Peculiarities of the thyroid gland structure (with special reference to the presence of ganglion cells).

We have performed a study on the comparative structure of the thyroid gland in several species of mammals (rat, cat, dog, lamb, pig, cow, and man). We have described the structural differences among them, paying special attention to the distribution of connective tissue, the intrafollicular and parafollicular cells. In the thyroid gland, we can confirm the existence of nerve cells, either isolated or forming vegetative ganglions in the interfollicular spaces, in some of the species studied, especially in the rat and the dog.