Development and maturation of canine oocytes: roles of ovarian and oviductal environment in the acquisition of developmental competence

The female reproductive biology of the domestic dog is distinct from that of other mammalian species. Notably, female dogs ovulate immature oocytes that require a prolonged period within the oviduct to complete maturation. As a result, developing an effective in vitro oocyte maturation system for this species has proven challenging. Research efforts have focused on elucidating the mechanisms that regulate dog oocyte maturation. Current findings indicate that factors present in the follicular and oviductal environments play critical roles in the acquisition of developmental competence of dog oocytes. This review explores potential mechanisms regulating dog folliculogenesis and oogenesis and highlights the contributions of the ovarian and oviductal environments to the developmental competence of the gamete.