Dynamics of antibody transfer from mother to fetus through the yolk-sac cells in the rat.

In rodents, maternal immunoglobulins are transported intact by the yolk-sac visceral epithelium from mother to fetus. The main purpose of the present paper is to study the dynamics of the uptake and transport of immunoglobulins by the rat yolk-sac using a new experimental design. The results show the rapid binding of IgG to the cell membrane microvilli since only 30 sec were sufficient for this attachment to occur. The endocytic process also appears to be very fast as localization of IgG in clusters, pits and microvesicles were observed after 5 min of contact between the yolk-sac and the IgG solution. Moreover, the antibodies were detected in the intracellular spaces within 15 min of incubation.