In vitro maturation of canine oocytes: a unique conundrum

Oocyte maturation depends on multiple variables. In fact, in dogs, the requirements for oocyte development in vitro are so complex that achievement of female gamete maturation has been viewed as a difficult problem. The conundrum, thus far unanswered, of achieving dog oocyte maturation in vitro, is nowadays the major puzzle of the in vitro program in the canine species. In in vitro studies of dog oocytes, researchers are dealing with an entire spectrum of reproductive functions, from oocyte maturation to development, which are not entirely understood for the canine species. There have been many trials focusing on animal selection, oocyte quality identification, establishment of environmental conditions, and medium composition. Different systems were tried but have not produced satisfactory results. Differences in metabolic requirements are considered to be some of the major causes underlying the specific sensitivity of the canine oocyte to in vitro development. The main aim of this review is to provide the reproductive biologist with information on the novel trials being performed in the field of in vitro assisted reproductive technology (ART) for canines. The article focuses on in vitro oocyte maturation.