ABSTRACT
Mink blastocysts grew in vitro when the culture medium contained estrone or ergosterol, but the growth was slow and of short duration, and believed to be the product of fluid uptake rather than cell proliferation.
Ergosterol failed to shorten the gestation period when administered to mink during the delay phase of pregnancy, the same failure having been reported earlier with estrogen.
Mink blastocysts did not grow in vitro in medium containing other vitamins, enzymes known or suspected to be present in uterine fluids, a variety of energy sources, rabbit uterine or blastocyst fluids or when transplanted to the uterus of 3-to 4-day pregnant rabbits.
A factor inhibiting blastocyst growth is believed to exist in the mink because rabbit blastocysts cease growing and collapse when retained in culture medium whose mink serum component is 5% or higher. Dialysis does not remove the factor.
Collapsed mink blastocysts can reconstitute to their original fluid-filled state in vitro.
