The hatching gland cells of trout embryos: characterisation of N- and O-linked oligosaccharides

A histochemical, light and electron microscopy study of the hatching gland cells (HGCs) in incubated 50-d-old trout embryos is reported. The distribut ion of carbohydrate residues in the glycoconjugates of these cells was stud ied by means of a battery of 13 different lectins conjugated with horseradi sh peroxidase (PNA, ConA, LCA, WGA, SEA, UEA-I, HPA, DBA) or digoxigenin (D SA, MAA, AAA, SNA, GNA). Identification of N- and O-linked oligosaccharides in HGCs was performed by application of both chemical and enzymatic treatm ents. Present results suggest that HGCs are seromucous cells which store bo th high choriolytic enzyme (HCE) and low choriolytic enzyme (LCE), and that their cytoplasmic granules, endoplasmic reticulum and Golgi complex contai n additional sialic acid-rich glycoproteins. The negative charge of these g lycoproteins might be responsible for the rapid expansion of mucin to form a highly hydrated gel, which would facilite the action of these enzymes in programmed cell death and might play a major role during the morphogenic ev ents.