Developmental potential of artificially produced chimeric embryos following transfer to surrogate Goats

Abstract

An experiment was conducted to study the developmental potential of goat chimeric embryos. A total of 8393 mature oocytes were randomly divided into two groups. Gr 1: oocytes (n=5222) were activated with 5 μM calcium ionophore for 5 to 7 min followed by treatment with 2.0 mM DMAP (dimethylaminopurine) for 4 h in mCR2 aa (modified Charles Rosenkrans 2 amino acid) medium. Gr 2: oocytes (n=3171) were used for in vitro fertilization (IVF). Inner cell mass from hatched blastocysts of parthenogenetic activated embryos were used to produce embryonic stem cell-like cells while 2 cell embryos obtained from IVF were utilized to produce tetraploid embryos. Aggregation efficiency, compact morula and blastocyst formations were 84.93±8.13, 80.53±10.55 and 7.05±3.08%, respectively. A total of 47 chimeric goat embryos were transferred into 17 Sirohi female recipients, resulted in in vivo development of foetus in two recipients. In first recipient, foetus looked like a very thick and hyperechoic amniotic ring until 49 days; thereafter, it was completely resorbed. In second recipient, foetus and amniotic ring were visible as hypoechoic structure from 50 days onwards; thereafter it was completely resorbed at 58 days of embryo transfer. In conclusion, the study indicated that foetal resorption was observed at various stages of pregnancy after transfer of chimeric embryos into recipients. It appears that placental atrophy may be the principal cause of the loss of foetuses.