The effects of drugs on human foetal intestine.

The longitudinal muscle of human foetal intestine, of gestational age between eight and twenty-six weeks, has been studied in vitro using standard pharmacological methods. Muscarinic receptors and adrenoceptors have been identified in both the small and large intestine. The muscarinic receptors are similar to those of adult tissue whereas the adrenoceptor population of foetal intestine differs from that reported for adult tissue. In the foetal small intestine there is a predominance of beta receptors and the foetal colon contains alpha receptors which are involved in a contractile response to sympathomimetic amines. The responses to nicotine show that cholinergic and adrenergic fibres are present in the intestinal wall of the 12-week foetus.