs after induction of superovulation by i.p. human chorionic gonadotropin (hCG)] was significantly higher (34.1 ± 5.8 1/hr) than the fresh oocyte (14 hr post-hCG, 21.8 ± 7.9 1/hr). Rates of rise and fall of individual Ca2+ transient in the aged oocyte were significantly slower than the fresh oocyte, whereas durations of individual Ca2+ transients were similar. When extracellular Ca2+ was raised from 2.04 mM to 5.00 mM, aged oocytes showed significant prolongation of the duration of individual Ca2+ transient, that resulted in a sustained elevation of intracellular Ca2+ ([Ca2+]i) in 33% of the aged oocyte. Transient increase in [Ca2+]i by photolysis of a caged Ca2+, Nitr-5, injected into cytoplasm was completely restored in the fresh oocyte [fluorescence intensity of [Ca2+]i indicator dye Fluo-3 (F480) returned to 97 ± 2% of the control level, time constant = 37 ± 9 sec]. In contrast, in the aged oocyte, restoration of F480 following Nitr-5 photolysis was incomplete (115 ± 12% of the control) and slow (time constant = 64 ± 23 sec). Because inhibition of the Ca2+ pump of the endoplasmic reticulum (ER) by 5 μM thapsigargin almost completely inhibited restoration of F480 following Nitr-5 photolysis in the fresh oocyte, we conclude that the aging-related changes in Ca2+ oscillations may be accounted for by dysfunction of intracellular Ca2+ regulation, presumably of the Ca2+ pump of the ER. Mol. Reprod. Dev. 48:383–390, 1997. © 1997 Wiley-Liss, Inc. 相似文献
17.
Oocytes at several stages of growth have been isolated by enzymatic digestion and/or physical disruption of ovaries excised from juvenile and adult mice. The absolute rates of total protein synthesis and tubulin synthesis in these isolated oocytes were determined by measuring sizes of the endogenous methionine pool and apparent rates of incorporation of [35S]methionine into total protein and tubulin using methods described previously (R. M. Schultz, M. J. LaMarca, and P. M. Wassarman, 1978,Proc. Nat. Acad. Sci. USA,75, 4160;R. M. Schultz, G. E. Letourneau, and P. M. Wassarman, 1979,Develop. Biol.,68, 341). The size of the endogenous methionine pool increases approximately 350-fold during oocyte growth, from 0.16 fmole in nongrowing oocytes (12 μm) to 56 fmole in fully grown oocytes (85 μm). Since the volume of mouse oocytes also increases about 350-fold during growth, the concentration of intracellular free methionine remains constant at approximately 170 μM. The absolute rate of protein synthesis increases from 1.1 to 41.8 pg/hr/oocyte for nongrowing and fully grown mouse oocytes, respectively. Since this represents about a 38-fold increase in the absolute rate of protein synthesis, the rate of synthesis per picoliter of cytoplasm actually decreases nearly 10-fold during oocyte growth. These measurements indicate that the growing mouse oocyte itself is capable of synthesizing only about 50% of the protein found in fully grown oocytes. Tubulin is one of the major proteins synthesized by growing mouse oocytes since the absolute rate of tubulin synthesis is, on the average, 1.8% of total protein synthesis. The absolute rate of tubulin synthesis increases from 0.4 to 0.6 pg/hr/oocyte as the oocyte grows from 40 to 85 μm in diameter. However, overall, the percentage of total protein synthesis devoted to the synthesis of tubulin actually declines somewhat during this phase of growth, from 2 to 1.5%. Although equimolar amounts of tubulin subunits are present in microtubules, the ratio of absolute rate of synthesis of the β subunit to that of the α subunit varies from 1.3 to 2.0 throughout oocyte growth. High-resolution two-dimensional gel electrophoretic analyses of [35S]methionine-labeled proteins reveal that many changes take place in the pattern of protein synthesis during oocyte growth. 相似文献
18.
