title: [Ultrastructural observations of follicular oocytes inseminated in vitro in squirrel monkeys (Saimiri sciureus)].
abstract: The ultrastructure of squirrel monkey (Saimiri sciureus) follicular oocytes inseminated in vitro was studied at the Endocrine Research Center of Michigan State University in the United States. Adult female squirrel monkeys were induced to ovulate with FSH-hCG, followed by laparoscopy 16 hours after hCG to collect ovarian follicular oocytes. A total of 45 oocytes were inseminated 21 hours after recovery by adding sperm collected by electroejaculation, followed by insemination culture for 24 hours. Inseminated oocytes were examined by light microscopy and transmission electron microscopy. Only three (6.7%) of inseminated oocytes were judged to be fertilized morphologically, but no sperm remnant was found in the cytoplasm of the oocytes. Fifteen (33.3%) had reached the second metaphase stage. As a whole, the maturation rate was 40%. Ultrastructurally, acrosome reacted sperm were observed in the cumulus cell layer, confirming the occurrence of sperm capacitation in the in vitro culture system. Cortical granules were seen throughout the cytoplasm of the germinal vesicle oocyte, especially in the vicinity of the Golgi complexes, suggesting the possibility that cortical granules originate from Golgi complexes. Metaphase chromosome, first polar body and cortical granules were observed at the second metaphase oocyte. Of three oocytes judged to be fertilized, one oocyte contained six pronucleus-like structures and another oocyte contained a pronucleus supposing fusion of two pronuclei (syngamy). But the ultrastructural morphology of a normal appearing fertilized oocyte could not be obtained. The possible cause of the low fertilization rate in the present study is supposed to be the poor follicular response and the prematurity of the cytoplasm due to repeated administrations of exogenous gonadotropins.
authors.affiliation: Department of Obstetrics and Gynecology, Asahikawa Medical College.
authors.forename: Y
authors.initials: Y
authors.lastname: Yorozu
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D005260:Female; D005307:Fertilization in Vitro; D008297:Male; D008854:Microscopy, Electron; D009865:Oocytes / Q000648:ultrastructure*; D012453:Saimiri; D013075:Sperm Capacitation; D013077:Sperm Head / Q000648:ultrastructure; D013082:Sperm Tail / Q000648:ultrastructure