1 / 21

The Endocrine System

The Endocrine System. Pituitary Gland The hypophysis (Gr. hypo, under, + physis , growth), or pituitary gland W eighs about 0.5 g It lies in a cavity of the sphenoid bone—the sella turcica —an important radiological landmark

lenka
Download Presentation

The Endocrine System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Endocrine System

  2. Pituitary Gland • The hypophysis (Gr. hypo, under, + physis, growth), or pituitary gland • Weighs about 0.5 g • It lies in a cavity of the sphenoid bone—the sellaturcica—an important radiological landmark • During embryogenesis, the hypophysis develops partly from oral ectoderm and partly from nerve tissue

  3. Because of its dual origin, the hypophysis actually consists of two glands: • Neurohypophysis • Adenohypophysis • They are united anatomically but have different functions. • Neurohypohysis (Posterior Pituitary)neural part. Consists of: • Pars nervosa • Infundibulum(stalk and median eminence)

  4. Adenohypophysis(Anterior Pituitary)glandular part: • It arises from oral ectoderm. • It is subdivided into three portions: • Pars Distalis • Pars Tuberalis • Pars Intermedia.

  5. Adenohypophysis • Pars Distalis(anterior lobe) : • The largest part of adenohypophysis • The main components of the pars distalis are cords of epithelial cells . • Highly vascular stroma. • The hormones produced by these cells are stored as secretory granules. • Fibroblasts produce reticular fibers that support the cords of hormone-secreting cells.

  6. The pars distalis accounts for 75% of the mass of the hypophysis. • Common stains allow the recognition of three cell types in the pars distalis: • Chromophobes(Gr. chroma, color, + phobos, fear) • Chromophils(Gr. chroma + philein, to love) • Two types of chromophils: • Basophils according to their affinity for basic dyes • Acidophilsaccording to their affinity for acid dyes • The subtypes of basophil and acidophil cells are named for the hormones they produce. • With the exception of the gonadotropic cell, which produces two hormones, the other cells produce only a single hormone. • Chromophobes(degranulated secretory cells) do not stain intensely and, when observed with an electron microscope, show two populations of cells.

  7. Secretory Cells of the Pars Distalis

  8. Pars Tuberalis • The pars tuberalis is a funnel-shaped region surrounding the infundibulum of the neurohypophysis . • Most of the cells secrete gonadotropins (follicle-stimulating hormone and luteinizing hormone) • Are arranged in cords alongside the blood vessels.

  9. Pars Intermedia • Is a rudimentary region in humans • Made up of cords and follicles of weakly basophilic cells that contain small secretory granules. • It produces Melanocyte-stimulating hormone (α-MSH).

  10. Neurohypophysis (Posterior pituitary) • It consists of • Pars nervosa • Infundibulum (neural stalk)stem and median eminence.that connects it to the hypothalamus.

  11. The pars nervosa • Does not contain secretory cells. • Contains nonmyelinated axons and nerve endings of neurosecretoryneuron • The nerve endings have terminal dilations called Herring bodies

  12. Pars Nervosa Neurosecretoryneurons have cell bodies that lie in the supraoptic & paraventricularnuclei in the hypothalamus The secretory neurons have all the characteristics of typical neurons The secretory neurons have well-developed Nissl bodies related to the production of the neurosecretory material Cells present in Pars Nervosa are: Pituicytes(glial cell) fibroblasts mast cells.

  13. Adrenal Glands • This gland is found above the kidney. • The dense connective tissue capsule covers the adrenal gland & sends thin septae into the gland. • Septae support the blood vessels and nerves • The stroma consists mainly of a rich network of reticular fibers that supports the secretory cells. • The parenchyma consists of cortex and medulla.

  14. The cortex is subdivided into 3 concentric zones, according to the arrangement of the cells these zones are called: i.ZonaGlomerulosa. ii. ZonaFasiculata. The cells in this zone are called spongiocyes. iii. ZonaReticularis.

More Related