DEVELOPMENT OF BOVINE MORULAE AFTER BISECTION AND BIOPSY AND ASSESSMENT OF DNA AMPLIFICATION BY THE POLYMERASE CHAIN-REACTION

Bovine morulae (n = 94; d 6-6.5) were collected non-surgically from su perovulated dairy cows (n = 22) to assess embryo viability in vitro af ter bisection or biopsy and compare the efficiency of polymerase chain reaction (PCR) amplification of 18S rRNA genes, high copy number gene s, from embryo biopsies and demi-morulae. Biopsies and one of each dem i-morulae pair were subjected to PCR while the biopsied embryo and rem aining demi-morula were cultured in vitro for 48 h. Development scores of 1 (degenerate), 2 (morula), and 3 (blastocyst) were assigned to em bryos at 24 and 48 h of culture. Mean development scores for biopsied embryos (n = 50) at 24 and 48 h were 2.4 +/- 0.1 and 2.3 +/- 0.1 (xBAR +/- SE) and did not differ from 24 h (2.3 +/- 0.1) and 48 h (2.4 +/- 0.1) mean development scores of bisected embryos (n = 44). Mean cell n umber after 48 h of culture did not differ between treatments with 41. 8 +/- 2.5 (n = 22) for bisected embryos and 48.8 +/- 2.9 (n = 29) for biopsied embryos. The endogenous 18S rRNA gene was detected in 78% (32 /41) of the demi-embryos and 81% (39/48) of the biopsies. These result s indicate that recovery of a biopsy has no advantage over removal of one half of the embryo with regard to subsequent embryo development an d DNA amplification using PCR. These procedures allow for simple tissu e collection for PCR without compromising subsequent embryo developmen t.