High choriolytic enzyme gene expression during development. Embryos of various stages were hybridized with a high choriolytic enzyme probe. The yolk was removed before the color reaction. A Stage 20–21 (5 somite) embryo. B Stage 22 (lens formation) embryo. C Stage 23 (just before the start of heart pulsation) embryo. D Stage 25–26 (beginning of vitelline vein circulation) embryo. E Stage 28 (pigmentation of retina) embryo. F Stage 32 (completion of somitogenesis) embryo. G Stage 34 embryo. H Stage 35 (opening of mouth) embryo. I Stage 39 (just before hatching) embryo. J 2-dph larva (yolk not removed). Scale bars, 250 μm. From Inohaya et al. (1995).