EPITHELIAL CYTOLOGY AND FUNCTION IN THE DIGESTIVE GLAND OF THENUS-ORIENTALIS (DECAPODA, SCYLLARIDAE)

The morphology and epithelial cytology of the digestive gland of the s lipper lobster Thenus orientalis is described. The primary ducts posse ss extensive musculature which indicate that they may move fluid into and out of the glands. Immunohistochemical localization of trypsin dem onstrated that it is synthesized and secreted solely by the F-cells in the digestive gland. Trypsin is absent from tissue in the oral region , proventriculus, and hindgut, but is present in digestive fluid throu ghout the alimentary tract, indicating that it has a role in extracell ular digestion. Substantial accumulations of lipid in the cytoplasm of R-cells indicate a role in the absorption and storage of digestion pr oducts. Residual bodies in the apical cytoplasm are consistent with me tal-storing granular inclusions and supranuclear vacuoles in the R-cel ls of other decapods. Based on the presence of an apical complex of pi nocytotic vesicles and subapical vacuoles, an absorptive role for B-ce lls is evident. The presence of trypsin in the central vacuole is cons istent with a digestive role, although our results cannot distinguish whether the enzyme is endogenous (lysosomal versus digestive) or was a bsorbed from the tubule lumen for excretion.