ABNORMAL DIFFERENTIATION OF EMBRYONIC AVIAN BRAIN CENTERS ASSOCIATED WITH UNILATERAL ANOPHTHALMIA

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Abstract
Telencephalic, diencephalic, mesencephalic, and anterior rhombencephalic centers of the brain of a stage 38 chick embryo with unilateral olfactory, optic, and acoustic defects were studied to determine the effects of these sensory defects on the development of the central nervous system. A miniature telencephalic hemisphere with undifferentiated olfactory bulb is present on the side of the missing olfactory epithelium and olfactory nerve. On the side opposite the missing eye the nucleus ectomamillaris is missing, the stratum opticum of the optic tectum is exceedingly narrow, and the ventral lateral geniculate and nuclei externus and isthmoopticus are reduced in size. On the same side as the defect the pretectal centers and the nuclei isthmi parsprincipalis magnocellularis and parvocellularis are smaller. Reduction in number of motor neurons occurs in the centers supplying the extrinsic eye muscles of the abnormal side. Effects of retarded differentiation of acoustic sensory areas are reflected in the homolateral cochlear, vestibular, and inferior lateral cerebellar nuclei.