The morphometric changes in the gills of the estuarine crab Chasmagnathus granulatus under hyper-and hypo-regulation conditions are not caused by proliferation of specialised cells.

GENOVESE, G; LUQUET, C; PAZ, D; ROSA, G; PELLERANO, G.

JOURNAL OF ANATOMY

Blackwell

Lugar: Oxford; Año: 2000 vol. 197 p. 239 - 246

0021-8782

Chasmagnathus granulatus is a hyper-hyporegulating crab that inhabits changing habitats of salinity in Brazil, Uruguay and Argentina. Since the gills are the main sites for active ion transport in crabs, the adaptive changes in the gill epithelium occurring under different conditions of salinity were studied by means of morphological and morphometric analysis, and immunohistochemical identi®cation of cell proliferation (BrdU technique). In anterior (1±3) gills the epithelium thickness from crabs acclimatised to 12, 34 and 44 g}l ranged from 1±27 to 2±46 lm, with no signi®cant change during acclimatisation, thus denoting a respiratory function. Medial (4±5) gill epithelium was slightly thicker in extreme salinities, but these differences were not statistically signi®cant. In contrast, epithelial thickness of the posterior (6±8) gills increased signi®cantly up to 8±10 lm (dorsal zone of gill 8) both in hyper- and hyposaline media compared with seawater. The dark areas measured in gill 8 treated with AgNO$ revealed putative ion transporting tissue, especially at 12 and 44 g}l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.is a hyper-hyporegulating crab that inhabits changing habitats of salinity in Brazil, Uruguay and Argentina. Since the gills are the main sites for active ion transport in crabs, the adaptive changes in the gill epithelium occurring under different conditions of salinity were studied by means of morphological and morphometric analysis, and immunohistochemical identi®cation of cell proliferation (BrdU technique). In anterior (1±3) gills the epithelium thickness from crabs acclimatised to 12, 34 and 44 g}l ranged from 1±27 to 2±46 lm, with no signi®cant change during acclimatisation, thus denoting a respiratory function. Medial (4±5) gill epithelium was slightly thicker in extreme salinities, but these differences were not statistically signi®cant. In contrast, epithelial thickness of the posterior (6±8) gills increased signi®cantly up to 8±10 lm (dorsal zone of gill 8) both in hyper- and hyposaline media compared with seawater. The dark areas measured in gill 8 treated with AgNO$ revealed putative ion transporting tissue, especially at 12 and 44 g}l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.}l ranged from 1±27 to 2±46 lm, with no signi®cant change during acclimatisation, thus denoting a respiratory function. Medial (4±5) gill epithelium was slightly thicker in extreme salinities, but these differences were not statistically signi®cant. In contrast, epithelial thickness of the posterior (6±8) gills increased signi®cantly up to 8±10 lm (dorsal zone of gill 8) both in hyper- and hyposaline media compared with seawater. The dark areas measured in gill 8 treated with AgNO$ revealed putative ion transporting tissue, especially at 12 and 44 g}l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.±10 lm (dorsal zone of gill 8) both in hyper- and hyposaline media compared with seawater. The dark areas measured in gill 8 treated with AgNO$ revealed putative ion transporting tissue, especially at 12 and 44 g}l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.$ revealed putative ion transporting tissue, especially at 12 and 44 g}l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.}l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.}salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.