Solid cell nests of the thyroid. An anatomical survey and immunohistochemical study for the presence of thyroglobulin.

A systematic anatomical study of 100 adult human thyroids from autopsies was undertaken for the presence of solid cell nests (SCN). SCN were mainly located in the middle third, with a slight tendency to the upper third, of the lateral thyroid lobes, and placed along a central to paracentral and slightly dorsal longitudinal axis. Immunohistochemical studies for thyroglobulin revealed positive staining in follicular cells connected to SCN and, occasionally, in isolated cells lying within solid clusters from SCN. The anatomical position SCN showed in the present survey is comparable to that shown by the ultimobranchial body (UB) vestiges of human fetuses. The presence of thyroglobulin-positive cells within solid clusters, together with the existence of follicular cells connected to SCN, suggest that SCN may also be a probable source of follicular epithelium as occurs with the UB of some mammals.