TEMPORAL VARIATION AND SEXUAL DIMORPHISM OF THE SKIN OF PERCH PERCA-FLUVIATILIS L - A MORPHOLOGICAL-STUDY

Temporal variation and sexual dimorphism were found in the skin of the caudal fin of wild perch from the Baltic Sea. For most of the year males had thicker skin than females. Both sexes were found to have the highest recorded epidermal thickness in the pre-spawning period, indicating a relation with the reproductive cycle. However, the reverse pattern occurred in the dermis, i.e. an increased thickness in the post-spawning period. The study also demonstrated that temporal variation and sexual dimorphism of the epidermis were, at least partially, the result of variation both in the number and in the size of epithelial cells. Temporal variation of the cellular components was also found, with an increased prevalence of vesicle-containing epithelial cells during the pre-spawning period.