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 t he prostate, the diameter of the alveoli and height of the secretory epithe lium precede the breeding season and support the fact that A. tropicalis is a seasonal breeder. Peak activity of the prostate is reached during Novemb er-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 sea l 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.