[Mucin histochemistry of the digestive tract in the human fetus]

Mucin secretion was studied in the gastric, intestinal, left colic and/or rectal mucosa of 42 human fetuses ranging in age from 10 to 41 weeks of gestation (menstrual age). Several histochemical techniques were used at different pH to demonstrate neutral mucins, sialomucins and sulphomucins (Periodic Acid Shiff (PAS) with and without amylase, Alcian Blue (BA) pH 2.5, pH 1 with and without hyaluronidase, BA/PAS pH 2.5 and High Iron Diamine (HID)/BA). The gastric mucosa showed mixed neutral/acid secretions during the second term. The neutral mucins increased during the 3rd term when acid mucins fell and represented only 20 percent of the secretions by the end of gestation, as during the neonatal period. These mixed secretions closely reassembled the intestinal metaplasia described in inflammatory or tumoral lesions of the stomach. The intestinal mucosa secreted mucins as early as 10 weeks before the gastric and rectal mucosa. There were neutral and acid mucins, but unlike in adults, the sulphomucins were secreted by the goblet cells of the villous and crypt epithelia. The secretions of the rectal mucosa were acid and the sulphomucins increased in quantity from 14 to 26 weeks of gestation. The HID positive sulphomucins diffused into the meconium, and probably modified the physical and chemical properties of meconium and influenced anal continence.