Transmission of proteins from mother to conceptus in the grey squirrel (Sciurus carolinensis).

Evidence has been obtained which suggests that maternal γ-globulin (γG) is readily transferred to the foetal circulation of the grey squirrel. This was shown in two animals by the transfer of human γ-globulin and in a third by transfer of anti- antibodies. Foetuses of all five pregnant squirrels studied, showed on analysis of their sera by immunoelectrophoresis a line indicative of γG but not of γM. Transfer of γG to exocoelomic, amniotic and yolk sac fluids, also occurred, but analysis of these fluids by immuno and polyacrylamide gel electrophoresis revealed a paucity of the high molecular weight α- and γ-macroglobulins, and lipoprotein. A pre-albumin component was present in relatively high proportion in all sera and fluids analysed and foetal sera were particularly rich in α-foetoprotein. Possible sites of transmission to the fluids and sera are discussed in relationship to the arrangement of the foetal membranes.