"Lens mitochondria" in the retinal cones of the tree-shrew Tupaia belangeri.
In all mammals, the mitochondria of the cones of the retina are concentrated in the inner segment. Uniquely in tree-shrews (Tupaia, Scandentia, Mammalia), a "megamitochondrion" exhibiting highly specialized systems of densely packed cristae and a very electron dense matrix, is located apically in the inner segment. The ellipsoid is a solid body containing several megamitochondria and, towards its base, a large number of smaller mitochondria. The refractive index of isolated, but not oriented, inner segments of Tupaia belangeri is higher (XA = 1.405) than in any other mammal studied so far. The consistent geometrical pattern of the multilamellar crista-matrix systems, oriented longitudinally towards the outer segment, suggests an additional optical function of the megamitochondria.
Knabe
W
W
Anatomisches Institut der Georg-August-Universität, Göttingen, Germany.
Skatchkov
S
S
Kuhn
H J
HJ
D000818:Animals; D008854:Microscopy, Electron; D008928:Mitochondria; D012031:Refractometry; D017949:Retinal Cone Photoreceptor Cells / Q000737:chemistry / Q000648:ultrastructure*; D014417:Tupaia / Q000033:anatomy & histology*