TY - JOUR
T1 - Penetration of porcine oocytes during maturation in vitro by cryopreserved, ejaculated spermatozoa
AU - Wang, W. H.
AU - Abeydeera, L. R.
AU - Okuda, K.
AU - Niwa, K.
PY - 1994
Y1 - 1994
N2 - The present study was conducted to examine the penetrability in vitro of immature porcine oocytes with or without cumulus cells. Porcine oocytes were cultured for 0-36 h, at 39°C in 5% CO2 in air, in modified tissue culture medium 199 (TCM-199B at pH 7.4) supplemented with 10 IU cCG/ml, 10 IU hCG/ml, and 1 μg estradiol-17β/ml. At various times after the beginning of culture, some oocytes were freed from the cumulus (cumulus and corona cells), and cumulus-intact or cumulus-free oocytes were inseminated with cryopreserved ejaculated spermatozoa in TCM-199B (pH 7.8) containing 5 mM caffeine. When cumulus-free oocytes were examined 14 h after insemination, high proportions (69-84%) were penetrated and there were no significant differences among different periods of maturation culture. The incidence (47-68%) of polyspermy and the number (1.7-3.1) of spermatozoa that penetrated per oocyte were also not significantly different among oocytes cultured for 0-36 h. In cumulus- intact oocytes, however, the first evidence of penetration (15%) was observed in oocytes cultured for 6 h. The penetration rates increased significantly as the period of culture was prolonged up to 24 h. Almost all (95-100%) oocytes were penetrated when they were inseminated 24-36 h after the beginning of culture, by which time the cumulus masses showed moderate to complete expansion except for the corona radiata. A similar correlation was also observed for incidence of polyspermy and number of spermatozoa penetrated per oocyte. The presence of well-expanded cumulus around the oocyte during fertilization promoted male pronuclear formation in penetrated oocytes. The results of the present study provide evidence that immature porcine oocytes are equally penetrable in vitro at any stage of maturation when they have been freed from the cumulus.
AB - The present study was conducted to examine the penetrability in vitro of immature porcine oocytes with or without cumulus cells. Porcine oocytes were cultured for 0-36 h, at 39°C in 5% CO2 in air, in modified tissue culture medium 199 (TCM-199B at pH 7.4) supplemented with 10 IU cCG/ml, 10 IU hCG/ml, and 1 μg estradiol-17β/ml. At various times after the beginning of culture, some oocytes were freed from the cumulus (cumulus and corona cells), and cumulus-intact or cumulus-free oocytes were inseminated with cryopreserved ejaculated spermatozoa in TCM-199B (pH 7.8) containing 5 mM caffeine. When cumulus-free oocytes were examined 14 h after insemination, high proportions (69-84%) were penetrated and there were no significant differences among different periods of maturation culture. The incidence (47-68%) of polyspermy and the number (1.7-3.1) of spermatozoa that penetrated per oocyte were also not significantly different among oocytes cultured for 0-36 h. In cumulus- intact oocytes, however, the first evidence of penetration (15%) was observed in oocytes cultured for 6 h. The penetration rates increased significantly as the period of culture was prolonged up to 24 h. Almost all (95-100%) oocytes were penetrated when they were inseminated 24-36 h after the beginning of culture, by which time the cumulus masses showed moderate to complete expansion except for the corona radiata. A similar correlation was also observed for incidence of polyspermy and number of spermatozoa penetrated per oocyte. The presence of well-expanded cumulus around the oocyte during fertilization promoted male pronuclear formation in penetrated oocytes. The results of the present study provide evidence that immature porcine oocytes are equally penetrable in vitro at any stage of maturation when they have been freed from the cumulus.
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U2 - 10.1095/biolreprod50.3.510
DO - 10.1095/biolreprod50.3.510
M3 - Article
C2 - 8167222
AN - SCOPUS:0028078749
VL - 50
SP - 510
EP - 515
JO - Biology of Reproduction
JF - Biology of Reproduction
SN - 0006-3363
IS - 3
ER -