Fig. 3.

Seminiferous cord/tubule sections of controls (A, B, E, H, K, N and Q), propylthiouracil PTU-(C, F, I, L, O and R) and T3-treated mice (D, G, J, M, P and S) killed between 1 and 100 days of age. Bar = 20 μm (A–J) and 40 μm (K–S). sc, seminiferous cords; st, seminiferous tubules; asterisk, lumen; arrows, Sertoli cells. The insert indicates the most advanced cell type: G, gonocyte; A₃, type A₃ spermatogonia; Pl, pre-leptotene spermatocyte; P, pachytene spermatocyte; Ar 1, step 1 round spermatid; Al 7/8, step 7/8 elongated spermatid; Al 13, step 13 elongated spermatid.