Fig. 4
Pachyzoon atlanticum. Histological details. a Section of frontal area showing elongated vestibular wall of retracted zooid. b Detail of diaphragmatic area showing elongated cone-shaped diaphragm and collar folds projecting into vestibulum. c Cross-section of diaphragm cone and radial collar. d Basal part of zooid. e Lateral kenozooid of colony with cystid appendages. f Detail of cystid appendages with thin or thicker cuticle. Abbreviations: bbw basal body wall, c collar, ca cardia, cy cystid appendage, es esophagus, fbw frontal body wall, kz kenozooid, l lophophore, o orifice, ph pharynx, ts tentacle sheath, v vestibulum, vco vestibular cone, vw vestibular wall