title: Paracrine factors from cumulus-enclosed oocytes ensure the successful maturation and fertilization in vitro of denuded oocytes in the cat model.
abstract: 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.
authors.affiliation: Center for Species Survival, Department of Reproductive Sciences, Smithsonian's National Zoological Park, Washington, District of Columbia 20013-7012, USA.
authors.forename: Natasha M
authors.initials: NM
authors.lastname: Godard
authors.forename: Budhan S
authors.initials: BS
authors.lastname: Pukazhenthi
authors.forename: David E
authors.initials: DE
authors.lastname: Wildt
authors.forename: Pierre
authors.initials: P
authors.lastname: Comizzoli
mesh_terms: 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
chemical_list: D003470:Culture Media; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone