Über die Beziehungen Zwischen Hypophysenvorderlappen und Keimdrüsen

The hypothalamus and sexual maturation in the rat

“…An important difference between infantile and adult individuals, which could account for the relative quiescence of the infantile gonad, would appear to be a higher sensitivity of the infantile hypothalamus to gonadal hormone. Hohlweg & Dohrn (1931) found that in infantile rats the pituitary changes after gonadectomy could be prevented by gonadal hormone in doses approximately one-hundredth of that required in the adult. A fundamental change, then, in the advance toward sexual maturity would seem to be a reduction in the sensitivity of the hypothalamus toward gonadal hormone.…”

“…There is no doubt that the infantile pituitary gland secretes gonadotrophic hormone, for hypophysectomy of infantile rats results in an arrest of gonadal development both in females (Walker, Simpson, Asling & Evans, 1950) and in males (Walker, Asling, Simpson, Li & Evans, 1952). The infantile gonad likewise produces sex hormones: prepubertal castration is followed by early regression of male accessories in the rat (Clark, 1935), by increased excretion of gonadotrophin in a child (Hamilton, 1948), by an increase in pituitary content of gonadotrophin (Heilbaum & Greep, 1940), by an increase in pituitary weight (van Rees & Paesi, 1955) and by the development of 'castration-cells' in the pituitary gland (Dohrn & Hohlweg, 1931). Also, if one of a pair of infantile rats united in parabiosis is castrated, then the partner will display precocious puberty (Kallas, 1929(Kallas, , 1930.…”

“…Also, if one of a pair of infantile rats united in parabiosis is castrated, then the partner will display precocious puberty (Kallas, 1929(Kallas, , 1930. Such changes following gonadectomy in the infantile individual are believed to be due to a lack of gonadal hormone in the blood and, indeed, it has been demonstrated that castration changes in the pituitary gland of infants can be prevented or inhibited by exogenous gonadal hormone (Dohrn & Hohlweg, 1931), whereas precocious puberty in an otherwise intact parabiotic rat can be prevented by the administration of low doses of gonadal hormone to the castrated partner (Byrnes & Meyer, 1951). A temporary fall in the blood level of gonadal hormone, with a consequent increase in gonadotrophin secretion, is believed to be the cause ofthe precocious puberty which is observed after auto-transplantation of infantile ovaries (Pfeiffer, 1936;Greep & Jones, 1950;Almqvist & Jacobsohn, 1956; der Werff ten Bosch, unpublished).…”

Maturation of the Hypothalamic-Pituitary Axis Regulating Gonadotropin Secretion in the Primate

“…Such a proposal forms the basis of the "Gonadostat" hypothesis, first proposed in 1932. 44 Through several refinements and data generated largely in several animal models, this hypothesis proposed that the young (juvenile) subject is exquisitely sensitive to the negative feedback effect of gonadal steroids. 45 " 48 According to this hypothesis, the pubertal rise in gonadotropin secretion occurs when the sensitivity of the young animal to steroid negative feedback begins to decrease to levels typical of adults of the same species.…”

Puberty in Mice and Rats

“…In the early 1970s, Raisman and Field showed that the hypothalamic preoptic area was indeed sexually dimorphic, with a greater number of dendritic spines in females than in males, an effect dependent on gonadal steroid action in the early postnatal period. Even more importantly, how was it that minute amounts of ovarian or testicular hormones could prevent the formation of these cells 74,75 or the accompanying effect on puberty in immature animals? For this monumental work, they shared the Nobel Prize for Physiology and Medicine in 1977, and Schally, in his Nobel lecture, acknowledged the founding contributions of Harris.…”