Partial meiotic arrest in Prdm9-deficient PWD male mice. (A) Scheme of spermatogenesis. Prophase I proceeds from prepachytene (leptotene and zygotene) spermatocytes via DSB formation and DSB repair (yellow stars) accompanied by partial synapsis (green rectangles) to pachytene with full synapsis and the repair of some DSB(s) to crossover(s) and of the remaining to noncrossovers. (B) Spermatogenesis can progress beyond the spermatocyte (SC) stages to the spermatid (ST) stages in PWDtm/tm, but not in B6tm/tm males. The evaluation of sections from adult testes (C–H) stained with hematoxylin and eosin (H/E). The tubule types were sorted according to their most advanced cell type excluding spermatozoa. (C–H) Representative tubule sections (higher magnification in F–H compared to C–E). The blue and red arrows point to round and elongated spermatids, respectively; these cell types are absent from B6tm/tm.