Sandra Cecconi Gianna Rossi Massimo De Felici Rosella Colonna 《Molecular reproduction and development》1996,44(4):540-546
We have evaluated the possibility that mouse oocyte growth in vitro could be achieved under the influence of soluble compound(s) released by different somatic cell types. For this purpose, zona-free denuded oocytes from 12-day-old mice were cultured on monolayers of NIH-3T3 fibroblasts, which are able to establish gap junctional communications with them, in the presence or absence of media conditioned by preantral granulosa cells or by Sertoli cells, plated at increasing concentrations from 0.3–1 × 106 ml−1 cells. After 3 days, no increase in vitellus diameter was recorded from fibroblast-coupled oocytes maintained in culture medium or in the presence of media conditioned by 0.3 × 106 ml−1 Sertoli cells. By contrast, increasing proportions of coupled oocytes grew, provided the continuous presence of media conditioned by 0.5 or 1 × 106 ml−1 Sertoli cells, or by 0.3, 0.5, and 1 × 106 ml−1 preantral granulosa cells. Since the ligand of c-kit, the growth factor KL, promotes the growth in vitro of oocytes cultured in follicles from 8-day-old mice, an antibody against mouse KL was used to evaluate whether in our culture conditions KL might also be responsible for the growth of oocytes from 12-day-old mice. No inhibition of growth was evident in oocytes cultured directly on preantral granulosa or Sertoli-cell monolayers. Furthermore, the growth of fibroblast-coupled oocytes cultured in media conditioned by preantral granulosa cells was not significantly affected by the presence of this antibody during culture. By contrast, a high percentage of oocytes cultured on fibroblasts in the presence of media conditioned by Sertoli cells showed a significant inhibition of growth and no metabolic cooperativity. It was concluded that, besides KL, other bioactive factor(s) released by either preantral granulosa or Sertoli cells can induce a significant stimulation of mouse oocyte growth in vitro. © 1996 Wiley-Liss, Inc. 相似文献
19.
Serine has roles in cell metabolism besides protein synthesis including providing one-carbon units to the folate cycle. Since growing mouse oocytes undergo a burst of folate accumulation as they near full size, we have investigated whether oocytes transport serine. Substantial serine transport appeared in oocytes near the end of their growth. Serine transport continued when oocytes resumed meiosis but ceased partway through first meiotic metaphase, remaining quiescent in mature eggs in second meiotic metaphase. The serine transporter was sodium dependent and inhibited by alanine, cysteine, leucine, or histidine, and had a Michaelis–Menten constant (Km) for serine of 200 µM. Unexpectedly, exposing cumulus cell-enclosed oocytes to the physiological mediator of meiotic arrest, natriuretic peptide precursor Type C, substantially stimulated serine transport by the enclosed oocyte. Finally, in addition to transport by the oocyte itself, cumulus cells also supply serine to the enclosed oocyte via gap junctions within intact cumulus–oocyte complexes. 相似文献
20.
The uptake and efflux of 22Na and 42K were studied in denuded Rana pipiens oocytes following progesterone induction of the resumption of meiotic maturation. Coincident with the breakdown of the large nucleus, or germinal vesicle, there is a virtual disappearance of K+ permeability of the oocyte plasma membrane. Only about 1–2% of the total [K+]i is exchanged by completion of nuclear breakdown (8–10 hr) and accounts for the finding that there is no detectable change in total [K+]i during the first meiotic division (20–24 hr). In the case of Na+, influx, exchange, and efflux kinetics were unchanged during the first meiotic division, with 20 and 35% of the total oocyte Na+ exchanging by the completion of nuclear breakdown and first meiotic division, respectively. Removal of Na+ from the incubation medium produced and earlier nuclear breakdown, whereas a K-free medium delayed breakdown. There was no effect of 10 μm/ml tetrodotoxin or 10?5M strophanthidin on the time course of nuclear breakdown. Thus one action of progesterone appears to be a selective turning off of “K channels” in the oocyte plasma membrane. The disappearance of K selectivity of the oocyte plasma membrane coincides with plasma membrane depolarization, as well as nuclear swelling and breakdown. 相似文献