Ultrastructural alterations of the thyroid follicular cells in domestic fowls following neonatal olfactory bulbectomy.

1. In order to investigate if ultrastructural alterations of thyroid follicular cells are induced by removal of the olfactory bulb at hatching, chicks were olfactory bulbectomised within 24 h after hatching and the thyroid follicular cells were examined at 5 months of age by electron microscopy. 2. Olfactory bulbectomised chickens showed a well-developed Golgi area, a highly-developed rough endoplasmic reticulum, many mitochondria and a paucity of secretory granules and lysosomes in thyroid follicular cells. 3. These hypertrophic ultrastructural changes in follicular cells of operated birds indicated that the thyroids glands were stimulated by neonatal olfactory bulbectomy. 4. This finding may suggest an establishment of the olfactory bulbothyroid glandular system during the early days of life in the chicken.