part of part of immediately preceded by immediately preceded by occurrent stage 18 late organogenesis stage very late organogenesis stage The embryo displays prominent right and left anterior coelomic pouches, and the posterior enterocoel has enlarged. Pronounced cardiac and developing pyloric constrictions (separating respectively the foregut and midgut, and the midgut and hindgut) are formed, and the gut is thus visibly tripartite, with the posterior enterocoel projecting from the developing stomach (former midgut). The wall of the left anterior coelom is distended at both its anterior and posterior margins, where strands of cells extend to the ectoderm. Muscle bands surrounding the esophagus are apparent. Ridges of thickened ectoderm mark the positions of the future ciliary bands. ecao_developmental_stage