ISSN:
1432-0878
Schlagwort(e):
Posterior caeca
;
Gut
;
Calcium transport
;
Epithelial transport
;
Orchestia cavimana
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Medizin
Notizen:
Summary During molting, the epithelium of the posterior caeca (PC) of the midgut in the terrestrial crustacean, Orchestia cavimana, is active in calcium turnover. In the preexuvial period, epithelial cells that progressively differentiate into cell-type III secrete ionic calcium (originating from the old cuticle) from the base to the apex of the cell within a typical extracellular network of channels; the calcium is then stored in the PC lumen as calcareous concretions. Immediately after exuviation, the epithelial cells rapidly differentiate into cell-type IV, reabsorbing calcium from the concretions through successive generations of spherites which quickly appear, grow, and then disappear from the apex to the base of the same extracellular network. The PC epithelium is thus alternatively calcium-loaded and unloaded. When the calcium-reabsorbing process is complete (average 48 h after exuviation), the epithelial cells again differentiate into two different regional cellular types (cell-type I in the distal segment and cell-type II in the proximal segment) characteristic of the intermolt period. The dynamic changes in the PC epithelium during the postexuvial period are discussed, including the characteristic features of cell-type IV and of the reabsorption spherites.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00225566
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