Oto Cartoon, LUT, Polarized

A 100-micron section from the femur (thigh bone), of Otolemur crassicaudatus, a bushbaby. The animal was about 1 month old when it died. Bushbabies, small primates native to Africa, are often extraordinary leapers.

Top: Circularly polarized light was used to highlight differences in the orientation of the collagen fibers present in the bone, as represented by different shades of gray. The red line indicates the axis along which the bone is strongest when bent.

Middle: Colorization in Adobe Photoshop makes the differences in collagen fiber orientation more obvious to the human eye and brain.

Bottom: Different kinds of bone tissue were identified and assigned colors.

Tissue types provide information about the rate at which the bone is being deposited. In this juvenile we see mostly fast-growing bone in orange, as is usually the case for very young mammals. The patterns of collagen fiber orientation, as well as the red axis, reflect the forces the bones are subjected to during life, which vary depending on the way members of a species move. Examination of juveniles as well as adults can provide information about the growth pattern of a species, and the changes in behavior that occur with age (e.g. baby humans locomote by crawling, while adult humans walk).

Original width 3.5 mm