Eleven adult White Leghorn cockerels, 6 to 9 months of age, were thyroidectomized and sacrificed 6 to 93 days after operation. Two capons and 10 normal cockerels of the same age were also used as controls.
Anterior pituitaries of the sacrificed birds were weighed, and fixed in a formol-sublimate (1:9) solution and stained after GOLDBERG-CHAIKOFF method ('52), HEIDENHAIN'S azan technique and GOMORI'S aldehyde-fuchsin. For the purpose of cytochemical studies, the PAS method, RENNELS'S acid hematein test, FEULGEN'S reaction, ribonuclease test and metachromatic staining by basic dyes were also used.
The results obtained are summarized as follows:
(1) Anterior pituitaries of the thyroidectomized cockerels were markedly hypertrophied. The thyroidectomy cells (T cells) of the glands were observed within the confines of the cephalic lobe. In the capons, however, enlarged basophils were present throughout the cephalic and caudal lobes.
(2) T cells develop directly from some of the cephalic basophils and are morphologically divided into two forms. The one is characterized by its large, clear nucleus surrounded by the cytoplasm containing fine basophilic granules, while the other is distinguished by the cytoplasm containing large hyaline vacuoles. Both types of the T cells are extremely large in size and round, oval and polygonal in forma. Their cytoplasm contains RNA-and PAS-positive granules, but their large vacuoles contain only PAS-positive substance. T cells are considered, from all points of view, to be secretory cells, and there is no indication of de-generative changes.
(3) It is considered that there are two functionally distinct types of the basophils in the anterior pituitary of the fowls. One existing exclusively in he cephalic lobe has developed to T cells due to thyroidectomy, and the other located throughout the cephalic and caudal lobes has been enlarged after castration. The former type is considered to be responsible for the secretion of thyrotrophic hormone, while the latter is concerned with the production of follicle-stimulating hormone.
(4) After thyroidectomy the degranulation of the acidophils of the caudal lobe has been observed with a marked decrease in number, but such decrease was a little in capons.
V cells markedly degenerate indicating picnosis due to thyroidectomy, but remain normal in case of castration. In the thyroidectomized or castrated birds, it is probable that degenerative changes in acidophils and V cells are due to changes in the physiological condition of the pituitary caused by the removal of the thyroids or testes. Therefore, acidophils and V cells are considered to be not responsible for the secretion of follicle-stimulating or thyrotrophic hormones.
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