EFFECT OF HUMAN LEUKEMIA INHIBITORY FACTOR ON IN-VITRO DEVELOPMENT OFPARTHENOGENETIC BOVINE MORULAE

The present study was conducted to investigate the effect of human leu kemia inhibitory factor (hLIF) addition to synthetic oviduct fluid med ium (SOFM) supplemented with human serum (HS) on the development of in vitro matured and parthenogenetically activated bovine oocytes. The o ocytes matured for 30 h were exposured to ethanol (7%, 7 min) and cyto chalasin B (5 mu g/ml, 5 to 6 h). The treated oocytes were cultured fo r 5 d in SOFM supplemented with HS, and Day-5 morulae were cultured fo r 2 d in SOFM supplemented with HS and with or without hLIF (5000 U/ml ) to investigate the subsequent in vitro development to the blastocyst stage. Of the 1531 oocytes that were parthenogenetically activated, 5 92 (37.5%) cleaved to the 2- to 8-cell stage and 174 (13.8%) developed to the morula stage. The addition of hLIF at the morula stage resulte d in a significantly (P<0.01) higher rate of development to the blasto cyst stage in the medium with hLIF (55.9%) than without hLIF (28.9%). The mean cell number per blastocyst developed in the medium with hLIF was also significantly (P<0.01) higher than that developed in the medi um without hLIF. To evaluate the viability, 6 parthenogenetically deve loped blastocysts were transferred to 3 recipient heifers (2 embryos p er heifer), while in 2 other recipient heifers estrus was prolonged af ter transfer. The plasma progesterone levels of the 2 recipient heifer s at the 28th day after transfer were 8.1 ng/ml and 9.0 ng/ml, but pre gnancy was not observed by ultrasonic scanning. The present results in dicate that the addition of hLIF to in vitro-produced, Day-5 parthenog enetic bovine morulae significantly improves the subsequent developmen t to the blastocysts stage; however, the present method still does not promote for development of parthenogenetic fetuses in cattle.