THE PITUITARY

In the human skull, the pituitary is a lump of tissue about the size of a pea lying at the base of the brain, a short distance behind the root of the nose.  It is of a grayish-yellow color, unpretentious and insignificant enough in appearance, and so long neglected by the scientists who boast their immunity to the glamor of the spectacular.  Guesses at its nature date back to Aristotle.

Like most of its colleagues among the glands of internal secretion, it is really two glands in one, two glands with but a single name.  At least it consists of two different parts, distinct in their origin, history, function and secretions, but juxtaposed and fused into what is apparently a homogeneous entity.  They are conveniently spoken of as the anterior gland and the posterior gland.

In the embryo, the anterior gland is derived by a proliferation of cells from the mouth area.  The posterior gland represents an outgrowth of the oldest part of the nervous system.  When it is traced back along the tree of the vertebrate species, it is found to be present in all of them.  An ancient invention, its precursor has been identified in worms and molluscs and even among the starfish.  “The pituitary is practically the same, from myxine to man.”  A trusted veteran, therefore, among the internal secretory organs, its importance can be surmised.

To understand the story of the pituitary, variously acquired bits of information concerning it have been assembled and fitted together like the fragments of a picture puzzle, as Cushing has so well put it.  Here and there pieces stick out, obviously out of place.  The relations of some of them to one another or to the whole design are not at all clear.  Parts appear to have been irrevocably lost, or not yet to have turned up.  Chance bystanders will select odd figures and articulate them into a new harmony.  Yet out of the jumble of fragments, a fairly respectable insight has been gained in less than a half century.

The pituitary is cradled in a niche at the base of the skull which, because of its form, is known as the Sella Turcica or Turkish saddle.  So situated, an operative approach to it is overwhelmingly difficult.  On the other hand, X-ray studies are favored.  “Nature’s darling treasure” it might be called, since there has been provided a skull within the skull to shelter it.

Under the most highly magnifying lenses of the microscope, three kinds of cells have been distinguished.  The anterior gland is a collection of solid columns of cells, surrounded by blood spaces into which their secretion is undoubtedly directly poured.  A gelatinous material, presumed to be the internal secretion of the gland, has, in fact, been observed emerging from the cells into the blood spaces.  The posterior lobe, or gland, consists of secreting cells producing a glassy substance which finds its way into the spinal fluid that bathes the nervous system.  The spinal fluid itself is a secretion of another gland at the base of the brain, the choroid.  Nerves and internal secretion are associated here with a closeness symbolic of their general relations.