The influence of castration and methimazole on deoxyribonucleic acid content of the pituitary and thyroid glands of White Leghorn cockerels.

The pituitary gland of birds is known to increase in weight with castration and decreases with chemical thyroidectomy. Whether these changes are due to alterations in mitotic activity or to cell size changes has been examined by measurement of deoxyribonucleic acid (DNA) and protein content of these glands. The DNA content of the enlarge pituitary of castrated cockerels is the same as that in the pituitary of normal cockerels. The pituitary size increase may be due to an increase in gonadotrope size including any part of the gonadotrope population which may be obtained by recruitment of other basophils. The retardation in pituitary size and DNA content with methimazole treatment is probably due, at least in part, to growth retardation but may also be due, in part, to the conversion of larger basophils to smaller thyrotropes.