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Histochemistry of the developing alimentary tract of the Pacific big skate Raga binoculata Girard Evans, Robert E.

Abstract

The histochemical patterns of leucine naphthylamidase (LNAase) and alkaline phosphatase (AP) activity have been studied in the developing alimentary tracts of embryos (20 mm. - 200 mm.) of the skate Raja binoculata Girard. The enzyme(s) LNAase was found only in the spiral valve mucosae possessing elongated adult-like villi. The activity level increases with the growth of the embryo. The enzyme(s) is probably not related to differentiative events of the spiral valve but rather a manifestation of a particular stage of functional differentiation. Several possible physiological functions of the enzyme(s) are discussed. The enzyme AP had a more general distribution. It was found in many differentiating regions of the digestive tract. Activity levels which were generally high in undifferentiated mesenchymal tissue, decreased with further differentiation in some tissues. In other regions where AP remained in the adult, the enzyme accumulated with advancing differentiation. The significance of AP in the various localizations is discussed. AP isozyme patterns during alimentary tract development were studied using polyacrylamide gel electrophoresis. These data were correlated with the histochemical localization of the enzyme activity. It appears that new molecular forms of AP arise during gut differentiation. The relationship between AP and differentiation is discussed and AP is related to specific function where applicable.

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