AbstractThe relationship between the Sertoli cell counts, some measurable parameters of the seminiferous tubules and the dimensions of the Sertoli cell nuclei were examined in both normal and degenerate testes. Highly significant differences were found between rams in the numbers and in the dimensions and volumes of the Sertoli cell nuclei and in the diameters of the seminiferous tubules. The Sertoli cell counts were corrected for the differences in nuclear volume by dividing the count by the calculated nuclear volume. The Sertoli cell counts were corrected for changes in the area of the seminiferous tubule wall by multiplying the count by the square of the tubule radius. Correction for either nuclear volume or tubule area alone increased the differences between the Sertoli cell counts, but a simultaneous correction for both factors equalized the counts so that there were no significant differences between rams in the number of Sertoli cells per tubule cross‐section. It was concluded that, in normal and degenerate ram testes, counts of the Sertoli cell nuclei in the seminiferous tubule cross‐sections, when corrected for differences in nuclear volume, would provide a valid basis for comparing volume‐corrected counts of spermatogenic cells in different animals and in different treatments.