Early trabeculation and closure of the interventricular foramen in staged human embryos

Abstract

Internal differentiation of the ventricles was studied in staged serially sectioned human embryos of developmental stages 13-19 (postovulatory days 32-46). At stage 13 the trabeculation of both ventricles was advanced and the muscular part of the interventricular septum well marked. Dorsal and ventral endocardial cushions were fused and the atrioventricular canal was divided into two parts. In embryos at stage 18 the membranous interventricular septum was developing and the interventricular foramen was obliterated. At stage 19 the membranous part of the interventricular septum was becoming more cellular in structure.
(Folia Morphol 2008; 67: 13–18)