EFFECT OF A SINGLE DOSE OF TESTOSTERONE PROPIONATE ON VAGINAL OPENING IN THE RAT

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Abstract
The action of a single dose of testosterone propionate on the vaginal opening in 167 Wistar Rats injected at different ages, was studied. The vagina in animals injected at the day of birth failed to open. The observation period lasted for 18 months. Vaginal opening in animals injected at 24 or 48 hours was characterized by a very small orifice which appeared between 9 and 13 days of age. When adult, these animals had a smaller vaginal orifice. The animals injected 3 days after birth behaved as if they belonged to two different groups: 50% showed precocious and abnormal vaginal opening similar to the anterior group, and 50% showed a precocious and clear opening of their vagina. In animals injected when 4 or 5 days old the vagina opened clearly and precociously (between 9 and 13 days), and the animals injected at the 10th day showed a precocious vaginal opening similar to the previous group between 16 and 19 days of age. To explain the opposite effect of the testosterone propionate injected at the day of birth or at the 4th day after birth, the authors suggest that the enzymatic systems that transform testosterone into substances with estrogenic properties are not present in newly born animals. In subsequent days these systems would maturate and enough substances would be produced.