Difference between revisions of "Equine Endocrine System - Horse Anatomy"
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The pars nervosa stores and releases '''oxytocin''' and '''antidiuretic hormone (ADH)'''. | The pars nervosa stores and releases '''oxytocin''' and '''antidiuretic hormone (ADH)'''. | ||
===Anterior pituitary(Adenohypophysis)=== | ===Anterior pituitary(Adenohypophysis)=== | ||
| − | Consisting of the '''Pars Tuberalis and Pars Distalis''' this part has an embryological origin as an epithelial upgrowth from the foetal oral cavity called '''Rathke's Pouch''' | + | Consisting of the '''Pars Tuberalis and Pars Distalis''' this part has an embryological origin as an epithelial upgrowth from the foetal oral cavity called '''Rathke's Pouch'''. |
====Pars Tuberalis==== | ====Pars Tuberalis==== | ||
The pars tuberalis is a thin band of endocrine cells around the infundibular stalk. It is dense in '''melatonin''' receptors, and functions to regulate release of reproductive hormones according to season. | The pars tuberalis is a thin band of endocrine cells around the infundibular stalk. It is dense in '''melatonin''' receptors, and functions to regulate release of reproductive hormones according to season. | ||
====Pars Distalis==== | ====Pars Distalis==== | ||
| − | The pars distalis contains five cell types (somatotropes, lactotropes, corticotropes, thyrotropes and gonadotropes). The endocrine cells within the pars distalis synthesize, store and release six hormones in response releasing and inhibiting factors from the [[Hypothalamus - Anatomy & Physiology|hypothalamus]]. These factors reach the pars distalis in the '''hypophyseal portal system''', which connects capillaries of the median eminence to the capillaries of the pars distalis. | + | The pars distalis contains five cell types (somatotropes, lactotropes, corticotropes, thyrotropes and gonadotropes). The endocrine cells within the pars distalis synthesize, store and release six hormones in response releasing and inhibiting factors from the [[Hypothalamus - Anatomy & Physiology|hypothalamus]]. These factors reach the pars distalis in the '''hypophyseal portal system''', which connects capillaries of the median eminence to the capillaries of the pars distalis. The hormones produced are '''growth hormone (GH)''', '''follicle stimulating hormone (FSH)''', '''luteinising hormone (LH)''', '''adrenocorticotrophic hormone (ACTH)''', '''thyroid stimulating hormone (TSH)''' and '''prolactin (PRL)'''. For further information on each of these hormones, click [[Pituitary Gland - Anatomy & Physiology#Hormones of the Anterior Pituitary Gland|here]]. |
===Pars Intermedia=== | ===Pars Intermedia=== | ||
Revision as of 12:09, 19 November 2012
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This article is still under construction. |
Hypothalamus
Pituitary Gland
The pituitary gland, or hypophysis is an elongated appendage of the brain lying within a bony cavity of the sphenoid bone in the base of the skull - the Sella Turcica. The hypophysis is suspended ventral to the the hypothalamus by a thin infundibular stalk. It lies between the more rostral optic chiasma, and the more caudal mammillary bodies, separated from the brain by a fold of dura mater known as the diaphragma sellae. The gland is divided into anterior and posterior, with different embryological origins reflecting a difference in function.
Posterior pituitary(Neurohypophysis)
Consisting of the Pars Nervosa, this section is derived from a downgrowth of neural tissue from the hypothalamus. As such, it is a collection of axons and nerve terminals that originate in the paraventricular and superoptic nuclei of the hypothalamus. The pars nervosa stores and releases oxytocin and antidiuretic hormone (ADH).
Anterior pituitary(Adenohypophysis)
Consisting of the Pars Tuberalis and Pars Distalis this part has an embryological origin as an epithelial upgrowth from the foetal oral cavity called Rathke's Pouch.
Pars Tuberalis
The pars tuberalis is a thin band of endocrine cells around the infundibular stalk. It is dense in melatonin receptors, and functions to regulate release of reproductive hormones according to season.
Pars Distalis
The pars distalis contains five cell types (somatotropes, lactotropes, corticotropes, thyrotropes and gonadotropes). The endocrine cells within the pars distalis synthesize, store and release six hormones in response releasing and inhibiting factors from the hypothalamus. These factors reach the pars distalis in the hypophyseal portal system, which connects capillaries of the median eminence to the capillaries of the pars distalis. The hormones produced are growth hormone (GH), follicle stimulating hormone (FSH), luteinising hormone (LH), adrenocorticotrophic hormone (ACTH), thyroid stimulating hormone (TSH) and prolactin (PRL). For further information on each of these hormones, click here.
Pars Intermedia
This is the residual lumen of Rathke's Pouch and consists of a series of small cystic cavities (follicles filled with colloid), with both basophillic and chromatophobic (poorly staining) cell types. These extend into the pars nervosa.T The pars intermedia separates the anterior and posterior lobes. Endocrine cells in this region are known as melanotropes. These convert the prohormone pro-opiomelanocorticotropin (POMC) to melanocyte stimulating hormone (a-MSH) and corticotropin-like intermediate lobe peptide (CLIP). The pars intermedia is innervated by dopaminergic neurones originating in the periventricular nucleus of the hypothalamus.