BIOLOGICAL CHARACTERISTICS OF PITUITARY AN PLACENTAL HORMONES

The biological characteristics of gonadotrophin and prolactin were studied by their effects upon the ovaries and the intact and damaged uterine horns of 3-month-old mice which had been hypophysectomized on the first day of dioestrus. The method, developed primarily for measuring luteotrophin by the formation of deciduomata in the damaged uterine horn, was called the deciduoma assay but it can also differentiate the activities of fsh and lh. The decidual reaction in the damaged uterine horn appears to be a suitable endpoint for measuring ovarian progestagen released by the activity of luteotrophin, human luteinizing hormone or placental hormones. These preparations are deciduotrophic but they are not all classified as luteotrophins. The term `luteotrophin' is reserved for preparations which cause hypertrophy of luteal cells accompanied by hyperaemia of the corpora lutea and which are deficient in other gonadotrophic activities. Only preparations of ovine prolactin and luteotrophin in human and bovine growth hormones and bovine thyrotrophin are therefore included in this group. The deciduoma method is possibly invalid for the assay of mixtures containing relatively large amounts of fsh because the growth of follicles results in the elimination of corpora lutea. However, the method can be used to demonstrate biological differences between similar hormones and it may be of value in studies on the purification of hormones.