Hypophysis Pars intermedia

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. 

Melanocortin peptides, melanocortins, melanocyte-stimulating hormone, MSH, melanotropin, a peptide hormone produced in the pars intermedia of the hypophysis under the control of melanoliberin and melanostatin. Species lacking the... 

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. 

During its organogenesis, the hypophysis leaves tracks in an area between the pharynx and the hypophysis. Again, small epithelial nodules of hypophyseal cells are inserted within the mucosa. These residues of embryological structures may develop into hypophyseal tumors that are found in the roof of the nasopharynx, in the body of the sphenoid bone, in the capsule of the pituitary gland, within the pars intermedia, and around the infundibulum. Such tumors are most frequently found in the pituitary capsule and the infundibulum. 

Distribution of Cadmium in the Central Nervous System After Parenteral or Oral Administration, walsh and Burch studied the distribution of ""Cd in normal dogs after intravenous injection and found no uptake in the brain, phrenic nerve, or brachial plexus up to 48 h after the injection. Autoradiographic studies with intravenously administered ° Cd revealed only traces of cadmium in the brain parench3mia, whereas pronounced accumulation was seen in the pia mater, choroid plexus, and hypophysis. " Within the pituitary, the pars intermedia contained less cadmium than the rest of the gland. " Arvidson and Tjalve found accumulation of ""Cd also in the pineal gland of rats 1 week after intravenous injection (Figs. 6, 7). 

The pituitary body, or hypophysis, is double in origin and multiple in functions. From the stomodceal pouch of Rathke is developed the anterior lobe and the -pars intermedia from the floor of the third ventricle are formed the pars nervosa of the posterior lobe, the infundibulum and the tuber cinereum. The pituitary autacoids are of two types secretions acting directly on other tissues, and hormo-kinetic secretions acting indirectly by stimulating other endocrine glands. 

The hypophysis (pituitary gland) is an accessory gland of the brain. It consists of two anatomically distinct organs, the anterior lobe and the posterior lobe, and each lobe elaborates several different hormones. A middle lobe (pars intermedia developed to different extents in different animals), produces another hormone. The second part of Table XVIII (Section 1) lists all the different hypophyseal hormones. Many hormones of the anterior lobe are master hormones (Section 1). 

Middle Lobe of the Hypophysis. The middle lobe (or pars intermedia) produces melanotropin. Its chemical constitution is known, but it has been prepared in pure form only recently (A. B. Lerner C. H. Li). It closely resembles corticotropin (cf. the reverse side of the fold-out chart at the end of the volume). 

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