Morphometric aspects of rat testis development.

A morphometric study of rat testis development and ageing (from 5 to 360 days of age) has been carried out. The testicular volume increases from 10.28 +/- 0.35 mm3 (5 days of age) to 1819.43 +/- 52.67 mm3 (360 days of age), showing the most rapid increase between 20 and 70 days of age (22.6 times). The mean tubular diameter increases from 62.25 +/- 1.50 micron (5 days of age) to 280.81 +/- 9.77 microns (360 days of age) and the tubular length from 2.74 +/- 0.18 m (5 days of age) to 25.45 +/- 1.76 m (360 days of age). Up to 15 days of age, the increase in testicular volume was mainly due to the increase in tubular length, whereas from this age onwards the tubular growth was similar in both length and diameter. Tubular development had nearly finished at 70 days of age.