Slug reproductive maturation hormone: In vivo evidence for long-day stimulation of secretion from brains and cerebral ganglia

Summary

Slugs (Limax maximus) that would normally remain reproductively immature in short-day light cycles (LD 8∶16) were employed as hosts for brain explants. Reproductive tract development was induced in hosts receiving whole brains from donors exposed to long days (LD 16∶8), but no development occurred in hosts receiving short-day brains (Fig. 1 and Table 1). Development equivalent to that induced by whole, long-day brains was also induced by implanting only cerebral ganglia from long-day donors (Table 2). Implantation of subesophageal complexes from long-day donors failed to stimulate reproductive organ growth but significantly inhibited somatic growth (Table 2). The results indicate that long-day photoperiods stimulate the release of a maturation-inducing factor from cells located in the cerebral ganglia of theLimax brain. It also appears that a growth-inhibiting factor is produced by the subesophageal ganglia.