Renewal of spermatogonia in man
Version of Record online: 3 FEB 2005
Copyright © 1966 Wiley-Liss, Inc.
American Journal of Anatomy
Volume 118, Issue 2, pages 509–524, March 1966
How to Cite
Clermont, Y. (1966), Renewal of spermatogonia in man. Am. J. Anat., 118: 509–524. doi: 10.1002/aja.1001180211
- Issue online: 3 FEB 2005
- Version of Record online: 3 FEB 2005
The spermatogonia of normal adult human testis were investigated in view of clarifying their mode of proliferation and renewal. Three main types of spermatogonia were identified: the dark type A spermatogonia (Ad) tentatively considered as the stem cells, the pale type A spermatogonia (Ap) and the type B spermatogonia (B), these being the more and more differentiated elements giving rise to preleptotene spermatocytes. The dark and pale type A spermatogonia were present in all stages of the cycle of the seminiferous epithelium, the type B spermatogonia were found in stages VI, I and II of the cycle and the preleptotene spermatocytes in stages III and IV of the cycle. The type A spermatogonia divided preferentially in stage V of the cycle and the type B spermatogonia in stage II of the cycle.
Quantitative data on spermatogonia and preleptotene spermatocytes revealed that the cell ratio Ad: Ap: B: Pl was equal to 1:1:2:4. This indicated that the spermatogonial stem cells divided to produce equal numbers of new stem cells (Ad) and of the more differentiated pale type A spermatogonia (Ap). Each one of the latter gave rise to two type B spermatogonia which in turn produced four spermatocytes.
The arrangement in pairs of the dark and pale type A spermatogonia throughout the duration of the cycle indicated that the mitoses of spermatogonial stem cells are “equivalent” in nature; therefore, the possibility of having “differential” mitoses to explain the renewal of spermatogonial stem cells should be abandoned. Lastly, the frequent arrangement of the two classes of type A spermatogonia in homogeneous clusters indicated that the impetus which facilitates the differentiation of stem cells into the more differentiated elements (Ap) may affect homogeneous and compact groups of stem cells.