The anterior wall of Rathke's pouch proliferates, filling most of the pouch to form the pars distalis and the pars tuberalis. The pouch eventually loses its connection with the pharynx, giving rise to the anterior pituitary. RathkeвЂ™s pouch is also ectodermal in origin. The anterior pituitary is derived from the ectoderm, more specifically from that of RathkeвЂ™s pouch, part of the developing hard palate in the embryo. It is very small and indistinct in humans. Pars intermedia The pars intermedia (intermediate part) sits between the pars distalis and the posterior pituitary, forming the boundary between the anterior and posterior pituitaries.

Earlier studies have shown localization of melatonin receptors in this region. The expression of this subunit is regulated by the secretion of melatonin in response to light information transmitted to the pineal gland. However, it has been seen to be important in receiving the endocrine signal in the form of TSHB (a ОІ subunit of TSH), informing the pars tuberalis of the photoperiod (length of day). (The pituitary stalk connects the hypothalamus to the posterior pituitary.) The function of the pars tuberalis is poorly understood. Pars tuberalis The pars tuberalis (tubular part) forms a part of the sheath extending up from the pars distalis, which joins with the pituitary stalk (also known as the infundibular stalk or infundibulum), arising from the posterior lobe. This is due to the possible confusion with white blood cells, where one may also find basophils and acidophils.Д®osinophilic follicles are a common normal finding in the anterior pituitary. Nota bene: The terms 'basophil' and 'acidophil' are used by some books, whereas others prefer not to use these terms. These cells all together produce hormones of the anterior pituitary and release them into the blood stream. The chromophils can be further divided into acidophils (alpha cells) and basophils (beta cells). The pars distalis contains two types of cells, including chromophobe cells and chromophil cells. The pars distalis (distal part) comprises the majority of the anterior pituitary and is where the bulk of pituitary hormone production occurs. The anterior pituitary is composed of three regions: In all animals, the fleshy, glandular anterior pituitary is distinct from the neural composition of the posterior pituitary. However, in humans, the intermediate lobe is but a few cell layers thick and indistinct as a result, it is often considered part of the anterior pituitary. In many animals, these lobes are distinct. It is composed of three lobes: the anterior, intermediate, and posterior lobes. The pituitary gland sits in a protective bony enclosure called the sella turcica ( Turkish chair/saddle).

Anterior pituitary gland hormones