Seasonal and age-related changes in the micro-anatomy of the prostate gland of the Subantarctic fur seal, Arctocephalus tropicalis

The prostate glands of male Subantarctic fur seals Arctocephalus tropicalis, taken at Gough Island (40 degrees 20'S, 09 degrees 54'W) between November 1977 and October 1978, were examined. Significant changes in the mass of the prostate, the diameter of the alveoli and height of the secretory epithelium precede the breeding season and support the fact that A. tropicalis is a seasonal breeder. Peak activity of the prostate is reached during November-January. We propose that seasonal changes in the prostate gland, and in male reproductive activity in general, may be cued by changing photoperiod. Micro-anatomical features of the prostate of the male Subantarctic fur seal differ between different age groups. Peak prostate mass, alveoli diameter and secretory cell height indicate that Subantarctic fur seal males reach full adulthood at 10-11 years of age.