The Choroid-Plexus In Fetal Sheep During Development With Special Reference To Intracellular Plasma-Proteins

The developmental stages of the telencephalic, diencephalic and myelencephalic choroid plexuses and the morphology of the choroid plexus epithelial cells in the fetal sheep during development are briefly described. The individual choroid plexuses at different developmental stages were investigated by the indirect immumoperoxidase technique. The number and distribution of albumin-, alpha-fetoprotein-, fetuin-, transferrin-, and alpha 1 -antitrypsin-containing cells were recorded. Early in gestation 30–50% of the epithelial cells in the telencephalic choroid plexus were positive for albumin, alpha-fetoprotein and fetuin, and this proportion declined later in gestation to a few percent. In contrast, during the entire gestational period investigated, less than 10% of the epithelial cells in the diencephalic and myelencephalic choroid plexuses showed a positive staining reaction for the various proteins. The cells containing plasma proteins did not belong to a single type. No positive staining reaction for transferrin and alpha 1 -antitrypsin was found in the choroidal epithelium in any of the individual plexuses. The results are compared to the staining pattern in human fetal choroid plexus. Furthermore, the results are discussed in relation to the concentration of the proteins in CSF and their transfer from blood to CSF.