Fig. 5

A, B Evaluation of the proliferation activity (A) and of the proportions of spermatogonia (B) in zebrafish testes cultured for 4 days with 100 ng/mL Insl3, and in the absence or presence of the RA inhibitor DEAB (10 μM). C Ex vivo transcript levels of the RA producing (aldh1a2) and degrading enzymes (cyp26a1) in testis tissue incubated in the absence or presence of 100 ng/mL Insl3. Daldh1a2 and cyp26a1 expression levels in wild-type (insl3^+/+) and insl3 knockout (insl3^−/−) testes 9 and 12 months post-fertilization. E Read numbers (RNAseq) of RA metabolic enzymes in control, germ cell-depleted (by exposure to the cytostatic agent busulfan⁵¹), and testes with recovering (from busulfan) spermatogenesis, as described by Crespo et al.²⁵ (NCBI GEO data set GSE116611). In A, B and E, data are shown as mean ± SEM (A: N = 6; B: N = 4; E: N = 5; *p < 0.05; **p < 0.01), and in C, D as mean fold change ± SEM (C: N = 7; D: insl3^+/+ and insl3^−/− 9 months, N = 8 and 7; insl3^+/+ and insl3^−/− 12 months, N = 6 and 10; *p < 0.05) and expressed relative to the control group (which is set at 1). A_und, type A undifferentiated spermatogonia; A_diff, type A differentiating spermatogonia; B, type B spermatogonia.