Assessment of histiotrophic nutrition using fluorescent probes.

Histiotrophic nutrition is a process whereby the rodent visceral yolk sac (VYS) internalizes exogenous macromolecules, degrades them, and sends the degradation products to the embryo for use in de novo macromolecular biosynthesis. This process is important for embryonic development during early gestation prior to the formation of the functional placenta. Quantification and visualization of histiotrophic nutrition can be accomplished using fluorescent tracer molecules such as fluorescein isothiocyanate-conjugated albumin (FITC-albumin) that can be visualized using fluorescent microscopy and quantified using fluorescent spectroscopy. The methods are simple and can provide complementary functional and structural information in studies of the effects of embryotoxicants on yolk sac function.