Use of the periodic acid schiff stain to grade retarded fetal renal development in mice

In an earlier study, maternal mice were given by gavage 60–120 mg/kg 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on days 6—14 of pregnancy and sacrificed on day 17. The Gomori stain revealed diminished alkaline phosphatase in the renal proximal tubules of fetuses exposed to 2,4,5-T during gestation indicating retarded renal functional and, probably, morphological development. Spare sections of the fetal kidneys from the earlier study were stained by the periodic acid-Schiff (PAS) procedure. This revealed, in exposed fetuses, a reduction of renal tubules with PAS-positive material in the brush borders comparable in incidence and distribution to those with alkaline phosphatase in the earlier study. These findings indicate that PAS can replace the Gomori stain as a screening procedure when retarded fetal renal development by a toxic agent is suspected. Unlike alkaline phosphatase, the PAS procedure is effective even after prolonged fixation in Bouin's solution which is commonly used in fetal studies.