Influence of reduced salinity on the histochemical fiber type composition of the claw closer muscle of two estuarine crab species, Cyrtograpsus angulatus and Neohelice granulata (Decapoda: Varunidae).

DÍAZ AO; LONGO MV

INTERNATIONAL JOURNAL OF MORPHOLOGY

Sociedad Chilena de Anatomía

Año: 2017 vol. 35 p. 533 - 540

0717-9367

The estuarine crustaceans are exposed to frequent and abrupt environmental salinity changes that involve adjustmentsat different levels in muscle tissue. The histochemical composition of fiber types of the claw closer muscle of Cyrtograpsus angulatusand Neohelice granulata (Dana, 1851) under hyper regulatory conditions was analyzed. Cryosections of the muscle were treated withmyosin-adenosine triphosphatase (m-ATPase), succinic dehydrogenase (SDH), periodic acid Schiff (PAS) and Sudan Black B. The meandiameters, the relative area and the proportion of each muscle fiber type were calculated. Types I and IV would belong to ?extreme?groups, whereas types II and III would be considered ?intermediate?. Type I fibers were large and exhibited a weak reaction to alltechniques; type IV fibers were small and reacted strongly to histochemical tests. Types II and III prevailed in C. angulatus whereas typeII predominated in N. granulata. Type IV fibers were absent in C. angulatus and scarce in N. granulata. The claw closer muscle of N.granulata and C. angulatus exhibited differential responses under reduced salinity at a histochemical level. Therefore, the existence ofdifferent adjustment mechanisms facing salinity stress is suggested