THE EVALUATION OF GONADOTROPIC HORMONE PREPARATIONS ON THE BASIS OF THE RAT-MOUSE RATIO ASSAY

¹ The Department of Anatomy, University of Missouri

A group of gonad-stimulating preparations including extracts of pituitary glands, pregnancy urine, and pregnant mare serum were assayed simultaneously on infantile rats and mice. Observations were made upon vaginal openings and smears, ovarian weights, the degree of follicle stimulation, and the occurrence of corpora lutea. On the basis of these assays a ratio between the rat and mouse units for each preparation has been observed. A total of 227 rats and 211 mice were employed in this study.

For the pregnancy urine preparation the rat-mouse ratio was found to be about 5:1 in favor of the mouse, i.e., the mouse unit is five times as large as the rat unit.

In the case of the pituitary extract the ratio was about 3:1 in favor of the rat.

For the pregnant mare serum preparation the ratio was approximately 2:1 in favor of the mouse.

It would appear probable that the variations in the rat-mouse ratio for the several preparations has its explanation in different proportions of the follicle-stimulating and luteinizing factors present in them acting in conjunction with the follicle-stimulating hormone produced by the pituitaries of the test animals. The possibility of different states of follicular maturity existing in the ovaries of rats and mice of the test age is also considered.

The rat-mouse assay ratio offers a method of differentiating between anterior pituitary and anterior pituitary-like gonadotropic hormone complexes.