Paracrine factors from cumulus-enclosed oocytes ensure the successful maturation and fertilization in vitro of denuded oocytes in the cat model.
OBJECTIVE
To better characterize cumulus-oocyte interactions during oocyte maturation and fertilization in the cat model.


METHODS
Experimental in vitro study.


METHODS
Smithsonian Institution.


METHODS
Domestic shorthair cats.


METHODS
Groups of denuded oocytes (DOs) and cumulus-oocyte complexes (COCs) were subjected to in vitro maturation (with or without FSH and LH, with or without the gap junction disruptor 1-heptanol, in separated groups or in coculture) and inseminated in vitro (IVF; in separated groups or in coculture).


METHODS
Nuclear maturation, pronuclear formation, kinetics of early embryo cleavage, and blastocyst formation and quality after different in vitro conditions were compared between DOs cultured separately and DOs cocultured with COCs.


RESULTS
Without FSH and LH, the removal of cumulus cells prevented spontaneous meiotic resumption in DOs. With FSH and LH, groups of DOs progressed to the metaphase I stage but fully advanced to metaphase II only in coculture with intact (nondisrupted) COCs. Groups of DOs cultured separately were fertilized poorly and exhibited no blastocyst formation. In contrast, DOs cocultured with intact COCs during in vitro maturation and IVF recovered fertilizability, and approximately 35% formed blastocysts.


CONCLUSIONS
Paracrine factors produced by cumulus-enclosed oocytes in the cat model will help to develop synthetic media for successful in vitro culture of DOs.
Godard
Natasha M
NM
Center for Species Survival, Department of Reproductive Sciences, Smithsonian's National Zoological Park, Washington, District of Columbia 20013-7012, USA.
Pukazhenthi
Budhan S
BS
Wildt
David E
DE
Comizzoli
Pierre
P
D000818:Animals; D002415:Cats; D018929:Cell Culture Techniques / Q000379:methods; D018920:Coculture Techniques; D003470:Culture Media; D054885:Cumulus Cells / Q000166:cytology / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D007044:Hysterectomy; D007986:Luteinizing Hormone / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010052:Ovariectomy; D011247:Pregnancy
D003470:Culture Media; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone