The Response of the Lamprey to Injection of Anterior Lobe Pituitary Extract

Abstract

1. Metamorphis could not be induced in the larvae in the Lampetra planeri by injection of anterior lobe pituitary extracts. 2. In both larval and adult animals the injections produced marked swelling of the cloaco and changes of body shape, these being secondary sexual characteristics which normally appear just before spawning. 3. The cloacal swelling was not accompanied by any detectable histological changes in the ovaries or in the majority of the testes examined, but in a few of the latter changes possibly indicative of abortive spermatogenesis were observed.