A STUDY OF THE NERVES OF THE THYROID GLAND AND THEIR RELATIONSHIP TO GLANDULAR FUNCTION

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Abstract
The nerves to the thyroid were studied in guinea pigs by intra-aortic injn. of 250-400 ml. of a soln. of methylene blue (0.1 to 0.01 g.) in 7.25 g. NaCl, 2.0 g. glucose; Na acetate 0.3 g.; resorcinol, 0.3 g.; MgCl2 1.25 g.; H2O to 1000 ml., buffered with PO4 to pH 6.1-6.3. The soln. was heated to 50[degree]C before adding dye, and was injd. at 37[degree]C over 5-8 min. The right cardiac ventricle was opened to permit fluid to escape. Nerve fibers found included (1) a perivascular plexus, (2) a perifollicular plexus, (3) large partially myelinated nerve fibers. Vagotomy did not affect the nerve supply; however, sympathectomy was followed by disappearance of many of the nerve fibers. Severing the lower cervical spinal cord did not affect nerves or reduce responsiveness of follicles to thyrotropin. Epinephrine (0.1-0.25 mg. twice daily) did not affect follicle cell height; ergotamine 1-2 mg. twice daily reduced cell height, and partially blocked response to thyrotropin or to cold environment. As judged by thyroid cell height, function is independent of innervation.