Male Reproductive Hormones
Sex differentiation and reproduction in male vertebrates are regulated by several different peptide and steroid hormones from various endocrine organs. In the closely related crustaceans, the androgenic gland appears to be unique, since this single gland regulates both male sex differentiation and male reproductive physiology and since, unlike in vertebrates, the endocrine and gametogenic functions are clearly separated into distinct organs, the androgenic gland and the testis, respectively. The regulation of reproduction in crustaceans is highly diverse; most species are dioecious, but there are also many hermaphroditic species. A number of studies indicate that the arthropod molting hormones are important regulators of female reproduction in crustaceans. Methyl farnesoate also acts as a sex determinant. In Daphnia magna, application of physiological amounts of exogenous Methyl farnesoate to egg-maturing females resulted in all-male broods. Protein blotting experiments with polyclonal antisera raised against androgenic gland hormone indicated the presence of a larger, biologically inactive protein.