Protein composition of cerebrospinal fluid in the developing chick embryo.

Proteins from cerebrospinal fluid of chick embryos at 4-19 days of development were qualitative and quantitatively analyzed. The total protein concentration and the relative concentration of each protein fraction were calculated for each day. The main proteins found along development were immunoglobulin G, transferrin, alpha-fetoprotein, serum albumin, ovalbumin, prealbumin, and an unidentified component. alpha-Fetoprotein was found to be the major protein at 4-16 days, and serum albumin at 17-19 days of development. The unidentified fraction was present from 4 to 11 days; at day 5 it represented 28% of the total cerebrospinal fluid protein concentration.