Foveola


The foveola is located within a region called the macula, a yellowish, cone photo receptor filled portion of the human retina. The foveola is approximately 0.35 mm in diameter and lies in the center of the fovea and contains only cone cells, and a cone-shaped zone of Müller cells. In this region the cone receptors are found to be longer, slimmer and more densely packed than anywhere else in the retina, thus allowing that region to have the potential to have the highest visual acuity in the eye.
The centre of the foveola is sometimes referred to as the umbo.
The anatomy of the foveola was recently reinvestigated.
Serial semithin and ultrathin sections, and focused ion beam tomography were prepared from 32 foveolae from monkeys and humans. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells.
It was discovered that in monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae of humans and monkeys.

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