# What is the hypophysis cerebri?

Gray’s Anatomy (1918) describes the hypophysis cerebri as follows: The hypophysis ( pituitary body ) is a small reddish-gray body, about 1 cm.

## What it means

- The hypophysis ( pituitary body ) is a small reddish-gray body, about 1 cm. in diameter, attached to the end of the infundibulum of the brain and resting in the hypophyseal fossa. The hypophysis consists of an anterior and a posterior lobe, which differ from one another in their mode of development and in their structure . The anterior lobe is the larger and is somewhat kidney-shaped, the concavity being directed backward and embracing the posterior lobe.
- It consists of a pars anterior and a pars intermedia, separated from each other by a narrow cleft, the remnant of the pouch or diverticulum. The pars anterior is extremely vascular and consists of epithelial cells of varying size and shape, arranged in cord-like trabeculæ or alveoli and separated by large, thin-walled bloodvessels.
- The pars intermedia is a thin lamina closely applied to the body and neck of the posterior lobe and extending onto the neighboring parts of the brain; it contains few bloodvessels and consists of finely granular cells between which are small masses of colloid material.
- The pars intermedia in spite of the fact that it arises in common with the pars anterior from the ectoderm of the primitive buccal cavity is often considered as a part of the posterior lobe which arises from the floor of the third ventricle of the brain. Although of nervous origin the posterior lobe contains no nerve cells or fibers.
- It consists of neuroglia cells and fibers and is invaded by columns which grow into it from the pars intermedia; imbedded in it are large quantities of a colloid substance histologically similar to that found in the thyroid gland. In certain of the lower vertebrates, e.g., fishes, nervous structures are present, and the lobe is of large size. From the pars intermedia a substance, no doubt an internal secretion, causes constriction of the bloodvessels with rise of arterial blood-pressure.
- This substance seems to have a stimulating effect on most of the smooth muscles, acting directly upon the muscle causing contraction.

## Sources

- [Gray's Anatomy of the Human Body (1918)](https://www.bartleby.com/lit-hub/anatomy-of-the-human-body/4d-the-hypophysis-cerebri/)

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