[Asynchronous development of the genital tract in the snail, Helix aspersa, during growth and reproduction].

During the growth of laboratory-raised Helix aspersa, the development of the albumen gland and spermoviduct was studied in relation to age, weight and different stages of reproduction such as mating and egg-laying. The results showed that the population can be divided into 2 categories because of different growth rates and asynchronous development of the genital tract. The fast-growing snails are larger and reach sexual maturity (female type maturity) in a shorter period than slow growing snails (male type maturity). During growth, the maturation of the genital tract was not directly proportional to the weight of the animal. Within each class of similar weight and age of population, 2 groups were identified; in one group, the genital tract was significantly less developed than in the other. This asynchrony of genital tract development could still be found between mating partners of the same weight, the genital tract could be 3 times smaller in one than in the other partner. However, this difference disappeared between mating and egg-laying. These observations suggest: that asynchronous development of the genital tract could be a strategy for the developing population of Helix aspersa; and that (a) mating factor(s) is (are) involved in the regulation of the growth and function of the genital tract.