Pituitary cell

The anterior pituitary, also called the adenohypophysis, is not made of a single kind of cell. To look at it under the microscope you have to stain it, and that is where the surprise shows up: the cells do not take up the color the same way. That detail, which sounds like something out of a dye shop, is the classic way of sorting them.

The ones that stain red or orange are called acidophils, and they usually hold polypeptide hormones, which are chains of amino acids: they are the somatotrophs and the lactotrophs. The ones that take on a bluish or purple color are the basophils, and the basophils that release glycoprotein hormones, which have sugar attached, are the thyrotrophs, the gonadotrophs and the corticotrophs. Then there are the ones that barely take up any color at all, the chromophobes, and there is a very specific reason for that: they have little or no hormone content. Many of them may have been acidophils or basophils that have already released their granules, like a jar that has been emptied. The stain works like a photographic developer: it colors the cell that is still holding something, while the one that has already let it go stays pale.