EN
The hatching of embryo fish is a biochemical-mechanic process. In the final stage of embryogenesis the specialised hatching gland cells of the embryos secrete specific proteinase named a hatching enzyme or chorionase, which partially digests the multilayered egg envelope surrounding the embryo. The remaining parts of the envelope are ruptured by energetic movement of the embryo, which then emerges and starts an independent life. Present paper reviews the recent literature on the properties of hatching enzyme of various species of teleost embryos. It also contains a review of literature on the influence of environmental factors on the secretion and activation of this enzyme.