[Hypothalamo-hypophyseal relationship and its role in gonadostimulation in domestic duck].
The connection between the hypothalamus and the pituitary gland results from hormones released from the hypothalamic neurones. The hypothalamus has two . What is the relationship between Hypothalamus and Pituitary Gland? The hypothalamus is connected to the anterior lobe of the pituitary gland. The pituitary gland, also known as the hypophysis, is a roundish organ that lies A key to understanding the endocrine relationship between hypothalamus and.
The Connection between the Pituitary and Hypothalamus?
The image to the right, from the Visible Human Projectshows these anatomical relationships in the Visible Woman click on the image to see a larger, unlabeled image. Careful examination of the pituitary gland reveals that it composed of two distinctive parts: The anterior pituitary or adenohypophysis is a classical gland composed predominantly of cells that secrete protein hormones.
The posterior pituitary or neurohypophysis is not a separate organ, but an extension of the hypothalamus. It is composed largely of the axons of hypothalamic neurons which extend downward as a large bundle behind the anterior pituitary.
It also forms the so-called pituitary stalk, which appears to suspend the anterior gland from the hypothalamus. The image to the right shows a frontal view of a pig pituitary gland and hypothalamus.
The posterior gland can be seen peeking out behind the anterior gland; pass your mouse cursor over the image for labels image courtesy of Dr. The anterior and posterior pituitary have separate embryological origins.
Pituitary gland - Wikipedia
In many mammals, there is also an intermediate lobe pars intermedia between the anterior and posterior pituitary. A key to understanding the endocrine relationship between hypothalamus and anterior pituitary is to appreciate the vascular connections between these organs.
As will be emphasized in later sections, secretion of hormones from the anterior pituitary is under strict control by hypothalamic hormones. In lungfishit is a relatively flat sheet of tissue lying above the anterior pituitary, but in amphibiansreptilesand birdsit becomes increasingly well developed. The intermediate lobe is, in general, not well developed in any species and is entirely absent in birds.
Functional Anatomy of the Hypothalamus and Pituitary Gland
In general, the intermediate lobe tends to be well developed, and may equal the remainder of the anterior pituitary in size. The posterior lobe typically forms a sheet of tissue at the base of the pituitary stalk, and in most cases sends irregular finger-like projection into the tissue of the anterior pituitary, which lies directly beneath it.
The anterior pituitary is typically divided into two regions, a more anterior rostral portion and a posterior proximal portion, but the boundary between the two is often not clearly marked.
In elasmobranchs there is an additional, ventral lobe beneath the anterior pituitary proper. Here, the posterior pituitary is a simple flat sheet of tissue at the base of the brain, and there is no pituitary stalk. Rathke's pouch remains open to the outside, close to the nasal openings. Closely associated with the pouch are three distinct clusters of glandular tissue, corresponding to the intermediate lobe, and the rostral and proximal portions of the anterior pituitary.
These various parts are separated by meningial membranes, suggesting that the pituitary of other vertebrates may have formed from the fusion of a pair of separate, but associated, glands.