Chapter 178. Role of The Hypophysis (pituitary Gland): Physiology and Pathology - Review of Medical Embryology Book

Introduction: all endocrine receptors are dependent on stimulation by the hypophysis after birth. In the fetus, however, some endocrine glands partly or completely function without hypophyseal control

HYPOPHYSECTOMY apparently does not affect fetal growth, which appears to be independent of growth hormone (in contrast to juvenile growth)
ABLATION OF THE FETAL HYPOPHYSIS, experimentally, results in severe atrophy of the thyroid gland and adrenals, but only results in a slowing of gonadal function

IN THE FETUS: hypothalamic control seems less essential than in the adult. Only ACTH secretion appears to require nervous stimulation
IN THE ADULT: all the tropic hormones of the anterior pituitary seem to be generally under hypothalamic nuclear control

The neurosecretion material includes inhibitory and releasing factors
Neurosecretion also includes oxytocin and vasopressin (antidiuretic, ADH) hormones of the posterior pituitary which originate in hypothalamic nuclei

FOLLICLE-STIMULATING HORMONE (FSH): important in the development of the ovarian follicle as well as in spermatogenesis
LUTEINIZING HORMONE (LH) influences testicular endocrine activity after the prenatal period, ovulation, and appearance of the ovarian corpus luteum. Synergistic with FSH
PROLACTIN (LACTOGENIC) HORMONE: postpartum lactation in women. Important for the maintenance of progesterone secretion by the corpus luteum of pregnancy in the rat
THYROTROPIC HORMONE (TSH) stimulates growth and function of the thyroid gland
SOMATOTROPIC ORGROWTH HORMONE (STH) promotes body growth, fat metabolism, and inhibition of glucose utilization
ADRENOCORTICOTROPIC HORMONE (ACTH): development of the fetal adrenal cortex and the primordium of the cortical zone of the definitive cortex

MSH STIMULATES PIGMENT MOVEMENT in the melanophores from cell body to cell processes. Seen in the retinal pigmented epithelium of the mammalian eye

The pineal gland (epiphysis) and hypophyseal relations: its function is antagonistic to the gonadotropic cells of the pituitary in the fetus and in prepubertal children

IF EXPERIMENTALLY DESTROYED or there is a destructive pineal tumor, there is precocious development of the sex organs and secondary sex characteristics
THE ENDOCRINE ROLE of the pineal apparently stops at puberty. Its secretion, melatonin, however, may be involved in the timing of human adolescence

AGENESIS: appears to be the result of a disturbance of notochordal induction
DOUBLING OF THE GLAND: produced experimentally by riboflavin deficiency, hypervitaminosis A, and some tranquilizers
CRANIOPHARYNGIOMAS (Rathke's pouch tumor) constitute about 3-5% of intracranial neoplasms, are usually benign with effects due to pressure, are operable, and especially affect children. Seen intracranially with symptoms like anterior pituitary tumors

Onset of symptoms is usually before the age of 15 years
Usually form in front of the anterior pituitary lobe resulting in visual problems
It is a heterogenous, intrasellar tumor, usually partly solid and partly cystic with keratinized areas and foci of necrosis. Cholesterol crystals and calcification are common. The latter are seen easily on x-rays