Histological observations of septum from type I intestinal atresia and residual vacuoles during recanalization in fetal period

Objective To explore the morphology of septum in type I intestinal atresia and examine residual vacuoles during recanalization in fetal period. Methods A total of 15 septum collected from departments of pediatric surgery at three hospitals.After serial tissue sectioning, hematoxylin-eosin (HE) and Masson stains were performed for histological observations of residual vacuoles during recanalization in fetal period. Results Macroscopic observations indicated that septum with central hole was noted in 3 samples and the remainders belonged to complete septum.Mucous layers covered both sides of all septums and continued at central septum.Submucosal and longitudinal smooth muscles could be seen between both sides of mucous layer.However, circular smooth muscle and serosa were absent.Among all samples, residual vacuoles during recanalization in fetal period could be occasionally seen in 2 septum tissue samples among longitudinal smooth muscle.Residual vacuoles had complete cystic wall and was encircled by fibrosis.And red necrotic tissue was found in outer surface of residual vacuoles. Conclusions Mucous layers cover both sides of septums and continue at central septum in type I intestinal atresia.It suggests that recanalization in fetal period occurs in differential parts of fetal intestine and this biological process compromises proximal and distal continuity of mucous layer, submucosa and muscular layers.There is never one-way direction.Microscopic residual vacuoles further provide biological evidence for recanalization theory in fetal period. Key words: Intestine; Atresia; Septum; Vacuoles; Histology observation