Everett, John W.
Everett had his early education in the public schools of Big Rapids and at Olivet College, Olivet, Michigan. This was followed by postgraduate study at Yale University from 1928–1932. The title of his dissertation was “Functions of the Placental Membranes of Albino Rat as Indicated by Their Reaction to Vital Dyes.” Everett moved to the Department of Anatomy, Duke University School of Medicine, Durham, North Carolina as Instructor in Anatomy. The appointment as Professor of Anatomy came in 1950. “A modest man, John Everett is no empire builder and has much preferred to work with just one or two collaborators. Nevertheless, his scientific interests are wide. Everett is famed for the meticulous design and execution of experiments, using the simplest and most reliable techniques available, and for careful and cautious evaluation of the findings.” Everett discovered a positive-feedback influence of progesterone, the induction of ovulation in persistently estrous rats. He was able to manipulate the length of the estrous cycle by the appropriate differentially timed injection of either estrogen or progesterone in normally cycling rats. Everett developed the concept of a proestrous “critical period.” Several hypotheses were proposed with respect to mechanisms whereby the sex steroids may act to induce ovulation in the rat. The first is that there is a surge of luteinizing hormone-releasing hormone (LH-RH) every afternoon and that whether the pituitary responds depends on the rise of estrogen. The second proposal holds that activity from the rostral hypothalamus impinges on the medial basal tuber at a regular time each day, but that the occurrence of an LH-RH surge is contingent upon steroid actions in the tuberal nuclei and median eminence. The third hypothesis is that there is (an intrinsic?) 24-h rhythmicity in the rostral hypothalamus, but that it becomes active only through some local actions of the steroids. In his Dale Medal Lecture in 1977, Everett added that a modification of this last hypothesis would state that activity in the rostral, cyclic apparatus is not only dependent upon local action of steroids, but is subject to modulation by stimulatory and inhibitory input from other parts of the brain. That would place the “clock” in the mid-brain or somewhere else downstream. He ends with the question: “Are we chasing a will o’ the wisp? Is there really a localized clock?”
References and Other Sources
- Everett JW (1975) Contributions to the substructure of neuroendocrinology. In: Meites J, Donovan BT, McCann SM (eds) Pioneers in neuroendocrinology, vol 1. Plenum, New York, pp 96–109.Google Scholar