Quantitative studies on spermatogenesis in the albino rat. II. The duration of spermatogenesis and some effects of colchicine

Abstract

Colchicine arrests spermatogonial cell divisions in metaphase. From the number of metaphase figures accumulated in 6 hours after application of the drug it can be calculated that the duration of a spermatogonial mitosis is 48 minutes. Knowing the duration of one cell division, the avg. no. of spermatogonia in 100 tubular cross sections and the avg. no. of mitoses normally found among these cells (mitotic index 0.83), it can be calculated that the duration of one "spermatogenic wave" is 4 days and the duration of a spermatogenic cycle 16 days. A critique of the data and the reasoning leading to this estimate is given. The meiotic divisions of the spermatocytes are not appreciably affected by treatment for 6 hours with doses as high as 4.5 mg. of colchicine per 1000 g. body weight. After 24 hours all meiotic figures are abnormal but arrest in metaphase is still not complete. Colchicine accentuates the normal periods of spermatogonial proliferation by causing an accumulation of mitotic figures and brings out clearly the presence of 5 peaks of mitotic activity. The 1st occurs at the beginning of the spermatogenic wave, the 2d approx. 24 hours later, the 3d to 5th follow at fairly regular intervals of 12 hours or somewhat longer.