Changes

The gland is divided into '''anterior and posterior''', with different embryological origins reflecting a difference in function:

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 '''antidiuretic hormone (ADH)'''.

*'''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 '''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''. 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.  

*'''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 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 [[Prohormones - Anatomy & Physiology|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 - Anatomy & Physiology|hypothalamus]].

*'''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 [[Prohormones - Anatomy & Physiology|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 - Anatomy & Physiology|hypothalamus]].

==Thyroid Gland==

==Thyroid Gland==