Cyclopia

CYCLOPIA (from the Greek kyklops - round-eyed cyclops), or cyclocephaly, a developmental anomaly of the face and eyes leading to monophthalmia and thus some resemblance of the fetus's face to the face of the mythical cyclops. Morphologically, the absence of the olfactory and nasal regions of the brain (arynencephaly) and underdevelopment of the ethmoid bone are observed; the orbit is common to both adjacent eyes (synophthalmia) or there is only one eye. The nose is absent and in its place a peculiar cutaneous or cutaneous-cartilaginous proboscis is noted, sometimes compared to the penis (endocephaly). Cyclopia may be associated with various facial anomalies, synotia, agnathia, general underdevelopment of the cerebral hemispheres, sometimes represented by only a cerebral vesicle. The optic nerves are often completely absent or fused into a single nerve trunk. Signs of underdevelopment are observed on the part of the visual tubercles, striated bodies, and associative pathways. Cyclopes are nonviable and usually die in the first weeks of life. Cyclopic forms have been obtained experimentally in fish and salamanders by changing the chemical composition of the water in which the fertilized eggs were located. It is highly probable that the initial stage of cyclopia development belongs to the earliest stages of embryo development, possibly even before the gastrulation period.