The effect of strain of donor eggs, culture conditions, and experimental protocol on release of eggshell calcium by the chick chorioallantoic membrane in vitro

Abstract

Factors affecting release of calcium by the chick chorioallantoic membrane in vitro were assessed by culturing explants of shell with and without the chorioallantoic epithelium. Explants were removed from eggs on day 16 of incubation and cultured using techniques similar to those used to examine resorption of bone in vitro. The region of an egg from which an explant is removed, the strain of donor eggs used, and addition of bovine serum albumin to the culture medium did not affect release of calcium. In contrast, exposure of explants to a variety of different culture media (DMEM, Medium 199, BGJb, and RPMI) introduced considerable variation in calcium release. Calcium release in vitro was also examined by removing the blunt end of a fertile egg as well as the embryo and yolk. The remaining preparation was filled with culture medium, covered, and cultured for two 24-h periods, with a change of medium after the first 24 h. Preparations from which the chorioallantoic membrane had been removed released very little calcium during culture, whereas those with the epithelium in place released considerable quantities. However, release of calcium by preparations with the membrane declined during the second interval. When surface area is taken into account, such preparations mobilize less calcium than explants cultured under similar conditions.