We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Trans-epidermal Transport and Storage of Calcium in Holthuisana transversa (Brachyura; Sundathelphusidae) During Premoult.
- Authors
Greenaway, Peter; Farrelly, Caroline
- Abstract
Holthuisana transversa reabsorbs much of its exoskeletal calcium in the last 3 days before ecdysis and stores it in circulating granules in the haemocoel and in non-circulating granules in the subepidermal connective tissue. Calcium enters the epidermal cells from the moulting fluid, probably through their apical microvilli and is either incorporated into intracellular calcium granules or exits the cell via the basolateral membranes to be used in formation of two other granule types. Intracellular granules (0.4-2 µm long) form in large masses in the apical cytoplasm ot the epidermal cells. They are formed as membrane-bound vesicles by the Golgi, and calcium and organic matrix material are added from the surrounding cytoplasm. As development proceeds, lamellae appear and calcium carbonate is deposited in the matrix. Granule masses move basally and are stored in the connective tissue. Calcium is also incorporated into extracellular large granules (0.8-3.8 µm long) which are formed in narrow Intercellular channels between epidermal cells. A third granule type (small granules, 0.26 µm diameter) is formed in subepidermal connective tissue cells and released into the haemolymph in very large numbers. Calcium was identified in the two larger granule types using X-ray microanalysis and significant amounts ot phosphorus and potassium were also present in the large granules. A model for ion cycling between the exoskeleton and granules is presented.
- Subjects
CRABS; SUNDATHELPHUSIDAE; ECDYSIS; CONNECTIVE tissues; ANIMAL morphology
- Publication
Acta Zoologica, 1991, Vol 72, Issue 1, p29
- ISSN
0001-7272
- Publication type
Article
- DOI
10.1111/j.1463-6395.1991.tb00313.x