CYCLICAL CHANGES IN THE TESTICULAR ACTIVITY OF THE LAKE CHUB, COUESIUS PLUMBEUS (AGASSIZ)

Abstract

The cyclical changes in the activity of the testes of a teleost, the lake chub, from a north temperate latitude have been studied by histological and histochemical methods with a quantitative evaluation of the different spermatogenetic stages. The annual testicular cycle is divided into live stages and cyclical changes in the spermatogenetic activity have been related to the changing environmental factors, namely day length and water temperature. The annual cycle consists of a prolonged mitotic phase during the fall and winter, and a shorter meiotic phase during the spring. Lobule boundary cells have been examined and changes in their activity have been recorded. Continued spermatogenetic activity during spawning enables repeated spermiation, which is advantageous since the males are comparatively fewer than the females.