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Equine Endocrine System - Horse Anatomy (view source)
Revision as of 11:42, 19 November 2012
, 11:42, 19 November 2012→Pituitary Gland
==Hypothalamus==
==Hypothalamus==
==Pituitary Gland==
==Pituitary Gland==
The pituitary gland, or ''hypophysis'' is an elongated appendage of the brain lying within a bony cavity of the [[Skull and Facial Muscles - Anatomy & Physiology#Sphenoid Bone (os sphenoidale)|sphenoid bone]] in the base of the skull - the '''Sella Turcica'''. The hypophysis is suspended ventral to the the [[Hypothalamus - Anatomy & Physiology|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 - Anatomy & Physiology|hypothalamus]]. As such, it is a collection of axons and nerve terminals that originate in the paraventricular and superoptic nuclei of the [[Hypothalamus - Anatomy & Physiology|hypothalamus]]. The pars nervosa stores and releases '''oxytocin''' and '''arginine vasopressin'''.
*'''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''. 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 endocrine cells within the pars distalis synthesize, store and release 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.
*'''Pars Intermedia''': This part separates the anterior and posterior lobes.
==Thyroid Gland==
==Thyroid Gland==
==Parathyroid Glands==
==Parathyroid Glands==
==Adrenal Glands==
==Adrenal Glands==
==Pineal Glands==
==Pineal Glands==