THE HATCHING GLAND CELL OF CARP (CYPRJNUS CARPIO) EMBRYO

The hatching gland of the carp embryo was an unicellular gland. It originated from the ectoderm. The earlist stage at which the hathing gland cell (HGC) can be detected with PAS specific staining was the eye-pigmented stage. The HGCs were majorly located in the ventral part of the head and in the jointing region between head and yolk sac. Oringinally, HGCs were beneath the epidermal cells. During development, they migrated to the surface of the embryo. Based on observations with SEM and TEM, the epidermal cells in HGC region had two kinds of processes, one cockscomb-like and the other wartlike before and after the enzyme secretion. The former was present before and during the period of secretion; the latter appeared after the secretion period, and accounted for the movement of the epidermal cells in this region. HGCs were rich in RER, mitochondria, ribosomes and Golgi complexes in which the proenzyme granules were formed. After the period of enzyme secretion, HGCs still remained in the epithelium and gradully degenerated with the development of the embryo. However, they could still be seen 30 hours after hatching.