Altering the surface area available for transport of calcium from the eggshell does not affect calcium metabolism of chicken embryos

Abstract

The amount of contact between the chorionic surface of the chorioallantoic membrane and the inner aspect of the eggshell was reduced by causing formation of an extra air cell in chicken eggs on day 8 of incubation. This manipulation reduced the surface area available for transport of calcium from the eggshell to the embryo. Concentrations of calcium, magnesium, and phosphorus in serum were determined for embryos sampled on days 12, 15, and 18, and for hatchlings. Calcium, magnesium, and phosphorus content of residual yolks and yolk-free carcasses of hatchlings was also determined. The presence of an extra air cell did not lead to variation in any of these indices of calcium metabolism. One interpretation of these results is that embryos compensate for the reduction in surface area available for transport of calcium by increasing the transport of calcium across those areas of the chorioallantois that remain in contact with the eggshell.