4. Answer is colloid. follicular cells, C cells are cells in the thyroid. Calcitonin and parathyroid hormone are synthesised by the thyroid. 5. Answer T3 and T4. the hypothalamus senses the levels of the two homones and when their circulation is low releases the thyrotropic releasing hormone which stimulates the pituitary to release TSH. 6. The androgen is the male sex hormone produced in the testes. 7. ACTH is a peptide hormone Solution 4. Answer is colloid. follicular cells, C cells are cells in the thyroid. Calcitonin and parathyroid hormone are synthesised by the thyroid. 5. Answer T3 and T4. the hypothalamus senses the levels of the two homones and when their circulation is low releases the thyrotropic releasing hormone which stimulates the pituitary to release TSH. 6. The androgen is the male sex hormone produced in the testes. 7. ACTH is a peptide hormone.