In Vitro Studies of the Fertilizing Ability of the Sperm from Adolescent, Adult and Aged Male Syrian Hamsters

Abstract

There are indications that the male reproductive system is adversely affected as the animal ages. Both behavioral and physiological characteristics are involved, though variation among and within species is considerable. In bulls there is a general slowing down in mating behavior after 5–6 yr but some bulls do continue mating until 15 yr (Bishop,1970). Successful conceptions after artificial insemination decrease significantly with increasing age in bulls (Bishop, 1964). In man a sexual peak is reached during the mid-teens; thereafter sexual activity gradually declines (Kinsey et al,1948) and the ease with which conception occurs decreases after age 25 (MacLeod amp; Gold, 1953). Success of crosses between male and female golden hamsters drops from 58% in young males to 26.9% in 15 mo males (Soderwall amp; Britenbaker,1955). When litter size from natural mating in rats was followed from male age 43d to 500d, the litter size peaked at 200d, then declined (Saksena et al,1979). The purpose of this study was to determine whether the fertilizing ability of the sperm per se is influenced by the age of the male. The results of in vitro fertilization by sperm from adolescent, adult and aged males plus results of natural mating (% successful conceptions and litter size) are described.