Distribution of an adenohypophysial constituent in the body. II. Quantitative tissue distribution in the rat.

A peptide with a molecular weight of about 5000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm-releasing substance is not part of any known gonadotropic hormone. The tissue distribution of this substance has been investigated. The iodinated substance has been injected into rats and the radioactivity content of the different tissues has been determined. Iodinated rat albumin has been injected into other rats, to determine the content of blood in the different tissues. A formula has been derived to obtain a figure for real accumulation, using the radioacitivity content of the blood and of the tissues after injection of the sperm-releasing substance and albumin, respectively. The sperm-releasing substance is incorporated into the adenohypophysis, neurohypophysis, liver, kidney, lung, ovary, uterus and some male sexual organs. The causes for this distribution are discussed.