FINE STRUCTURE AND HISTOCHEMISTRY OF PHARYNX AND HEPATIC CAECUM OF BRANCHIOSTOMA-LANCEOLATUM (PALLAS)

Cytochemical and ultrastructural studies have been carried out on the hepatic caecum, hyperpharyngeal groove and endostyle of Branchiostoma lanceolatum. The following enzymes have been demonstrated: acid and alkaline phosphatase, ATP-ase, aminopeptidase, α-naphthyl-acetate- and indoxyl-acetate esterase, glucosaminidase, arylsulphatase, NADH-and NADPH-diaphorase. The hyperpharyngeal groove proved to be particularly rich in enzymes. The epithelial cells of the hepatic caecum possess at their bases numerous lipid droplets and in the supranuclear cytoplasm granules which presumably contain digestive enzymes. The epithelium of the hyperpharyngeal groove is characterized by large basal vacuoles and apical secretion granules. The electron microscope confirms the existence of several cell zones in the endostyle. The cells of the esterase rich zones 2 and 4/5 possess a well developed system of granulated E. R. as well as globular inclusions which presumably represent mucus droplets. In zone 4 in addition a great number of lipid inclusions and specific electron dense secretion granules occur. In the acid phosphatase rich zones 1, 3 and 6 the cilia-bearing cells are arranged in typical columns. © 1969 Springer-Verlag.