<P> The pituitary gland, in humans, is a pea - sized gland that sits in a protective bony enclosure called the sella turcica . It is composed of three lobes: anterior, intermediate, and posterior . In many animals, these three lobes are distinct. The intermediate is avascular and almost absent in human beings . The intermediate lobe is present in many lower animal species, in particular in rodents, mice and rats, that have been used extensively to study pituitary development and function . In all animals, the fleshy, glandular anterior pituitary is distinct from the neural composition of the posterior pituitary, which is an extension of the hypothalamus . </P> <P> The anterior pituitary arises from an invagination of the oral ectoderm and forms Rathke's pouch . This contrasts with the posterior pituitary, which originates from neuroectoderm . </P> <P> Endocrine cells of the anterior pituitary are controlled by regulatory hormones released by parvocellular neurosecretory cells in the hypothalamic capillaries leading to infundibular blood vessels, which in turn lead to a second capillary bed in the anterior pituitary . This vascular relationship constitutes the hypothalamo - hypophyseal portal system . Diffusing out of the second capillary bed, the hypothalamic releasing hormones then bind to anterior pituitary endocrine cells, upregulating or downregulating their release of hormones . </P> <P> The anterior lobe of the pituitary can be divided into the pars tuberalis (pars glandularis) and pars distalis (pars glandularis) that constitutes ~ 80% of the gland . The pars intermedia (the intermediate lobe) lies between the pars distalis and the pars tuberalis, and is rudimentary in the human, although in other species it is more developed . It develops from a depression in the dorsal wall of the pharynx (stomal part) known as Rathke's pouch . </P>

What hormones are controlled by the pituitary gland