TBE object of this paper is to summarize the present state of knowledge concerning the conditions which give rise to hyalinization of basophil cells and to the formation of basophil cell adenomata in the rat pituitary. The hyalinization and basophil adenomata which are found in the human pituitary in cases of the Cushing syndrome will be discussed in the light of the implications of the observations which have been made in the rat.Three types of basophil cell in the rat.-In the pars distalis of the rat pituitary there are three types of glycoprotein-containing cell, each type containing a specific glycoprotein in the form of cytoplasmic granules which are considered to be the storage form of one or other of the three glycoprotein hormones-thyrotrophin, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The names "thyrotrophs", "FSH cells", and "LH cells" have been given to these specific cell types, each of which is considered to be concerned exclusively with the secretion of its appropriate hormone (Purves andGriesbach, 1951, 1954). Since the glycoprotein granules of all three types in the rat pituitary stain blue with about the same intensity by trichrome staining methods, they were, in the period before their diversity was recognized, referred to collectively as "the basophil cells".Hyalinization in basophil cells.-In certain mammalian species, including the rat, rabbit, dog and opossum, the occurrence of hyalinization is observed in basophils during states of high secretory activity such as occur particularly after castration or thyroidectomy.Such changes cannot be regarded as being primarily degenerative since they also occur under normal physiological conditions as, for example, in the opossum (Didelphys virginiana) at the time of onset of gonad maturation (Wheeler, 1943).-Electron-micrograph studies.-The electron-micrograph studies of Farquhar and Rinehart (1954a, b) on the rat pituitary show that the basophil cells contain small ovoid vesicles. It is in these vesicles that hyaline accumulation primarily occurs. The large ,hyaline-filled vesicles which are observed in the rat basophils in the later stages of hyalinization are formed by a secondary coalescence of these small vesicles to form large spaces.Hyalinization after thyroidectomy.-Hyalinization occurring in the rat pituitary after thyroidectomy affects only the thyrotrophs. These cells undergo almost complete degranulation in the first forty-eight hours after thyroidectomy, and thereafter enlarge rapidly. Hyalinization is observable as early as six days after thyroidectomy and takes the form of a large number of small hyaline-containing vesicles which subsequently undergo distension and coalescence until three or four large, irregular, thin-walled, hyaline-filled spaces result (Purves and Griesbach, 1956a). Hyalinization of thyrotrophs after exposure of rats to cold.-In rats exposed to a temperature of 4-C. for fourteen days, a small proportion of the thyrotrophs show an annular zone of small hyaline-filled vesicles with retention of ...

SummaryThe administration of desiccated thyroid inhibited the uptake, but not the release, of I131 (in five millicurie doses) by the metastases of a thyroid adenocarcinoma.The desiccated thyroid was apparently responsible for a marked and sustained reduction in the size of the pulmonary and subcutaneous metastases.It is suggested that in cases of thyroid carcinoma it may be better to try treatment with desiccated thyroid before I131 therapy, rather than after it.