Strontium Retention in Mouse Foetuses at Different Intervals after Contamination of the Dam

Abstract

Pregnant CBA mice were intravenously contaminated with radiostrontium (⁸⁵Sr) on either the 14th, 16th or 18th day post coitum. The radiostrontium content in the foetuses and corresponding placentas as well as that in the femurs of the mothers was measured separately and individually on the 19th day post coitum, i.e. after intervals of 5, 3 and 1 day, respectively. The retained amount of strontium in the foetuses successively increased by the time of contamination, i.e. the later during pregnancy the contamination occurred. Expressed as per cent of the injected amount of ⁸⁵Sr, the figures ranged from 4.6 per cent in foetuses contaminated on the 18th day to 0.7 per cent for those contaminated already on the 14th day after coitus, with a significantly negative correlation between time and retained amount of radiostrontium. The amount of strontium in the femurs of the mothers was reduced within the same intervals, due partly to decalcification of the skeleton of the mother during the latest part of the pregnancy.