Hypothalamic–pituitary–gonadal axis controls development, reproduction, and aging in animals. Gonadotropin-releasing hormone (GnRH) is secreted from the hypothalamus by GnRH-expressing neurons. The anterior portion of the pituitary gland produces luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonads produce estrogen and testosterone. In oviparous organisms (e.g. fish, reptiles, amphibians, birds), the HPG axis is commonly referred to as the hypothalamus-pituitary-gonadal-liver axis (HPGL-axis) in females. Many egg-yolk and chorionic proteins are synthesized heterologously in the liver, which are necessary for oocyte growth and development. Examples of such necessary liver proteins are vitellogenin and choriogenin. The HPA, HPG, and HPT axes are three pathways
Pituitary gland referred to the pituitary gland by only using the (Ancient Greek) name ἀδήν, "gland". He described the pituitary gland as part of a series of secretory organs for the excretion of nasal mucus. Anatomist Andreas Vesalius translated ἀδήν with "glans, in quam pituita destillat", "gland in which slime ("pituita") drips". Besides this 'descriptive' name, Vesalius used "glandula pituitaria", from which the English name "pituitary gland" is ultimately derived. The expression "glandula pituitaria" is still used as official synonym beside "hypophysis" in the official Latin nomenclature "Terminologia Anatomica". In the seventeenth century the supposed function of the pituitary gland to produce