COMPARATIVE-ANALYSIS OF IN-VITRO DEVELOPMENT OF OUTBRED MOUSE EMBRYOSCULTURED IN KREBS-RINGER OR TYRODE-DERIVED MEDIA

Culture media for mouse preimplantation development are usually derive d from two basic solutions: Krebs-Ringer and Tyrode. We have used outb red mice (OF1) to make a comparative analysis of derived media of both types and their success in sustaining development from the one-cell t o the blastocyst stage. The best results (up to 50%), in terms of over coming the two-cell block and sustaining development to expanded blast ocyst, were obtained with media derived from Tyrode's solution and wit h Krebs-Ringer-based media in which the high concentrations of certain metabolites (Cl-, K+, Mg2+ and PO43+) were reduced to the values pres ent in the Tyrode-derived media. Interestingly, medium T6 (based on Ty rode and incapable of avoiding developmental block on its own), yielde d the best development rate with the addition of ethylenediaminetetraa cetic acid (EDTA). The addition of glutamine to medium T6 did not have any effect. We further developed T7, a medium based on T6 but incorpo rating the concentrations of nutrients present in the oviduct. This me dium also proved better than its Krebs-Ringer counterpart (MTF), but n ot better than T6, probably due to the different nutritive requirement s in the transition from morula to blastocyst. The two most significan t findings were: i) that Tyrode-based formulations were superior to me dia based on Krebs-Ringer solution, and ii) that medium T6 with EDTA w as as effective for mouse egg culture as the recently developed KSOM m edium.