The paraventricular nuclei produce the hormone oxytocin, whereas the supraoptic nuclei produce ADH. The posterior pituitary gland does not produce hormones, but rather stores and secretes hormones produced by the hypothalamus. These hormones are stored or released into the blood via the capillary plexus. Neurosecretory cells in the hypothalamus release oxytocin (OT) or ADH into the posterior lobe of the pituitary gland. The cell bodies of these regions rest in the hypothalamus, but their axons descend as the hypothalamicвЂ“hypophyseal tract within the infundibulum, and end in axon terminals that comprise the posterior pituitary (Figure 2).ДЇigure 2. The posterior pituitary is actually an extension of the neurons of the paraventricular and supraoptic nuclei of the hypothalamus. Stimulates melanin formation in melanocytes Stimulates uterine contractions during childbirth Stimulates hormone release by adrenal cortex Stimulates thyroid hormone release from thyroid Promotes milk production from mammary glands The pituitary gland consists of an anterior and posterior lobe, with each lobe secreting different hormones in response to signals from the hypothalamus. It connects to the pituitary gland by the stalk-like infundibulum. The hypothalamus region lies inferior and anterior to the thalamus. The hormones secreted by the posterior and anterior pituitary, and the intermediate zone between the lobes are summarized in TableВ 1.ДЇigure 1. It consists of two lobes that arise from distinct parts of embryonic tissue: the posterior pituitary (neurohypophysis) is neural tissue, whereas the anterior pituitary (also known as the adenohypophysis) is glandular tissue that develops from the primitive digestive tract. The pituitary gland is cradled within the sellaturcica of the sphenoid bone of the skull. In addition, the hypothalamus is anatomically and functionally related to the pituitary gland (or hypophysis), a bean-sized organ suspended from it by a stem called the infundibulum (or pituitary stalk). It has both neural and endocrine functions, producing and secreting many hormones. The hypothalamus is a structure of the diencephalon of the brain located anterior and inferior to the thalamus (Figure 1). In many cases, a stimulus received by the nervous system must pass through the hypothalamusвЂ“pituitary complex to be translated into hormones that can initiate a response. In addition, the hypothalamusвЂ“pituitary complex coordinates the messages of the endocrine and nervous systems. 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. The hypothalamusвЂ“pituitary complex can be thought of as the вЂњcommand centerвЂќ of the endocrine system. 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.Identify the two hormones released from the posterior pituitary, their target cells, and their principal actions.Explain the interrelationships of the anatomy and functions of the hypothalamus and the posterior and anterior lobes of the pituitary gland.By the end of this section, you will be able to:

Pituitary gland hormones