Relative growth of the tendinal cell and muscle in larvalArtemia

Abstract

Summary Antennal tendinal cells of the brine shrimp Artemia are modified epidermal cells containing acentric bundles of microtubules and microfilaments that traverse the cell from the muscle insertion site on the basal surface to the cuticle on the apical surface. Morphometric determinations of growth of the antennal endite retractor muscle revealed that the muscle increased in length and width, and the nuclei replicated during the fourth instar. The attached tendinal cell, however, demonstrated no increase in the area of the microtubule- and microfilament-rich region or the apical surface, and the nucleus remained in G1, showing that muscle growth can occur without an equivalent increase in microtubules and microfilaments in the tendinal cell. The basal membrane associated with the muscle insertion site was the only region of the tendinal cell to increase in dimension. Expansion of this region preceded growth of the muscle, suggesting that interactions at the muscle insertion-tendinal cell junction may b...