Figure 2. Mesomyzostoma katoi Okada, 1933 in Four new species of Mesomyzostoma (Myzostomida: Annelida)

Figure 2. Mesomyzostoma katoi Okada, 1933. (A) One-micrometre semithin section through body showing the single ventral nerve cord, a ventrolateral parapodium, central gut lumen, lateral gut diverticula spermatogonia/spermatids, spermatocysts and mature sperm in the vas deferens (SIO-BIC A4071). (B) Enlarged region of A showing the parapodium with its emergent hook as well as male reproductive cells. (C) Planktonic larval stage fixed in osmium tetroxide; the larva has two bundles of chaetae and an anterior ciliary ring (not visible). (D) Micrograph of a parapodium digested in bleach showing the parapodial hook apparatus. Abbreviations: ch, chaetae; dt, gut diverticulum; e, epidermis; m, muscle; p, parapodium; g, gut; h, hook; sc, spermatocycts; st, spermatogonia/spermatids; vd, vas deferens; vnc, ventral nerve cord.