SEM images of Sanguinicola spp. (A–D) and TEM images of the vitelline cells of Sanguinicola sp. 1 from pike (E–J). (A) Sanguinicola sp. 1 from pike, note the absence of visible lateral spines along the body. Scale bar = 200 μm. (B) Sanguinicola sp. 2 from ides, note the presence of lateral spines along the body surface. Scale bar = 100 μm. (C) Lateral spines of Sanguinicola sp. 2. Scale bar = 10 μm. (D) Spine of Sanguinicola sp. 1 localized laterally in the anterior third of the body. Scale bar = 1 μm. (E) Longitudinal section through part of the body, note vitelline cells at different stages of maturation mixed with other cell types. Scale bar = 50 μm. (F) Vitelline cells surrounded by tegumentary cells and muscle fibres. Scale bar = 5 μm. (G) Vitelline cells mixed with muscle and tegumental cells. Scale bar = 5 μm. (H) Vitelline cells surrounded by a muscle cell, note the neighbouring nerve cord and muscle fibres. Scale bar = 2 μm. (I) Mixed vitelline cells, muscle cells and muscle fibres. Scale bar = 5 μm. (J) Pseudopodia-like extensions of a vitelline cell directed towards a neighbouring vitelline cell and muscle fibres. Scale bar = 2 μm. Abbreviations: ab = anterior part of body, bs = body surface, cr = ciliary receptor, dc = distal cytoplasm of tegument, gc = globular cluster, l = lipid droplet, ls = lateral spine, mc = muscle cell, mf = muscle fibres, n = nucleus, nc = nerve cord, pb = posterior part of body, pe = pseudopodium-like extension, s = spine, tc = tegumentary cell, vc = vitelline cell.