Cyclopia: an anatomic and histologic study of two specimens.

The craniofacial complex of two neonatal, human, cyclopic specimens was studied in detail. Both specimens exhibited a single ocular opening and one had a prominent probosics positioned in the midline directly superior to the ocular aperture. No external nasal development was noted in the other specimen. The most remarkable finding was the lack of development of all skeletal derivatives of the ethmoidal cartilage(cribriform plate, perpendicular plate, superior and middle nasal conchae, medial orbital walls, and nasal septal cartilage) in both specimens. Since these bones normally form the medial, lateral, and superior walls of the nasal passage, this cavity was also absent. The two posterior halves of the maxillae were directed superiorly, medially, and with the vomer merged in the midline as a thick mass of bone. As a result the right and left alveolar portions of the maxillae were joined superiorly in the midline. With the absence of the nasal cavity, the right and left medial pterygoid plates merged medially with the palatal and pyramidal processes of the palatine bone to obstruct the junction between the oropharynx and nasopharynx(choanal atresia). The role of the skeletal parts of the ethmoid during maxillofacial growth and development is discussed.