Structure and possible functions of the calcospherite-rich cells (R* cells) in the digestive gland of the shore crab Carcinus maenas.
R*-cells of the digestive gland of Carcinus maenas have been investigated functionally and morphologically. A comparison of the capacity of separated cell suspensions to synthesize glycogen gave support to the hypothesis that R and R* cells belong to the same cell line. The unexpected observation of R* cells in gastric juice suggests that their release could represent a mode of redistribution of carbohydrate stores when the feeding activity of the crab is lower. Under electron microscopy, the calcospherites of R* cells appeared to be surrounded by multiple membranous layers, and displayed tubular and vesicular structures in their core. High glucose-6-phosphatase (G6Pase) activity in the subcellular fraction that is enriched in calcospherites suggests that these membranes are derived from the endoplasmic reticulum, via a process in which the enzyme plays a key role. We propose that this is the way by which the R cell differentiates into R* cell.
Loret
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SM
Département de Biologie, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
Devos
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PE
D000818:Animals; D003386:Brachyura / Q000033:anatomy & histology* / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D004064:Digestive System / Q000166:cytology*; D004068:Digestive System Physiological Phenomena; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis; D008297:Male; D008854:Microscopy, Electron
D006003:Glycogen; D005952:Glucose-6-Phosphatase; D002118:Calcium