Retinoic Acid Signalling and the Control of Meiotic Entry in the Human Fetal Gonad
Figure 1
Expression of genes encoding retinaldehyde dehydrogenase enzymes in the human fetal gonad.
qRT-PCR analysis reveals developmentally regulated expression of ALDH1A1 (A) in the human fetal testis, with transcript levels increasing significantly between 8–9 weeks gestation and 14–16/17–20 weeks gestation (ANOVA; a,b,c; p<0.05, n = 5–6 per group). Expression was not significantly different between gonads of different sexes at the same developmental stage, not between ovaries at different gestational ages. ALDH1A2 expression (B) is also developmentally-regulated in the human fetal testis, with transcript levels in the first trimester (8–9 weeks gestation) testis significantly higher than those in the early second trimester (14–16 weeks) testis (a vs b, p<0.05) and the late second trimester (17–20 weeks) testis (a vs c, p<0.01). Expression in the testis at 8–9 weeks gestation was also significantly higher than that in the fetal ovary at the same developmental stage (a vs d, p<0.05). ALDH1A2 transcript levels were also higher in the 8–9 week human fetal testis than in mesonephroi from age-matched fetuses (a vs e, p<0.01), which contrasts with the mesonephric-specific expression of Aldh1a2 in the mouse at a comparable developmental stage. No differences in the expression of ALDH1A3 (C) were detected between samples of different gestational ages of the same sex, or between the gonads of different sexes at the same developmental stage. 8–9, 14–16 and 17–20 denote the gestational age (in weeks) of specimens, meso: 8–9 week mesonephroi (pooled male and female). Values denote mean ± s.e.m..