The epipharynx in normo- and pathogenesis.

We studied the development of the epipharynx in normal human ontogeny comparing findings in fetuses with severe CNS malformations with those of normal fetuses of a comparable stage of development. Normally, the epipharynx forms a tube and bends at a right angle, whereas, in the fetuses with CNS malformations, the epipharynx develops as a balloon-like form of slightly triangular shape. In hydrocephaly, it formed a narrow tube that was nearly vertical. We concluded that the early formation of the epipharynx is influenced by the separation of the notochord and the formation of the basicranium, by ascendant processes during vertebrogenesis, and by the neotenic development of the maxillomandibular complex.