Extent of GFP expression in adult and pup testis tissues.

(A) GFP expression images of testis tissues, from 2.5 dppp and seven-week-old Acr-GFP mice, cultured for 5 weeks. (B) PAS staining images of testis tissues, from 2.5 dppp and seven-week-old Acr-GFP mice, cultured for 5 weeks. The dotted rectangular areas are enlarged on the right. (C) Adults and pups were compared on the basis of the extent of Acr-GFP expression scored (judged at culture week 5). Testis tissue fragments of Acr-GFP mice, 2.5–4.5 dpp and 7–8 weeks old, were cultured for five weeks. Adult and pup testis tissues were examined in a total of 34 and 39 tissue pieces in three culture experiments, respectively (means±s.d., P<0.025 (Student’s t-test)). (D) The frequency of seminiferous tubules containing differentiated germ cells. Adult and pup testis tissues were examined in a total of 32 and 36 tissue pieces in three culture experiments, respectively. Sections stained with periodic acid Schiff were examined and the number of seminiferous tubules containing differentiated germ cells (spermatocytes, round spermatids, and/or elongating spermatids) asa well as seminiferous tubules not containing them were counted in each tissue to calculate the percentage of spermatogenesis-positive seminiferous tubule (means±s.d., P<0.002 (Student’s t-test)). Scale bars, 1 mm (A); 100 μm (B).