Hypophysis

The hypophysis is a small, bean-shaped organ (0.6-0.65 g) located in the sella turcica at the base of the skull. On close examination of the gland, an anterior yellowish and a posterior more fibrous and whitish part can be distinguished. The two parts are separated by a pars intermedia, a lamellar structure, grayish and fibrous in appearance. The gland is attached to the floor of the third ventricle by a hollow pedicle, the stalk of the hypophysis. 

The anterior lobe of the hypophysis (70-80% of the total weight of the gland) is made of several types of cells that are arranged in long columns forming a complex network. The meshes of the network are filled with small amounts of connective tissue and large capillaries. In some areas of the anterior lobe close to the pars intermedia, these cells are arranged to form pedicles that contain a colloid material. 

The size of the pars tuberalis of the hypophysis varies considerably depending upon the species. It is large in the cat and dog and small in humans. The pars tuberalis is made of glandular chords that form vesicles containing colloid material. In contrast to the pars intermedia, the pars tuberalis contains many capillaries and neurofibers. 

The pars nervosa is made of neuroglial cells and nervous fibers that are most abundant in the stalk of the pituitary. The pars nervosa contains three different types of cells that cannot be distinguished with ordinary staining techniques. The posterior lobe of 

From the floor of the midbrain, another evagination develops. It takes the form of a hollow diverticulum called the infundibulum. In the fourth week of intrauterine life of the human embryo, the infundibular and entoblastic proliferations join to form the hypophysis. The histogenesis of the hypophysis is usually completed in the ninth month of pregnancy. 

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GeMm, n. brain. — kleines —, cerebellum. Gehirn-. cerebral, -auhang, m. pitmtary body, hypophysis, -entztinduiig, /. encephalitis, -fett, n. cerebrin. 

Heparin was immobilized on the WPG-P A and the sorbent was used for isolation of the fibroblast growth factor from bovine hypophysis. Mitogenic activity of the factor purified on the heparin-WPG-PA and Heparin-Sepharose, as estimated with mice fibroblasts of line N1H-3T3, was virtually the same [130]. 

In central diabetes insipidus a hypophysial malfunction, caused by different diseases as well as head injuries, neurosurgery, or genetic disorders, leads to AVP hyposecretion. This type of diabetes insipidus can successfully be treated by the exogenous administration of AVP or AVP analogues (e.g. desmopressin). 

Krzymowski T., Grzegorzewski W., Stefanczyk-Krzymowska S., Skipor J., et al. (1999). Humoral pathway for transfer of the boar pheromone androstenol, from the nasal mucosa to the brain and hypophysis of gilts. Theriogenol 52, 1225-1240. 

The pituitary gland, or hypophysis, is located at the base of the brain just below the hypothalamus. It is composed of two functionally and anatomically distinct lobes (see Figure 10.2) ... 

Jouvet, M. (1988). The regulation of paradoxical sleep by the hypothalamo-hypophysis. Arch. Ital. Biol. 126, 259-74. 

P. E. Belchetz, T. M. Plant, Y. Nakai, E. J. Keogh, and E. Knobil, Hypophysial responses to continuous and intermittent delivery of hypothalamic gonadotropin-releasing hormone. Science 202, 631-633 (1978). 

Effect of glucocorticoid administration on adrenocortical cortisol production (A). Release of cortisol depends on stimulation by hypophyseal ACTH, which in turn is controlled by hypothalamic corticotropin-releasing hormone (CRH). In both the hypophysis and hypothalamus there are cortisol receptors through which cortisol can exert a feedback inhibition of ACTH or CRH release. 

In a hyperfunctioning of the thyroid gland, secretion of an excess quantity of thyroid hormones leads to a hyperthyroid condition (Basedow s disease, goiter). In this condition, drags are used that suppress production of thyrotropic hormones in the anterior lobe of the hypophysis (diiodotyrosine), in the thyroid gland (propylthiouracil, methylthiouracil,... 

Drugs used for hyperthyroidism can be classified as drugs that suppress thyroid hormone synthesis in the anterior lobe of the hypophysis, and they consist of diiodotyrosine and iodine, as well as drugs that suppress thyroid hormone synthesis in thyroid glands (propylthiouracil, methylthiouracil, methimazole, and carbimazole). 

Diiodotyrosine does not possess pronounced hormonal activity. However, it stops production of thyrotropic hormone by the anterior lobe of the hypophysis, which activates thyroid gland activity. 

Formation of these drugs is under the direct control of a polypeptide adrenocorticotropic hormone (ACTH, corticotropin), which is processed by the anterior lobe of the hypophysis. Human ACTH consists of 39 amino acids and has a molecular weight of about 4500. It differs from animal ACTH in the amino acid compositions at positions 29-33. 

The biosynthesis and secretion of a hormone is regulated by a number of mechanisms and they themselves are involved in complex regulatory schemes. An informative example is the hierarchically ordered hypothalamus-hypophysis system which regulates the biosynthesis and secretion of many hormones of the nuclear receptors. 

Phytoestrogens seem to alter the sexual development of animals by acting on the hypothalamic system of hypophysial regulation60 (in spite of the results of other authors61). 

Endostome processes opposite the teeth of the exostome, either free or united with them, but the peristome sometimes entirely wanting hypophysis sometimes highly developed acrocarpous mosses.Order Splachnales (Funariales)... 

The hypothalamus, a four gram portion of the brain, receives a great deal of biochemical attention because of its function in the autonomic nervous system, in homeostasis, and in endocrine secretion. Its liberation of neurohormones that stimulate the hypophysis has already been considered in Section A,3. The hypothalamus is also involved in the regulation of the body temperature, of water balance, and possibly of glucose concentration. 

Pituitary Hormones. The hormones of the hypophysis (pituitary gland) are quite numerous, being secreted variously in three parts of the gland — the ncurohypophysis (posterior lobel. the adenohypophysis (anterior lithe), and the pars intermedia, which connects the other two. 

In biopolymers hydrates may enforce special conformations141. For example, the harmone oxy tocine of the hypophysis conforms with all hydrophobic groups on one side1271 (Fig. 26) and the hydrophilic groups on the other12 (Fig. 27). Similarity the A-chain and the B-chain of insulin can be arranged to form a disc with a... 

HCG was combined with Clomiphene (Clomid) sometimes, or Clomiphene was used after HCG administration. This is because Clomiphene acts by affecting the hypothalamus and pituitary (hypophysis) and regenerating the whole regulating system, while HCG only "imitates" LH, thus stimulating the leydig cells in the testes to produce natural testosterone. ( Also see HCG)... 

Posterior Lobe. The posterior pituitary, or neuro-hypophysis, secretes two hormones antidiuretic hormone (ADH) and oxytocin.2 12 ADH exerts its effect... 

The effects of treatment with selegiline, an MAO-B inhibitor, on plasma levels of insulin-like growth factor I (IGF-I) (as indicator of GH secretion), levels of monoamines and their metabolites, and the activity and content of tyrosine hydroxylase — the rate-limiting enzyme in the biosynthesis of catecholamines — in the hypothalamus and hypophysis of old animals have been studied. It is believed that the antiaging effects of selegiline are due to restoration of hypothalamic hormones. 

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