[New aspects of the ontogenetic development of the human colon]. 
The parts of the fetal colon--later retroperitoneally located (ascending and descending colon)--were examined in 31 human fetuses in order to determine their ontogenetic formation, position, and dorsal attachment.  The present data cast doubt upon so-called "descending of the caecum" described in current textbooks of embryology.  Considering the literature available a new concept of the formation of the right colon flexure and the ascending colon is presented.