Efecto del cultivo in vitro y de la vitrificación de embriones en la supervivencia y desarrollo prenatal y crecimiento postnatal en el conejo

The use of assisted reproduction techniques in human medicine, as a response to fertility problems, as well as in animals, as a means of disseminating genetic improvement and preservation of genetic resources, has increased over recent years. However, given that these are applied during early embryonic development and that this is a period that is sensibly critical, the environment, means and techniques used can cause alterations in development that could leave a permanent mark on the individual conceived. The objectives of this study had been to evaluate the effects of in vitro culture and vitrification at different embryo stages on prenatal survival and prenatal and postnatal development. M199 medium was used for embryo culture and a vitrification two-step procedure was used in in the addition of cryoprotectants (20 and 40 per cent (v-v), ethylene glycol and 18 per cent (w-v) Ficoll) in Cryotop device. The study was divided into three experimental blocks: 24-hour embryo culture effect, 48-hour embryo culture and vitrification effect and 76-hour embryo culture and vitrification effect. A total of 1031 embryos from superovulated donors were transferred and a total of 50 transfers were made. Both culture and vitrification induced a delay in early embryonic development that resulted in lower embryonic and fetal survival rates, more apparent as earliest embryo development-stages were used. Prenatal development monitored by ultrasound scanning throughout pregnancy allowed to observe a delay in fetal and maternal placenta and fetal growth in 24-hour and 48-hour embryo cultured, and 48-hour embryo cultured and vitrified that were compensated from day 21. In contrast, vitrification of 76-hour embryos did not alter fetus or placentas growth throughout the gestation. Nineweek kits from 48-hour embryo vitrified and cultured group showed a greater body weight. However, no alteration in postnatal development caused by 24-hour embryo culture or 76-hour embryo culture and vitrification was observed.