Calcium distribution during egg development in Calliphora vicina

Calcium distribution during egg development in Calliphora vicina has been measured by atomic absorption spectroscopy. When female flies are fed meat, their calcium content rises and then remains stable throughout egg development. As the ovaries accumulate calcium, there is a corresponding decrease in the calcium content of the Malpighian tubules but not in any other tissues. Tracer studies with ⁴⁵Ca indicate that calcium absorption and excretion continue throughout much of the egg cycle.

It is concluded that calcium absorption by female meat-fed flies exceeds the demands of the developing ovaries, and that appreciable amounts of calcium are excreted by the Malpighian tubules. In addition, the tubules may store calcium for later movement to the ovaries. Some of the practical problems associated with demonstrating such a storage role for the Malpighian tubules are discussed.