ON THE HORMONAL CONTROL OF CELL DIFFERENTIATION IN THE OVOTESTIS OF SLUGS (GASTEROPODA: PULMONATA)

Abstract

If the tentacles of Arion ater and Milax sp. are cut off, the animals show an increased number of eggs after a period of 3 or more weeks. When extracts of the brain and tentacles are injected into the animals without tentacles, the number of eggs produced may approach that of the normal animal or it may be somewhat higher, depending on the relative amounts of the brain and tentacle hormones in the injected solution. This work supports the idea that there are two distinct hormones controlling the differentiation of the germ cells: one, in the brain, concerned with egg production; the other, in the tentacles, stimulating sperm. The two hormones form a balanced system in the normal animal with the tentacular hormone appearing first.