Studies on the physiology of a shrimp, Metapenaeus sp. (Crustacea: Decapoda: Penaeidae). III. Composition and stucture of the integument

Abstract

Inorganic constituents comprised 38.7 % by weight of intermoult cuticle of which 98.5% was calcium carbonate. Chitin was 34.3% of organic constituents. No inorganic materials were resorbed from the cuticle prior to moulting, but there was a reduction of 39% in chitin-protein. Polarized light showed that the epicuticle contained vertical submicroscopic structures, while the procuticle consisted of fibrils parallel with the surface. Acid mucopolysaccharides could be detected histochemically in the epicuticle, but not in the procuticle which gave a green reaction with toluidine blue. During premoult the epidermal cells grew progressively taller and the new epicuticle and exocuticle were synthesized. Ductless tegumental glands and amoeboid cells containing high concentrations of acid mucopolysaccharides and calcium, with some glycogen, were present among the apices of the epidermal cells. The epidermis of early postmoult showed an accentuation of these premoult features. The sequence of events in the integument is similar to that of other Crustacea except that glycogen is not particularly abundant. The mucopolysaccharide-containing amoebocytes are believed to play a major role in cuticle formation.