カイコのマルピギ管細胞の微細構造および変態にともなう変化

概要

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Ultrastructural research was carried out on the Malpighian tubule cells of larvae, young pupae and young adults of the silkworm. The larval tubules differentiate into two portions, a'coelomic' portion which excretes calcium oxalate as visible deposits, and a 'cryptonephric' portion whose function is to reabsorb water from the hindgut. These twe portions have a marked difference in morphology of their mitochondria. Nevertheless, they share a basic conformity in the general architecture of the cells, such as large and numerous mitochondria associated with the microvilli, and well-developed inflections of the apical and basal plasma membranes. Pupal Malpighian cells, on the contrary, lack these ultrastructural characteristics which are considered to be associated with the functions of transport and exchange. In the adult the cells again assume these characteristics. As visible excretory products, the larval tubule contains in its lumen many rectangular deposits of calcium oxalate, which are always found extracellularly. Contrary to this, pupal cells contain numerous intracytoplasmic globular calcospherites. They may be discharged into the lumen during the late pupal stage, since they are no longer observable in the adult cells. These findings suggest a "switching over" of the excretory mechanisms in the Malpighian cells during the larval-pupal transformation.
社団法人日本動物学会の論文
1974-06-25