Absorption of Crystalline Estrogen from Paraffin Nodules in the Rat. ∗

Abstract

Summary

An effective and simple method of insuring slow continuous absorption of estrogen in the rat is the incorporation of the crystalline hormone in paraffin (melting point 48°C), which after subcutaneous, intramuscular, or intraperitoneal injection in a liquid state, solidifies locally. As indicated by vaginal smear, the average time required for complete absorption and utilization of 5.0 mg estradiol dipropionate contained in 0.1 cc paraffin, introduced into animals 3 to 5 weeks of age, is 151 ± 5.9 days. In males the position and activity of the testes are comparable indicators of the utilization of the injected estrogenic hormone.