Histology of the endolymphatic sac of the rat ear and its relationship to surrounding blood vessels: the "endolymphatic glomerulus".

Histologic and histochemical studies of the endolymphatic sac of full-term rat fetuses were undertaken to clarify the anatomy of the endolymphatic sac, and the mechanism of endolymph circulation and regulation. Hitherto undescribed structure enveloping the sac with blood vessels extending from the sigmoid sinus resembling the kidney glomerulus was seen. This endolymphatic "glomerulus" is believed to provide a means of active exchange of water and electrolytes between blood vessels and the endolymphatic sac.