Expression of zebrafish cyp11a1 during embryogenesis. (A) RT–PCR analysis followed by hybridization of cyp11a1 in adult tissues and at various developmental stages: cleavage (1 to 128-cell), epiboly (sphere, 30, 50, and 70% epiboly), segmentation (12 and 18 hpf), pharyngula (24 hpf), hatching (48 hpf). RT–PCR of actin was used as RNA loading control. (B–L) In situ hybridization of cyp11a1: (B) in blastodiscs at the cleavage stage, (C–E) during epiboly below the blastomere extending from the animal pole toward the vegetal pole, (F) sections at 50% epiboly, (G) higher magnification of the square area in (F). (H–J) Expression of cyp11a1 in the yolk syncytial layer (YSL) persists at 20 phf. (I,J) Sections from (H). (K–L) Expression of cyp11a1 is located at a region ventral to the third somite at 36 hpf. Somite numbers are marked as 1, 2, and 3. (K) Lateral view, (L) ventral view.

Expression of zebrafish cyp11a1 in adult organs. (A) Whole-mount in situ hybridization of adult brain. OB, olfactory bulb; Tel, telencephalon; Hyp, hypothalamus; PG, preglomerular area; ON, optic nerve. (B,C) Ovary. (C) Section of (B). Expression of cyp11a1 is located in oocytes and the granulosa/theca cell layer. Arrow in (C) indicates granulosa/theca cell layer, and arrowhead the zona pellucida. (D,E) testis; (E) is a higher magnification of (D). Arrows in (E) indicate Leydig cells. Scale bar: 1 μm. (F) Northern blot analysis detects expression of cyp11a1 in adult ovary, stage V oocytes and early cleavage stage embryos.