Biochemical differentiation of gestational compartments in the midgestational fetal rabbit.

OBJECTIVE

The fetal rabbit at midgestation is increasingly being used as a model in fetal diagnosis and therapy. In this study, we aimed to establish a reliable method for identification of the origin of sampled extra-embryonic fluids based on selected biochemical components.

METHODS

In 6 pregnant does at 22 days of gestation, 18 gestational sacs were sampled for amniotic, allantoic and exocoelomic fluid. These fluids, as well as matching maternal and fetal blood samples, were assayed for levels of sodium, potassium, chloride, bicarbonate, total protein, alkaline phosphatase, gamma-glutamyl transferase and progesterone.

RESULTS

Levels of sodium and potassium were, respectively, lower and higher in the allantoic fluid when compared to other extra-embryonic spaces. Amniotic fluid had a significantly lower total protein content and higher level of alkaline phosphatase when compared to the exocoelomic fluid. Significant levels of progesterone could only be detected in maternal blood.

CONCLUSIONS

In the midgestational rabbit, a combined assay of potassium, alkaline phosphatase and progesterone can determine the gestational cavity of origin of the sampled fluid. The obtained gradients for these markers suggest compartment-specific production and/or inter-cavity transfer mechanisms.