Transfer of Proteins from the Yolk to the Chick Embryo

Transport across endodermal cells of the chick yolk sac during early stages of development

“…It has been demonstrated that some serum proteins and antibodies are endocytosed by mammalian endodermal cells, but that some of these proteins escape degradation and are transmitted unaltered to the embryonic circulation (Schechtman, 1956;Wild, 1970;Wild et al, 1972;Moxon et al, 1976;King, 1977). Such a pathway in the chick endodermal cells might account for the reported transmission, intact, of serum proteins of high molecular weight (Schechtman and Knight, 1955;Brambell, 1970;Wild, 1970;Wild et al, 19721, and antibodies (Brierly and Hemmings, 1956;Wild et al, 1972), from the yolk mass to the embryonic circulation.…”

The Roles of Amino Acids in Animal Embryogenesis

“…But Walter & Mahler (1958), using radioactively labelled protein, peptide and amino acid separately, added to either yolk or albumen, found that peptides and amino acids were taken up equally from albumen and yolk for the first 9 days, although whole protein was absorbed only from the yolk during this time. Their method did not exclude the possibility that the protein was first broken down in the yolk: indeed, although Schechtman & Knight (1955) and Brierley & Hemmings (1956) have shown that some, serologically recognizable, can pass intact from yolk to the chick embryo, we still do not know to what extent this happens in normal development. It would require some special mechanism such as pinocytosis, and it is not known yet whether this occurs in the cells of chick embryos, although Bellairs (1962) has described outgrowths seen in electron micrographs of extra-embryonic endoderm that might possibly be concerned in pinocytosis.…”

Protein nutrition in growth regulation during early development

“…Bovine "^globulin and serum albumin injected into eggs can be detected in the embryo and embryo serum after eight days of incubation (Schechtman and Knight, 1955). That the passage of proteins is a selective process was suggested by detecting the presence of circulating antibodies in hatched chicks when fowl sera was injected into the yolk-Bac at six to eight days of incubation but not when sera from the rabbit, cow, or horse were handled in a similar manner (Brierly and Hemmings, 1956).…”