Hormones secreted from the pituitary gland help control the following body processes:
The anterior pituitary synthesizes and secretes hormones. All releasing hormones (-RH) referred to, can also be referred to as releasing factors (-RF). These hormones are released from the anterior pituitary under the influence of the hypothalamus. Hypothalamic hormones are secreted to the anterior lobe by way of a special capillary system, called the hypothalamic-hypophysial portal system (Pic. 1).
The intermediate lobe synthesizes and secretes the following important endocrine hormone:
The posterior pituitary is actually an extension of the neurons of the paraventricular and supraoptic nuclei of the hypothalamus. The cell bodies of these regions rest in the hypothalamus, but their axons descend as the hypothalamic–hypophyseal tract within the infundibulum, and end in axon terminals that comprise the posterior pituitary (Pic. 4). The posterior pituitary stores and secretes (but does not synthesize) the following important endocrine hormones:
The anterior pituitary is derived from the ectoderm, more specifically from that of Rathke’s pouch, part of the developing hard palate in the embryo. The pouch eventually loses its connection with the pharynx, giving rise to the anterior pituitary. The anterior wall of Rathke's pouch proliferates, filling most of the pouch to form the pars distalis and the pars tuberalis. The posterior wall of the anterior pituitary forms the pars intermedia. Its formation from the soft tissues of the upper palate contrasts with the posterior pituitary, which originates from neuroectoderm.
The pituitary gland is an endocrine gland about the size of a pea and weighing 0.5 grams in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The hypophysis rests upon the hypophysial fossa of the sphenoid bone in the center of the middle cranial fossa and is surrounded by a small bony cavity (sella turcica) covered by a dural fold (diaphragma sellae) (Pic. 5 and Pic. 6).
It consists of two lobes that arise from distinct parts of embryonic tissue:
The anterior pituitary is composed of three regions:
Microanatomy of the pars distalis showing chromophobes, basophils and acidophils The pars distalis, (distal part), comprises the majority of the anterior pituitary and is where the bulk of pituitary hormone production occurs.
The pars distalis contains two types of cells including:
These cells all together produce hormones of the anterior pituitary, and release them into the blood stream.
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. The function of the pars tuberalis is poorly understood. However it has been seen to be important in receiving the endocrine signal in the form of TSHB (a β subunit of TSH) informing the pars tuberalis of the photoperiod (length of day).
The expression of this subunit is regulated by the secretion of melatonin in response to light information transmitted to the pineal gland.
The pars intermedia, (intermediate part), sits between the pars distalis and the posterior pituitary, forming the boundary between the anterior and posterior pituitaries. It is very small and indistinct in humans.
The posterior pituitary gland does not produce hormones, but rather stores and secretes hormones produced by the hypothalamus. The paraventricular nuclei produce the hormone oxytocin, whereas the supraoptic nuclei produce ADH. These hormones travel along the axons into storage sites in the axon terminals of the posterior pituitary. In response to signals from the same hypothalamic neurons, the hormones are released from the axon terminals into the bloodstream.
The absence of a menstrual period in women of reproductive age.
An eating disorder characterized by the maintenance of a body weight below average, fear of gaining weight, and a distorted body image.
Failure of the ovaries to release an oocyte over a period of time generally exceeding 3 months.
Complete absence of sperm in the ejaculate of a man.
A man's inability for or persistent difficulty in achieving orgasm, despite typical sexual desire and sexual stimulation.
The inability (that lasts more than 6 months) to develop or maintain an erection of the penis during sexual activity.
The presence of abnormally high levels of prolactin in the blood.
A medical term which describes a diminished functional activity of the gonads – the testes and ovaries.
Partial or complete loss of production of one or more of the pituitary gland hormones.
A genetic condition where the primary symptom is a failure to start puberty or a failure to fully complete puberty.
The set of symptoms that result from two or more X chromosome in males.
The time in most women's lives when menstrual periods stop permanently, and the woman is no longer able to have children.
An abnormal condition in a woman's menstrual cycle.
Complete absence of sperm in the ejaculate due to testicular failure.
Semen with a low concentration of sperm and is a common finding in male infertility.
A condition in which a woman has an imbalance of female sex hormones. This may lead to changes in the menstrual cycle, cysts in the ovaries, trouble g
The inability of the testicles to produce sperm or testosterone.
Emergency medical condition occurring when the spermatic cord twists and cuts off the testicle's blood supply.
A medical condition impairing the function of the thyroid.
In the case of cryptorchidism one or both testes are absent from the scrotum. It is is the most common etiologic factor of azoospermy in the adult.
FSH is a hormone secreted by the anterior pituitary gland. It regulates the development, growth, pubertal matur and reproductive functions of the body
A complex set of direct influences and feedback interactions among two endocrine glands: the hypothalamus, and the pituitary gland.
An anovulatory cycle is a menstrual cycle during which the ovaries do not release an oocyte.
A condition with high serum follicle–stimulating hormone (FSH) concentration.
The failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse.
Irregular menstruation is a menstrual disorder whose manifestations include irregular cycle lengths as well as metrorrhagia
The age at onset of first menstruation.