SENSORY INNERVATION OF THE LOPHOPHORE AND ORAL-REGION IN CHEILOSTOMA-BRYOZOA

The sensory capacities of a polypide are investigated in different spe cies by the methylene blue staining method for nerves and by a complem entary ultrastructural study. Sporadic ciliate epithelial cells along the underlying aboral nerve of the tentacles are described and compare d to similar cells in a ctenostomate. A potential sensory cell is obse rved at the tip of the tentacles. Morphological and ultrastructural ob servations reveal two rows of sensory cells around the base of the lop hophore, that nerve fibers link to the cerebral and peripharyngeal gan glions. The club shaped cells of the upper row are found at the base o f every tentacle together with a subjacent support cell at the junctio n of the tentacle and tentacle sheath. They are similar to potential s train-receptors which were previously described in the external wall b y the cytoskeleton and microvilli of their swollen ending. A pair of s ensory cells linked to the lateral visceral nerves is observed in the sub-oral region of the pharynx. Other sensory cells were not found in the following regions of the digestive tract.