Fig. 3

Details of tentacle ultrastructure of Owenia borealis (TEM). A General view of epithelia and coelomic cavity of a tentacle. A cell of longitudinal muscle is shown in pink. B Different tentacle muscles: oral-aboral muscle is shown in violet, tentacle cross muscles are shown in orange. Peritoneal cells, which cover longitudinal muscles, are shown in dark green. A cell of the wall of blood vessel is shown in light green. Hemidesmosomes are indicated by double arrowheads. Abbreviations: aj – adherence junction; bb – basal body; bv – blood vessel; ci – cilium; ecm – extracellular matrix; gc – gland cell; mi – microvilli; n – nucleus; nb – neurite bundle; oam – oral-aboral muscle; pc – peritoneal cells; sa – secretory area of the gland cell; tcm – tentacle transverse muscles; tlm – tentacle longitudinal muscles