Histomorphology of prepuberal ovaries in the South American fur seal ( Arctocephalus australis Zimmerman, 1783)

Abstract

The South American fur seal reproductive histophysiology is scarcely described. This study provides a histological description of prepuberal South American fur seal (Arctocephalus australis) ovaries as well as three-dimensional reconstructions of subcapsular crypts and primordial follicles. Ovaries from fresh dead animals were processed for histology and sliced into serial sections. A portion of the superficial cortex was photographed, and the images were processed using BioVis3d software in order to generate 3-dimensional reconstructions. A. australis prepuberal ovaries conform to the basic structure of pinnipedian species, with a subcapsular crypts system made up of interconnecting cisternae and tubules with multiple openings to the surface. Generally, the primordial follicles were arranged in a monolayer beneath the tunica albuginea and were closely associated with subcapsular crypts. The large number of interstitial cells distributed throughout the cortex was the main histological feature in comparison with previous reports in other seals. Three-dimensional reconstructions modelled the subcapsular crypts microarchitecture and showed the close spatial relationship between the crypts and the primordial follicles. Despite the fact that the general ovarian histological structure was similar to that of other pinnipeds, the large number of interstitial cells is a distinctive feature that raises the question about the origin and function in A. australis with regard to the steroidogenic activity reported in other seal species.