Hypothalamic–pituitary–gonadal axis Much of the research is done on animal models, because they mimic so well the control mechanism of humans. It is important to remember humans are the only species to hide their fertile period, but this effect is a difference in the effect of the hormones rather than a difference in the HPG axis. Hypothalamic–pituitary–gonadal axis The hypothalamic–pituitary–gonadal axis (HPG axis) refers to the hypothalamus, pituitary gland, and gonadal glands as if these individual endocrine glands were a single entity. Because these glands often act in concert, physiologists and endocrinologists find it convenient and descriptive to speak of them as
Pituitary gland 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. The anterior pituitary contains several different types of cells that synthesize and secrete hormones. Usually there is one type of cell for each major hormone formed in anterior pituitary. With special stains attached to high-affinity antibodies that bind with distinctive hormone, at least 5