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The pituitary gland or pituitary gland ( hypophysis , glandula pituitaria ) is a endocrine Gland which is in a small osseous cavity at the base of the Cerveau, the turcic Selle ( sella turcica ). It is connected to another part of the brain called the Hypothalamus. It produces Hormone S which manage a broad range of body functions, of which the trophic hormones which stimulate other endocrine glands. This function inspired the scientists to call it “main gland” of the body, but today it is known that the pituitary gland is controlled by the hormones (neurohormones) emitted by the hypothalamus.

This body exists in its typical form at all the vertebrate ones.

Subdivisions

The pituitary gland is divided into two lobes: the Ante-pituitary gland (adénohypophyse) ahead, and the post-pituitary gland (Neurohypophyse) behind. The adénohypophyse drift of the ceiling of the primitive oral cavity (stomodeum), while the post-pituitary gland is an extension of the hypothalamus, connected to this one by the pituitary stem, and contains the axons of neurons whose cellular bodies are in the hypothalamus. One can also find between the ante-pituitary gland and the post-pituitary gland, a third structure, the intermediate pituitary gland, developed well at certain animal species: at the man, the intermediate pituitary gland is only visible in fetal period and until the age of ten or twenty years; in the adult, there remains some cystic structures.

Embryology

It is formed by the welding of two invaginations:
  • the infundibulum coming from diencephalon (the post-pituitary gland gives)
  • the pocket of Rathke coming from the oral cavity (the handle-pituitary gland gives)

The ante-pituitary gland

See also: Ante-pituitary gland

The ante-pituitary gland contains many different cellular types which secrete each one one or more following Hormones:

In the event of defect of production, one speaks about Hypopituitarisme (Insuffisance antéhypophysaire). It can be a question of a deficit of one or more hormones (somatotropic insufficiency isolated in the child for example, resulting in a delay of growth). The hypersecretion is generally due to a Adénome. The adenomata are by order of frequency:

  • adenoma lactotrope (secretion of Prolactine from where Hyperprolactinémie)
  • somatotropic adenoma (secretion of GH from where Acromégalie)
  • adenoma gonadotrope or not-secreting (synthesis of LH and FSH, not always released in blood)
  • adenoma corticotrope (secretion of ACTH from where Syndrome of Cushing)
  • adenoma thyréotrope (very rare, Hyperthyroïdie by excess of TSH)
  • there exist mixed adenomata: somatotropic and lactotrope especially, but of other associations is possible.

One speaks about micro adenoma (less than 1 cm) or about macro hypophyseal adenoma (more than 1 cm).

A macro adenoma can provide an excess of hormone (S) and, in same time, compress the healthy pituitary gland, involving a deficit of one or more other hormones.

The Ante-pituitary gland is formed starting from a dorsal diverticulum of the primitive mouth: this outline is called the Pocket of Rathke, made up of a former layer (future ante-pituitary gland), of a posterior layer (future intermediate pituitary gland), and of a central area, the hypophyseal slit.

The post-pituitary gland

The post-pituitary gland or neurohypophyse is in fact a projection of the Hypothalamus. It does not produce its own hormones; it does nothing but store and distribute the hormones Ocytocine and Vasopressine in the form of Neurosécrétion S.

It is formed starting from a projection of the floor of the diencephalon, which will give the hypothalamus and the post-pituitary gland, connected by the pituitary stem. This outline tends to approach the outline of the antéhypophyse, then amalgamates with It during the fetal period.

Simple: Pituitary nipple

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