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Formation of the inner branchiostegal cuticle of the blue crab, Callinectes sapidus
Author(s) -
Elliott E.A.,
Dillaman R.M.
Publication year - 1999
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/(sici)1097-4687(199906)240:3<267::aid-jmor5>3.0.co;2-8
Subject(s) - callinectes , cuticle (hair) , biology , ecdysis , arthropod cuticle , anatomy , ultrastructure , cuboidal cell , epithelium , microbiology and biotechnology , crustacean , moulting , botany , insect , zoology , genetics , larva
The noncalcified inner branchiostegal cuticle, which lines the branchial chamber, was examined histologically and ultrastructurally over the molt cycle in the blue crab, Callinectes sapidus. In intermolt crabs (stage C 4 ) the epithelium underlying the inner cuticle is cuboidal and has abundant intercellular spaces and a prominent basement membrane. Apolysis occurs at stage D 0 and dissolution of the cuticle is accompanied by the formation of numerous lysosomes in the epithelium. During stage D 1 , cells increase in height, apical mitochondria become more abundant, and the cuticle continues to be resorbed. An epicuticle is formed in early D 2 , arising from a fusion of small subunits apparently attached to short apical microvilli. Cuticle deposition continues through D 2 and is complete by stage D 3 . By the time cuticle deposition is complete, the epithelium has become extremely columnar and cells are filled with bundles of microtubules. In stage D 4 , an amorphous electron‐dense core appears in the microtubule‐filled cells, which are attached to the cuticle at their apical end and anchored to their basement membrane at the basal surface. These microtubule‐filled cells persist through ecdysis, stage E, but during stage A 1 the cores disappear and some organelles begin to reappear in the cytoplasm. By stage A 2 , the cells return to the cuboidal morphology seen in intermolt and remain so throughout the remainder of the molt cycle. This new pattern of cuticle deposition resembles that observed in the gills of crustaceans in that the cuticle is uncalcified and there is no postecdysial cuticle formation. However, instead of apolysis being delayed until just before ecdysis, the inner cuticle is formed during the first half of premolt, allowing the epithelial cells time to differentiate into a morphology that provides tensile strength for the stress of ecdysis. These new observations demonstrate that cuticle formation can follow very diverse structural and temporal patterns. In order to integrate and coordinate these diverse patterns, it is suggested that a suite of feedback mechanisms must be present. J. Morphol. 240:267–281, 1999. © 1999 Wiley‐Liss, Inc.