Brain(1), corpus allatum(2), and prothor-acic gland(3,4,5) of insects(6,7) have yielded respective active hormones on bioassay. Recently Kobayashi and co-workers(8) found cholesterol to be an active component in the brain of Bombyx. Schmialek(9) isolated farnesol and, with Wigglesworth(10), showed it to act in a manner similar to juvenile hormone (neotenin). Extracts of tissues from diverse biological sources have yielded positive bioassays for the presence of juvenile hormone (11). Since recent investigations (12,13) have demonstrated response of mammalian cells in vivo and in vitro to farnesol and ecdysone, whether ecdysone occurs in vertebrates (particularly human tissues) is also of interest.
Fortunately an excellent method of bioassay, the Calliphora test (14), is available for assessing the possible content of ecdysone in biological material. Fresh cadaveric tissue was obtained at autopsy and extracted by the same method yielding active material from Bombyx and Drosophila at appropriate stages of development(3,15). This was then tested for activity by injecting the posterior larval segment of ligated Calliphora in which the anterior segment alone pupated. The results are recorded in Table I.
No activity was found in any of the human tissues tested, although extraction of Bombyx chrysalises by the same process yielded active material. Large quantities of liver, brain, skeletal muscle, small intestine, and lung were used. In addition to the yields listed, quantities of testis, cardiac muscle, stomach, adrenal, pancreas, thyroid, and uterus of 500 g or less also failed to yield positive bioassays. Therefore, no evidence was obtained that ecdysone is contained in the human tissues tested or the amount is so small that the sensitive methods used failed to detect it.
The technical assistance of Mr. Lloyd Paul, Miss Gale Christensen, and Mr. Nick Wiser is acknowledged with appreciation.
