Development of The Pituitary Gland

Source

1. The ectoderm of the stomodeum. A stomodeum, also called stomatodeum or stomatodaeum, is a depression between the brain and the pericardium in an embryo and is the precursor of the mouth and the anterior lobe of the pituitary gland.
2.Neuroectoderm of the diencephalon.

Site-roof of stomodeum and floor of diencephalon.

Sequence

By the third week, the roof of stomodeum presents an up growth - Hypophyseal diverticulum(Rathke's pouch) which elongates and is constricted at its attachment to the oral epithelium.

The stalk of Hypophyseal diverticulum passes in between chondrification centers of the developing basisphenoid and presphenoid bones.

In the 6th week, it's connection with the oral cavity degenerates. Cells of the anterior wall of Hypophyseal diverticulum proliferate to give rise to pars distalis, and an extension; pars tuberalis around the infundibular stem.

Cells in the posterior wall of Hypophyseal diverticulum don't proliferate but give rise to a thin pars intermedia.

The neurohypophysis (posterior pituitary) develops as a down growth of the neuroectoderm of diencephalon forming a neurohypophyseal diverticulum.

The infundibulum of neurohypophyseal diverticulum gives rise to the median eminence, infundibular stem and pars nervosa.

Neuroepithelial cells then proliferate and differentiate to form pituicytes. Nerve fibers grow into pars nervosa.

The neurohypophyseal diverticulum comes into contact with Hypophyseal diverticulum to Form the pituitary gland.

Anomalies

1. Pharyngeal hypophysis-persistence of a remnant of the stalk of Hypophyseal diverticulum in the roof of the oropharynx.

2. Craniopharyngioma- tumors arising in the pharynx or basisphenoid from remnants of the stalk of Hypophyseal diverticulum.