THE VAGINAL RESPONSE OF THE SPAYED EWE TO REPEATED INJECTIONS OF OESTRADIOL BENZOATE GIVEN ALONE OR PRECEDED BY PROGESTERONE

Abstract

SUMMARY: Seventy-two spayed Suffolk cross-bred ewes were used in a series of six trials, conducted at intervals of 16 days and designed to determine the quantitative vaginal response to oestradiol benzoate (ODB) when injected either alone or alternated with progesterone given at the rate of 10 mg/day for 12 days. The vaginal response to ODB when alternated with progesterone did not differ significantly from trial to trial. The vaginal response to ODB given alone showed a highly significant decline, with successive treatments, from a hypersensitive to a hyposensitive condition, clearly suggesting the development of a refractory state. It appears, therefore, that in addition to its role in maintaining a constant and highly sensitive state of psychic reactivity to ODB, progesterone is involved in the maintenance of a uniform vaginal sensitivity to this hormone.