Fig. 6
Sensory organs in Barentsia discreta and ultrastructure of nerve elements of the stalk in Barentsia discreta. a Abfrontal surface of a tentacle with bundles of cilia of sensory organs (SEM), (b) Cilia of the sensory organ of the tentacle (SEM), (c) Abfrontal surface of a tentacle tip showing cilia (cl) of unicellular sensory organs, (CLSM), (d) Serotonin-lir elements, whose location corresponds to the location of tentacle sensory organs, (CLSM), (e) Schematic structure of epidermal sensory cell, (f) Epidermal sensory cell at the base of tentacles, (g) Epidermal sensory cell of the apical part of the calyx, near the rectum, (h) Longitudinal section through the neurite bundle of the peduncle near the epidermis (ep), (i) Transverse section of the neurite bundle in the peduncle, (j) Oblique section through the neurite bundle of the muscular base near the cytons of muscle cells (ct). Abbreviations: abfabfrontal cell of tentacle; bl, basal lamina; cav, body cavity; cl, cilia of sensory cell; ct, cyton of muscle cell; cut, cuticle; cz, contractile zone of muscle cell; d, desmosome; ep, epidermal cell; int, interdigitations; mit, mitochondria; mv, microvilli; nb, neurite bundle; nf, nerve fiber; nuc, nucleus; scl, sensory cilia; se, serotonin-lir elements of the tentacle; t, tentacle