I. Introduction II. Development A. Embryonic adrenal development B. Fetal adrenal development C. Neonatal adrenal development D. Growth E. Functional development 1. Ontogeny of steroidogenic activity 2. Functional zonation and ontogeny of steroidogenic enzyme expression 3. Responsiveness to ACTH III. Regulation A. The fetal pituitary and ACTH B. Growth factors 1. Basic fibroblast growth factor (bFGF) 2. Epidermal growth factor (EGF) 3. Insulin-like growth factors I and II (IGF-I and IGF-II) 4. Activin/inhibins 5. TGFβ C. Nuclear receptors/transcription factors D. Placental factors 1. Human CG (hCG) 2. Placental CRH and ACTH 3. Indirect effect of placental glucocorticoid metabolism 4. Placental estrogens IV. Physiology A. Placental estrogen formation B. Timing of parturition and fetal maturation V. Summary

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Developmental and functional biology of the primate fetal adrenal cortex.

Publisher Summary Early in fetal life there is relatively autonomous secretion of hypothalamic hypophysiotropic releasing factors and later in development the maturation of inhibitory or restraining influences, mediated via the central nervous system (CNS), modulates pituitary secretion. Even at birth, CNS regulation of pituitary function is incomplete. Therefore, the maturation of CNS control of anterior hypophysial function can be looked upon as a continuum, extending from fetal life into a variable period in infancy and in relation to gonadotropin secretion, into adolescence. This chapter emphasizes on the limitations of measuring pituitary content and serum concentration of hormones in human fetuses obtained largely after therapeutic abortion. It also provides an overview of some of the factors that can influence the plasma concentration of pituitary hormones. The chapter discusses the morphological changes in the hypothalamic-pituitary complex in the fetus, human fetal hypothalamic-hypophysiotropic factors, hypothalamic content and concentration of releasing factors in human fetuses, human fetal pituitary hormones, placental polypeptide hormones, and pituitary hormones in anencephaly. The developmental pattern of secretion of fetal pituitary hormones is not only diverse, but the hormones apparently develop independently of each other.

The ontogenesis of pituitary hormones and hypothalamic factors in the human fetus: maturation of central nervous system regulation of anterior pituitary function.

I. Introduction PHYSIOLOGIC regulation of GH secretion has been an active subject of investigation recently. In particular, the interaction with, and independent functions of, the sex steroid hormones and GH have been the subjects of a large number of studies, both in the basic sciences and in the clinical arena. Based on the results of multiple clinical studies, it has been observed that GH secretion is amplified in the presence of gonadal steroid hormones. During the course of male and female puberty, either normal, precocious, or pharmacologically induced, spontaneously circulating GH levels increase via an amplitude- modulated phenomenon. Using recently available mathematical modeling techniques, it has been possible to demonstrate that the mechanism of this increase is via sex steroid hormone-induced amplification of endogenous GH production rate, without demonstrable alterations of the frequency of secretory episodes or of hormone half-life. We intend to review what is understood about this relation...

The Impact of Gonadal Steroid Hormone Action on Growth Hormone Secretion During Childhood and Adolescence

Mineral and bone metabolism are regulated differently in utero compared with the adult. The fetal kidneys, intestines, and skeleton are not dominant sources of mineral supply for the fetus. Instead...

Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

It is believed that the study of gonadal function of the child should be regarded as a whole beginning with the fetus and ending with the adolescent. Gonadal function depends upon 3 levels of activities: 1) central level (extra-hypothalamic hypothalamic and anterior pituitary); 2) an intermediate level (gonadal and plasma) and 3) a peripheral level consisting of the target organs to which the hormonal message is directed. These activities determine both the expression of gonadal function (physical physiological or psychological) and the feedback regulation of gonadotropin secretion. There are 4 main phases of development of gonadal function: fetal perinatal prepubertal and pubertal. The fetal phase begins with testosterone secretion around the 8th week in utero under the control of the chorionic gonadotropin. Gonadotropin secretion by the pituitary becomes established during the 12th week. During the 2nd half of fetal life negative feedback becomes gradually established appearing more rapidly in boys than in girls. In the perinatal phase the hypothalamic-pituitary activity accounts for the testicular and probably ovarian secretion which has been demonstrated to occur during the 1st 6 months of life. Threshold sensitivity of the gonadostat to steroid inhibition appears high during the 1st 3 months of life progressively declining to the very low level characteristic of childhood. The gonadostat is least active during the prepubertal phase subsequently being more active under the influence of adrenocortical steroids. This hypothalamic activity accounts for the gradual increase of the pituitary and gonadal sensitivity to their respective stimuli. In the pubertal phase the gonadostat threshold rapidly increases and secondary sexual characteristics and reproductive capacity start developing. 2 specific phenomena occur large nocturnal discharges of luteinizing hormone and testosterone and the establishment of positive feedback control by estrogens which permits ovulation.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2265.1976.tb01985.x

Hypothalamic‐pituitary‐gonadal relationships in man from birth to puberty

The hormone synthesis and release in vitro from the adenohypophysis of 40 normal human fetuses was studied by radioimmunoassay and protein incorporation of C14-l-leucine. Within the first 20 days in vitro, the release of GH, prolactin (PRL), LH, FSH, TSH, ACTH and MSH decreased to low or undetectable levels. The production of PRL and MSH, after the initial fall, spontaneously increased with time in culture to sustained and elevated levels. For all the hormones the quantity released was related to the gestational age of the donor fetus. In the cases of LH and FSH the hormonal release was not only related to the age of the fetus but also to the sex. The duration of FSH release in vitro was significantly longer (p > 0.005) for female pituitary cultures than for males. The release of pituitary hormones was detected as early as 5 weeks fetal life. In some fetuses, abnormal release of certain hormones in vitro could be relatd to demonstrable fetal abnormalities. These results indicate that the fetal pi...

L. L. Morgenstern

Papers

Hormone Synthesis and Release from Human Fetal Adenohypophyses in Vitro