Demonstration by organ culture of a cerebral hormone stimulating the secretion of testicular androgen in the oligochaete annelid,Eisenia foetida f. typica Sav.

Previous culture experiments revealed that, in reproductively active E. foetida, the central nervous sytem (CNS) produces a neurohormone necessary for the secretion of an androgen by testes. The tracing of the origin of this neurohormone has now been done by culturing in vitro ovaries and testes with different ganglia of the nerve cord. In the presence of cerebral ganglia (CG), the percentage of testes transformed into ovotestes was low (3%), while reaching respectively 32% and 17% in the associations with sub-esophageal ganglia (SEG) or ganglia of the male or female genital segments (GS ♂ or ♀). Only the neurohormone produced by CG was able to stimulate secretion of the testicular androgen, the existence of which was proved by previous experiments. The secretion of this androgen was enough to transform 28% of the ovaries into ovotestes. On the other hand, no masculinization of the ovaries was observed in the presence of various ganglia of the ventral nerve cord (SEG, GS ♂ or ♀). It appears, therefore, that the secretion of the testicular androgen is stimulated by the CG.