Peroxisomes and peroxisomal enzymes in the human fetal small intestine.

Abstract

The appearance and development of peroxisomes and the expression of their enzymes in the human fetal intestine have been investigated between 11 and 22 weeks of gestation. In the youngest samples (11-16 weeks of age), cytochemistry at the ultrastructural level revealed the presence of rare, mostly circular peroxisomes. From 16 weeks of gestation onwards, an increase was noted in the number of peroxisomes. Two peroxisomal types were distinguished: round to oval forms and elongated and/or tailed organelles. Biochemical assays revealed that total and specific intestinal catalase activities increased gradually between 11 and 20 weeks of gestation. The activity of fatty acylCoA oxidase, the first enzyme of the peroxisomal beta-oxidation system, was detectable as early as 11 weeks of gestation. Thereafter, total and specific activities of the enzyme increased steadily. Activities of other peroxisomal oxidases (D-amino acid oxidase, L-alpha-hydroxyacid oxidase) appeared more slowly in the fetal intestine during the period studied. This investigation 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.