Serum gamma-globulin concentration in different stages of sexual activity in females of common vole, Microtus arvalis, Pall.

1. In young and adult females of common vole low gamma-globulin levels at the greatest individual variability in the estrous phase were observed. 2. In natural population when the nonactive females were probably not under hormonal suppression (northern Poland, late summer) they had significantly higher level of gamma-globulins than pregnant, lactating and post partum ones. 3. It is suggested that decreases of gamma-globulin concentration may be an important physiological consequences of hormonal events and influence the viability of females in natural population during reproduction period.