Effect of Testosterone Propionate on Regenerating Anal Fin of Adult Platypoecilus maculatus Females.∗

Summary Treatment of adult P. maculatus females with testosterone propionate, begun during the first 20 days of anal fin regeneration, produces an anal fin which is more male-like than that obtained by treatment of normal females but which differs clearly from the typical male gonopod. Beyond 20 days of regeneration the capacity for gonopod formation declines until, by the time the characteristic female form is attained, the capacity is no greater than in the normal adult female fin.