Studies of the neurohaemal organ (sinus gland) of the portunid crab Portunus sanguinolentus (Herbst) (Brachyura). 1. Morphology and histology in relation to moulting.

The morphological and histological characters of the neurohaemal organ (sinus gland) of Portunus sanguinolentus are described in detail. The sinus gland lies on the dorsal surface of the optic ganglia, opposite the medulla interna. Histological techniques showed the presence of three tinctorially different secretory granules in the sinus gland. The predominant type of secretory material is basophilic and occurs as large granules, while two types of acidophilic material occur near the basement membrane. Cyclic changes in the relative amounts of acidophilic and basophilic material in correlation to moulting are also discussed. Allochthonous cells present in the sinus gland are identified.