The Postnatal Development of the Bovine Leydig Cell Population

Contents: The postnatal development of the bovine Leydig cell population from week 4 to young adulthood (75–100 weeks) was examined with morphometric techniques using perfusion-fixed samples and histological, semithin and ultrathin sections. Leydig cell mass per testis increases from 0.15 g to 3.62g between weeks 4 and 16, from 3.64 g to 5.93 g between weeks 20 and 30 and from 7.28 g to 10.47 g between 1 year and 1 1/2 to 2 years. Relative Leydig cell volume per unit is largest in week 16 (17.1 %). Calculated number of Leydig cells per testis amounts to 0.42 ± 10⁹ in week 4 and 6.02 ± 10⁹ in the adult group. Leydig cell nuclear diameter in week 4 (5.6 ± 0.3 pm) is significantly smaller and in week 75–100 (7.4 ± 0.4 μm) significantly larger than in weeks 8 through 52. Irrespective of varying Leydig cell size, the relative content of eR (about 48%) and mitochondria (about 8%) fluctuates in narrow limits during the entire period. The individual Leydig cell of week 4 has less than 20%, of week 8 about 30%, of weeks 16 through 52 about 50% of the volume of a Leydig cell of young adult (75–100 weeks) animals .