IN-VITRO DEVELOPMENT OF EMBRYOS FROM SINCLAIR MINIATURE PIGS - A PRELIMINARY-REPORT

The goal of this project was to identify conditions that result in dev elopment from the zygote or the 2-cell stage Sinclair miniature pig em bryos to the blastocyst stage. Four media were selected, 2 that have b een shown to result in in vitro development in domestic pigs (Hepes bu ffered Tyrode's medium and Whitten's medium), 1 that is compatible wit h similar development in the cow (CR-1), and 1 that is compatible with development in the mouse (CZB). One- and two-cell stage embryos from Sinclair miniature pigs were flushed from oviducts in Hepes buffered T yrode's medium, allocated to 1 of the 4 media and cultured for 120 h. At the end of the culture period, embryos were morphologically scored and nuclei were counted. Morphology scores were lowest for Hepes buffe red Tyrode's medium but were not different for Whitten's medium, CZB o i CR-1. The highest (P < 0.07) number of nuclei was present in the ooc ytes cultured in Whitten's medium (21.3), with CR-1 (15.7) and CZB (16 .5) not differing significantly. Similar to the morphology scores, Hep es buffered Tyrode's medium resulted in the lowest number nuclei (5.5) . In a parallel experiment, domestic pig embryos were cultured in Hepe s buffered Tyrode's medium versus Whitten's medium. The domestic pig e mbryos, while also developing better in Whitten's Medium, developed be tter in the Hepes buffered Tyrode's medium than did the embryos from S inclair pigs. Thus, the Sinclair pig embryo develops best if placed in Whitten's Medium.