Effects of trypan blue and Niagara blue 2 B on the in vitro absorption of ions by the rat visceral yolk sac

Abstract

ABSTRACT Prior to 1927, when Brunschwig proposed that the rat visceral yolk sac is functionally a placenta, it was customary to consider the chorio-allantoic placenta as the primary organ for bringing nourishment to and taking waste from the developing embryo and growing fetus. Eight years later, Everett (1935) predicted that the visceral yolk sac is functionally at least as important as the chorio-allantoic placenta, while Noer & Mossman (1947) suggested that the yolk sac functions differently from the placenta and is therefore complementary in its role. More recently, Halliday (1955) indicated that the proximal yolk sac of the rat is capable of absorbing antibodies by day 17 of gestation. This was confirmed by Brambell & Halliday (1956), who were able to demonstrate that the vitelline epithelium and its underlying vascular system are partly responsible for antibodies penetrating into the embryo. Padykula, Deren & Wilson (1966) noted that the rat yolk sac has the ability to absorb vitamin B12 and that this ability is stimulated by the presence of intrinsic factor. The yolk sac has also been shown to be capable of actively transporting certain amino acids (Deren, Padykula & Wilson, 1966) and is able to accumulate ferritin by means of pinocytosis (Lambson, 1966).