12th April 2024

Posterior pituitary

The pituitary gland consists of the anterior and posterior pituitary glands. It is a direct continuation of the hypothalamus connected by the infundibulum (pituitary stalk) and rests on the sella turcica below the optic chiasm. The posterior pituitary gland, also known as the neurohypophysis, arises from the neural ectoderm at the floor of the forebrain. It is supplied by the inferior hypophyseal artery and drains into the inferior hypophyseal vein. The pituitary gland does not produce hormones; it stores them. The two hormones, vasopressin and oxytocin, are synthesised in the hypothalamus and released from the posterior pituitary gland directly into the systemic circulation.  In the hypothalamus, the paraventricular nuclei primarily produces oxytocin and the supraoptic nuclei primarily produces vasopressin. The posterior pituitary gland is made up of axons extending from neuronal cell bodies in the paraventricular and supraoptic nuclei located in the hypothalamus.   

Table 1: summarising the hormones synthesised in the hypothalamus and released by the posterior pituitary gland to act on their target organs

Image Source: Wikimedia Commons (2013). The_Hypothalamus-Pituitary_Complex, Licensed under a creative commons licence. Available for free at: https://en.m.wikipedia.org/wiki/File:1806_The_Hypothalamus-Pituitary_Complex.jpg (Accessed: 11 April 2024).

Image Source: Wikimedia Commons (1918). Anterior_pituitary, Licensed under a creative commons licence.

https://en.wikipedia.org/wiki/Anterior_pituitary#/media/File:Gray1180.png(Accessed: 11 April 2024).