Cleavage and Blastocyst Formation by Pig Eggs In Vitro2

Abstract

Pig eggs were cultured in modified Krebs-Ringer bicarbonate medium (modified KRB) which included some or all of the following; glucose (5.56 × 10⁻³M), lactate (25 × 10⁻²M), pyruvate (2.5 × 10⁻⁴M) and bovine serum albumin (BSA: 4 g/liter). In vitro development of one and two-cell eggs was limited and few cleaved beyond the four-cell stage. In contrast, eggs recovered at the four-cell stage cleaved and formed blastocysts at near the expected in vivo rate of development. More eggs cultured in medium without lactate and pyruvate formed blastocysts than when lactate and pyruvate were included (P<.01) and pyruvate alone inhibited development (P<.01). Four-cell pig eggs also formed blastocysts when only BSA was added to the inorganic salts in modified KRB. Transfer of eggs cultured 24, 48 or 72 hr to unmated recipient gilts resulted in 60% (60/100), 0% (0/22) and 19% (19/100) survival rates on day 21 to 30 of gestation, respectively. These results indicate the requirements of pig eggs are relatively simple from the four-cell to blastocyst stages since development can be supported by a bicarbonate buffered salt solution supplemented with either glucose and BSA or BSA alone. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science