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Embryologic Development of the Pituitary Gland

Embryologic Development of the Pituitary Gland

Author: Aaron Mullally
Description:

- know the term diencephalon

- know that the posterior pituitary is called the nuerohypophysis

- know the origin of the neurohypophysis

- know that the neurohypophysis is directly connected to the CNS (hypothalamus)

- know that the anterior pituitary is called the adenohypophysis

- know the origin of the adenohypophysis and how it got to the brain

- know that the adenohypophysis is not directly connected to the central nervous system

 

This packet covers the embryologic development of the anterior and posterior lobes of the pituitary gland

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Tutorial

Overview

It is important that you understand the origins of the pituitary gland because each lobe came from different locations. As a result they are both controlled very differentlly by the hypothalamus. This process begins and finishes very earlly on in embryologic development.

The posterior pituitary is a little easier to explain. From here on out you should refer to the posterior pituitary as the neurohypophysis and here is why. The neurohypophysis is a down growth of the diencephalon (hypothalamus) itself. So this part of the pituitary gland originated from the central nervous system itself. The diencephalon protrudes downward and slightly anteriorally while this process takes place.

At the same time the anterior lob is developing but very differently. *This originates from the upper mucous membranes of the pharynx called the buccopharyngeal membrane. While this is happening the telencephalon of the brain and sphenoid bone are also developing. As the telencephalon of the brain and sphenoid develop the head starts to tilt forward toward. As the head tilts forward the buccopharyngeal membrane starts to fold inward on itself and create an invagination called Rathke's pouch; Rathke's pouch is the beginning of the adenohypophysis. Once the pouch forms surrounding epithelial cells start to form and proliferate into the tissue that will eventually become the adenohypophysis. Then this pouch of cells will be pushed upward through the developing sphenoid bone and into the sella turcica where it meets up with the neurohypophysis. What's left of Rathke's pouch fuses with the infundibulum (stalk) of the pituitary gland and forms the pars intermedia, thus joining the two lobes and forming the gland itself. The gland is not at its full size and strength at birth and enlarges throughout life as it becomes more active and the head itself continues to grow to its full potential.

*Standring, Susan. Gray's Anatomy: The Anatomical Basis of Clinical Practice. London, England: Churchill Livingstone. Print

Source: Self made

Embryologic Development of the Pituitary Gland

This video covers the origins of the anterior and posterior pituitary gland

Source: Self made

Image

Here is the image from the video

Source: Self made