Carbonic anhydrase activity during development of the choroid plexus in the human fetus

Carbonic anhydrase is one of the key enzymes responsible for the secretion of cerebrospinal fluid. This secretion increases dramatically during postnatal life in mammals. Nothing is known that can account for this regulation in the neonatal choroid plexus. However, the expression of carbonic anhydrase is developmentally regulated in several cells, such as erythrocytes and striated muscle fibers. The aim of our study was to assess the presence of carbonic anhydrase in epithelial cells of the choroid plexus during human development. We performed both histochemical and immunohistochemical detections of the enzyme on choroid plexuses between 9 and 34 weeks of gestation. We found that both carbonic anhydrase activity and the isozyme II were present as early as the 9th week of gestation. expression of carbonic anhydrase is thus a very early event during plexus differentiation, and this enzymatic system could account for the secretion of cerebrospinal fluid during fetal life.