Biology of Reproduction, Vol 14, 566-571, Copyright © 1976 by Society for the Study of Reproduction

Effect of Uterine Flushings on RNA Synthesis by ‘Implanting’ and ‘Delayed Implanting’ Mouse Blastocysts in vitro

¹ Department of Anatomy, School of Medicine, University of Oregon Health Sciences Center, Portland, Oregon 97201

Blastocysts were collected from the uteri of ‘normal’ and ‘delayed implanting’ mice and incubated with either Brinster’s medium containing ³H uridine, or the same medium mixed with material flushed from the uteri of ‘implanting’ or ‘delayed implanting’ animals. The rate of embryonic RNA synthesis was estimated from the incorporation of ³H uridine by the embryos in vitro. RNA synthesis by normal embryos incubated in Brinster’s medium was linear for at least 6 h. RNA synthesis by delayed implanting embryos in Brinster’s medium was initially low and increased to the level of normal embryos by the fourth hour in vitro. In contrast, RNA synthesis was low in both types of embryos incubated in medium containing uterine flushings; material from the uteri of ‘implanting’ animals was as effective an inhibitor of RNA synthesis as that from ‘delayed implanting’ animals. The apparent inhibitory activity is dialyzable and heat resistant. It is not known whether or not the inhibitory effect of uterine flushings on embryonic RNA synthesis found in vitro has any significance in vivo.

Note:
ACKNOWLEDGMENTS This work was carried out with the technical assistance of Ms. J. Hodson and supported by a research grant from the Public Health Service (HD 08496) and a Research Career Development award (HD 00020) from the Institute of Child Health and Human Development.