PEROXISOMES AND PEROXISOMAL ENZYMES IN THE HUMAN FETAL SMALL-INTESTINE

The appearance and development of peroxisomes and the expression of th eir enzymes in the human fetal intestine have been investigated betwee n 11 and 22 weeks of gestation. In the youngest samples (11-16 weeks o f age), cytochemistry at the ultrastructural level revealed the presen ce of rare, mostly circular peroxisomes. From 16 weeks of gestation on wards, an increase was noted in the number of peroxisomes. Two peroxis omal types were distinguished: round to oval forms and elongated and/o r tailed organelles. Biochemical assays revealed that total and specif ic intestinal catalase activities increased gradually between 11 and 2 0 weeks of gestation. The activity of fatty acyl-CoA oxidase, the firs t enzyme of the peroxisomal beta-oxidation system, was detectable as e arly as 11 weeks of gestation. Thereafter, total and specific activiti es of the enzyme increased steadily. Activities of other peroxisomal o xidases (D-amino acid oxidase, L-alpha-hydroxyacid oxidase) appeared m ore slowly in the fetal intestine during the period studied. This inve stigation establishes the presence and the morphological changes that occur in intestinal peroxisomes during human fetal development as well as the developmental patterns of associated enzymes.