EFFECT CULTURE CONDITIONS, DONOR AGE, AND INJECTION SITE ON IN-VITRO DEVELOPMENT OF DNA MICROINJECTED PORCINE ZYGOTES

A series of experiments evaluated development of porcine zygotes micro injected with DNA in three culture media and two incubation temperatur es, from postpubertal and prepubertal donors, and between zygotes inje cted with DNA into the pronucleus and the cytoplasm. Zygotes recovered from 36 postpubertal gilts in Exp, 1 were injected and cultured in mo dified NCSU-23, modified NCSU-37, and CZB media at 37 degrees C or 39 degrees C for 7 d. In Exp. 2, zygotes were collected from postpubertal or prepubertal gilts, microinjected with DNA, and cultured in modifie d NCSU-23. In Exp. 3 superovulated prepubertal gilts had DNA injected into the cytoplasm or pronucleus of zygotes. Mean percentages developi ng to the expanded or hatched blastocyst stage in modified NCSU-23 (42 .9) and modified NCSU-37 (40.1) did not differ, but development was gr eater than that for zygotes cultured in CZB (8.8; P < .05). Developmen t was greater at 39 degrees C (P < .05) than at 37 degrees C (36.5 vs 24.6%). Microinjection of DNA decreased development (P < .05) from tha t of noninjected controls (18.1 vs 43.1%). Zygotes from postpubertal g ilts had a higher percentage (68.0) of expanded and hatched blastocyst s than zygotes from prepubertal donors (29.0; P < .05). No development difference Was found between DNA injection into the pronucleus (23.1% ) or cytoplasm (17.4%), but development was less than for control embr yos (64.9%; P < .05). DNA microinjected porcine zygotes can be success fully cultured to the expanded blastocyst stage in modified NCSU-23 an d modified NCSU-37 media at 39 degrees C. Microinjection of DNA decrea ses survival of embryos from prepubertal donors more than it decreases survival of embryos from postpubertal donors.