Normalisierung der geschlechtlichen Entwicklung kopfloser Fragmente junger ♀♀ von Platynereis dumerilii (Polychaeta) durch Behandlung mit konservierten Prostomien juveniler Individuen

Abstract

Fragments taken from female Platynereis dumerilii are, at an early stage, characterized by small oocytes, unable to develop normal eggs and to complete the epitokous state if deprived of hormone supply from the prostomium. The question remained whether this inability to achieve normal sexual maturity is due to complete lack of common "juvenile brain hormone" or to absence of a special phase-specific "maturation hormone" whose existence has not yet been proved, but suggested on the basis of autoradiographic investigations of neurosecretory brain activity (Müller 1973). New experiments on such fragments demonstrate that fairly normal oogenesis can be induced and a more advanced epitoke formation attained by daily external treatment with dried isolated prostomia taken from juvenile specimens. Thus, there is no need to assume interference of a special "maturation hormone" in sexual development. The treated fragments show normal posterior regeneration followed by fairly normal sexual maturation, even if the supply of "juvenile brain hormone" is not changed throughout the experiment; hence it may be postulated that the fragment itself gradually alters its mode of response to the hormone. © 1974 Biologischen Anstalt Helgoland.