A unicellular endocrine gland in cestodes.

Unicellular glands are reported from the scolex and anterior neck region of Hymenolepis diminuta and H. nana. Despite positive staining reactions with the presumptive neurosecretory stains, paraldehyde-fuchsin and chrome-alum-hematoxylin, ultrastructurally these glands exhibit many non-neural characteristics. Glandular cell processes are frequently found in close proximity to muscular tissue, particularly in the suckers, suggesting a regulatory role in muscle modulation as a possible function. Two types of putative, neurosecretory cells are reported from the cephalic ganglia and the lateral nerve cords. Neurosecretory regulation of the unicellular endocrine glands is postulated based on the lack of direct innervation of the glands and the frequent close proximity of axons containing putative, neurosecretory granules.