Adenohypophysis

[ "article:topic", "hypothalamus", "antidiuretic hormone (ADH)", "pituitary gland", "oxytocin", "osmoreceptor", "prolactin (PRL)", "pituitary dwarfism", "luteinizing hormone (LH)", "insulin-like growth factors (IGF)", "infundibulum", "hypophyseal portal system", "growth hormone (GH)", "gonadotropins", "gigantism", "follicle-stimulating hormone (FSH)", "adrenocorticotropic hormone (ACTH)", "acromegaly", "license:ccby", "showtoc:no", "source[1]-med-736", "source[2]-med-736", "program:oeri", "authorname:humananatomyoeri" ] By the end of this section, you will be able to: • Explain the interrelationships of the anatomy and functions of the hypothalamus and the posterior and anterior lobes of the pituitary gland • Identify the two hormones released from the posterior pituitary, their target cells, and their principal actions • Identify the six hormones produced by the anterior lobe of the pituitary gland, their target cells, their principal actions, and their regulation by the hypothalamus The hypothalamus–pituitary complex can be thought of as the “command center” of the endocrine system. This complex secretes several hormones that directly produce responses in target tissues, as well as hormones that regulate the synthesis and secretion of hormones of other glands. In addition, the hypothalamus–pituitary complex coordinates the messages of the endocrine and nervous systems. In many cases, a stimulus received by the nervous system must pass through the hypothalamus–pituitary c...

The pituitary gland is a small endocrine organ located within the sella turcica. Various pathologic conditions affect the pituitary gland and produce endocrinologic and neurologic abnormalities. The most common lesion of the pituitary gland is the adenoma, a benign neoplasm. Dedicated MR imaging of the pituitary is radiologic study of choice for evaluating pituitary gland and central skull region. Computed tomography is complimentary and allows for identification of calcification and adjacent abnormalities of the osseous skull base. This review emphasizes basic anatomy, current imaging techniques, and highlights the spectrum of pathologic conditions that affect the pituitary gland and sellar region. Key points • • MR imaging is the study of choice for evaluating primary tumors and other lesions of the pituitary gland and the central skull base region. • • CT is complimentary in evaluating pituitary and other sellar masses given its ability to detect calcification and assess osseous involvement of skull base. • • The adenoma is the most common lesion of the pituitary gland and can be symptomatic because of its endocrine effects or localized mass effect. • • Macroadenomas can have a variety of imaging appearances based on size, cystic/necrotic change, extent of local invasion, and post-treatment effects. • • There is a broad spectrum of disorders that should be considered in the radiologic evaluation of pituitary, sellar, and suprasellar masses. Introduction The pituitary gl...

The pituitary gland (hypophysis) along with the associated hypothalamus of the brain, form a major regulatory system of the body. The pituitary gland is often called the master gland because it regulates numerous physiological systems, with many of its hormones targeting other endocrine organs. The hypophysis consists of two portions, the neurohypophysis and the adenohypophysis. Hypothalamus > The hypothalamus (black arrow) of the brain exerts a major controlling influence over the pituitary gland. Hypothalamic neurons either directly produce neurohypophyseal hormones or indirectly stimulate or inhibit the production of adenohypophyseal hormones via a vascular connection. The optic chiasm (red arrow) is shown for reference. Neurohypophysis > The neurohypophysis (posterior pituitary) forms embryologically as an evagination of the hypothalamus and remains directly connected to it. The neurohypophysis consists of the pars nervosa, the infundibulum and its continuation, the median eminence. Hypothalamic neurons terminating in the neurohypophysis store and release vasopressin and oxytocin. - Secretion > Axons (red arrows) of neurons originating in supraoptic and paraventricular nuclei (blue arrows) of the hypothalamus terminate in the pars nervosa as enlargements called Herring bodies (black arrows). The hormones produced by these neurons, vasopressin and oxytocin, are stored in and released from the Herring bodies into the blood stream for distribution throughout the body. Ade...