OBSERVATIONS ON THE PROPERTIES AND BIO-ASSAY OF ESTRIN

¹ Department of Physiology, Edinburgh University

1. The effect of the mouse or rat unit of strin as tested by the vaginal smear is not always the same, and at present cannot be regarded as quantitative except in the sense of an approximation. The unit-concept is not therefore to be regarded as a fixed one.

2. Notwithstanding this, it can be affirmed that, within limits, there is no appreciable difference between the quantity required to produce a reaction in the mouse from that required for the rat. This also applies to the Nissl test.

3. The technique of the vaginal smear test is described, and emphasis is laid upon the necessity for attention to general hygiene, to the temperature of the environment, and to various minutiæ.

4. Neither the weight of the animal nor the effect of previous injections produce an appreciable effect on the vaginal reaction to strin.

5. Objections are made to the practice of partition of the dose. It is advocated that for vaginal tests and for the Nissl test single doses be administered. This is, however, not possible for the growth test.

6. It is suggested that a practicable end-point for the smear reaction is furnished by a cell-picture showing an almost complete disappearance of leucocytes, with at least half the epithelial cells showing cornification.

7. Differences of the mucus content of the smear and two types of mucus are described.

8. It is shown that rats may show a different response to identical doses of strin at different times.

9. Very early oöphorectomy diminishes the sensitivity to strin.

10. The greater potency of subcutaneous as compared with intra-peritoneal injection is confirmed.

11. The growth test is described and is advocated as having a distinct place in the bio-assay of strin.

12. The Nissl test is described and is suggested as the most suitable for accurate investigation.