Testis-testicular gland complex of two Tripterygion species (Blennioidei, Teleostei): differences between territorial and non-territorial males

The morphological differences between the testis and testicular gland of territorial and nonterritorial males of Tripterygion tripteronotus and T. delaisi were examined and correlated with differences in reproductive behaviour. In territorial males of both species the testicular gland is much more developed than in non-territorial males. Larger cellular and nuclear sizes in the territorial males indicate that the activity of the gland cells is enhanced. These cells contain SER, numerous lipid droplets and mitochondria with lamellar cristae. Absence of 3β-HSD activity at these sites points to lack of a steroidogenic potency. In both territorial and non-territorial fish, steroid-producing Leydig cells have been demonstrated in the connective tissue betweeen the testis and the testicular gland, and around the collecting sperm duct. In addition, 3β-HSD activity has been found in the scarce interstitial Leydig cells of territorial fish. Morphometric data indicate an enhanced activity of the Leydig cells in territorial fish.