Spermatogenesis in the human infertile male.

The different cellular stages of the spermatogenic cycle in man were identified and categorised from the array of cells observed in preparations obtained from whole tubules of the testis. This included description of meiotic figures. An attempt to establish the dynamics of the spermatogenic process was then made by two complementary approaches. Experimental work, initiated to establish and maintain differentiation in tissue culture, was successful. In vitro labelling with tritiated thymidine identified S phase spermatogonia and S phase primary spermato- cytes and followed the fate of these cells. At ten days, labelled primary spermatocytes were distinguishable from labelled spermatogonia and at 10-12 days a surge of unlabelled primary spermatocytes, identified at diakenesis, was observed. Changes in cell category frequencies were recorded with time in tissue culture and between individuals. Cell category frequencies were also studied in a series of infertile males. This revealed very considerable variation, with some categories not represented in some individuals. Significant relationships were found between some cell categories in the series. These trends allowed the cell categories to be assigned to the sequence of events within the spermatogenic cycle with some confidence. Reasons were given for assigning differences in cell category frequencies to a rate effect due to a combination of cell division events and the proportional duration of each cell stage. Previous models of spermatogenesis have concentrated on multiplication due to division to explain ratios between cell categories. One cell category was a particularly important factor for describing the activity of the germinal epithelium. A practical method of identifying points of lesion in the infertile spermatogenic cycle was described and compared with established methods for expressing the status of the infertile testis.