The cloacal gland--an external indicator of testicular development in coturnix.

The quantitative relationship between cloacal gland size and testes weight during the stages of initial growth, involution and recrudescence is described. Cloacal gland foam was found to be a reliable indicator of testes size and function. The mean testes weight associated with the first presence of cloacal gland foam was 377 mg. and this occurred at a mean age of 29 days. The physical measurement of the cloacal gland provides a valuable noninvasive method of predicting testicular activity especially suited for long term experiments involving multiple measurements where a few coturnix may be used repeatedly (as their own control) rather than periodic killing of a large group of animals.