Fig. 4

Histological cross sections of anterior segments in Typosyllis antoni (two different specimens, b-d respectively e-g), Azan staining. a Schematic representation of T. antoni with the locations of each cross section. b Pharynx. c Anterior end of proventricle and schematic representation of the upper left quarter of the proventricle (down right, with colors according to label colors). d Proventricle. e Ventricle. f Caeca region. g Midgut. Abbreviations: ca, caeca; cu, pharyngeal cuticle; dbv, dorsal blood vessel; dci, dorsal cirrus; dlm, dorsal longitudinal musculature; ec, gut epithelium of the caeca region; eca, caeca epithelium; ecm, extracellular matrix; eg, midgut epithelium; ep, epithelium of the proventricle; eph, pharyngeal epithelium; ev, epithelium of the ventricle; mc, gut musculature of the caeca region; mca, musculature of caeca; mg, midgut musculature; mph, pharyngeal musculature; nc, neurochaetae; nu, nucleus; sa, sarcomere; sp, sarcoplasm; vlm, ventral longitudinal musculature; vn, ventral nerve cord; zd, z-disc