Strain differences in the concentration, motility and morphology of epididymal sperm in relation to puberty in mice.

Changes in the concentration, motility and morphology, of epididymal sperm have been evaluated in males of between 40 and 100 days of age in BALB, CBA, C3H and C57BL strains of mice. Particular attention was paid to sperm morphology, and a multiple entry classification system was used for its quantitation. At 40 days in each of the 4 strains studied sperm were few in numbers with poor motility and highly atypical morphology, particularly in the head region. From 80 days of age values for the 3 parameters were within the normal range. At equivalent ages during puberty the 4 strains differed in the concentration and motility of epididymal sperm, indicating difference in the time of onset of puberty between the strains. However, once adulthood was reached the strains differed only in the percentage of normal forms and in the frequency distribution of sperm with the various morphological abnormalities.