THE NOTOCHORD AS AN ABNORMAL ORGANIZER IN PRODUCTION OF CONGENITAL INTESTINAL DEFECT

Fifty-eight cases of congenital defects in hind gut were studied for associated lumbosacral vertebral anomalies. These were found in 16 per cent of anal and 42 per cent of rectal ageneses, respectively.

The vertebral deficiencies are of types known to follow abnormal development of the notochord in cervical regions. This inconspicuous thread, besides being the first semblance of a human axial skeleton, is an organizer. Where it overdevelops, it prevents the fusion of chondrification centers anteriorly. Severe inhibition of contiguous endodermal fore and hind gut is likely to occur. It is as though the dominant connective tissue inductive capacity of the notochord produces inhibition of endoderm segments when these lie in proximity.

The disturbances in sequential organogenesis when the notochord is exposed in cervical and sacral regions are reviewed and counterparts identified. Normal development of the intestine is therefore partly dependent upon exclusion from influences of organizers for unrelated structures, which are forming at an early age in adjacent sites.

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