The outcome of unilateral occipital lobectomy in 12 foetal lambs in about the 100th day of gestation: a preliminary report

Effect of excision of occipital lobe tissue on about the 70th day of gestation on the growth and development of the sheep's brain

A unilateral occipital excision was performed on 14 fetal lambs at about the 70th day of gestation, and the brains were examined postnatally for gross morphological and histologic changes. Three operated brains revealed a posterior shift of the principal transverse sulcus in the ipsilateral hemisphere. This sulcus is remote from the area of excision, which was usually represented by a cystic cavity. Histologic examination showed that the dorsal lateral geniculate body was reduced in size in all but three of the operated brains. In two brains with the changed gyral pattern there was also a reduction in the size of the white fiber tracts of the frontal lobe. No evidence of neural regeneration was found in any of the brains. The implications of these findings from the point of view of possible neurosurgical intervention in the fetus are considered.