The utricular macula is located on a horizontal plane, contrary to the saccule which is on a vertical plane. The former is found on the base of the utricle, the second, on the anterior wall of the saccule.
The squamous or simple cuboidal epithelium, which lines the endolymphatic space, grows in height in the oval region of the maculae while at the same time it differentiates into support cells and two types of sensory cells, following a model that is similar to that of the ampullary crests.
The sensory cells are topped by an extracellular gelatinous membrane, called either statoconial or otolithic, which are comprised of crystal particles made of calcium carbonate, statoconia or otoliths.
Like the sensory cells of the cresta, those of the maculae have a kinocilium and stereociliae. Not as long as those of the cresta, the cilia, between seventy or eighty in number, do not plunge directly into the membrane of the statoconiae, but are surrounded by a narrow endolymphatic space. In the centre of each macula is an area called the striola where hair cells are much less numerous, and the majority are type I.
On either side of the utricular striola, in a linear format, the hair cells face each other and are located to the side of their kinocil. On both sides of the saccular striola, in the shape of an “L”, the hair are located to the side their stereociliae.
THE CUPULA
Located on the ampullary crest of the semi-circular canals and houses the ciliary systems in its mass.
It completely blocks the lumina from the membranous canal.