Influence of ovarian hyperstimulation and ovulation induction on the cytoskeletal dynamics and developmental competence of oocytes.
This study was undertaken to determine the effects of gonadotrophin on cytoskeletal dynamics and embryo development and its role in improving the retrieval of developmentally competent oocytes. Female golden hamsters were injected with human chorionic gonadotrophin (hCG; 5-, 7.5- or 15-IU) on the day 4 of estrus, pregnant mare serum gonadotrophin (PMSG; 5-, 7.5- or 15-IU) on the day 1 of estrus, or 15-IU hCG at 56 hr post-15-IU PMSG injection in any cycle except estrus. Increasing the hCG dose decreased not only retrieval rate of 2-cell embryo but development to blastocyst after subsequent in vitro culture. Whereas, although increasing the PMSG dose induced increasing the number of 2-cell embryo and blastocyst, 15-IU PMSG injection caused retardation of development to blastocyst. No 2-cell embryos were retrieved by injecting both PMSG and hCG. The injections of 15-IU hCG and 7.5- or 15-IU PMSG inhibited the proliferation of trophectodermal and inner cell mass cells, respectively. Gonadotrophin injection didn't influence microtubular spindle formation, but 5- or 15-IU hCG, 15-IU PMSG, or PMSG and hCG injections induced aberrant cortical granule (CG) and microfilament distribution. After 15-IU hCG or PMSG and hCG injections, fewer oocytes had enriched cortical actin domains, and the expression of alpha-, beta- and gamma-actin genes was greatly increased. In conclusion, a high dose of gonadotrophins alters the microfilament and CG distribution, which in turn reduces the developmental competence of oocytes. Injecting a reduced dose of PMSG to initiate ovarian hyperstimulation without triggering ovulation contributes to the efficient retrieval of developmentally competent oocytes.
Lee
Seung Tae
ST
Department of Food and Animal Biotechnology, Seoul National University, Seoul, Korea.
Han
Ho Jae
HJ
Oh
Seo Jin
SJ
Lee
Eun Ju
EJ
Han
Jae Yong
JY
Lim
Jeong M
JM
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D006224:Cricetinae; D003599:Cytoskeleton / Q000378:metabolism*; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006801:Humans; D008297:Male; D008647:Mesocricetus; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D010053:Ovary / Q000166:cytology / Q000502:physiology*; D010062:Ovulation Induction; D011247:Pregnancy
D000199:Actins; D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine