Fibrocartilage

As I mentioned in the video, fibrocartilage is interesting because the appearance depends in part on where the fibrocartilage comes from. Although relatively disorganized, it is at its most organized in the annulus fibrosus of the intervertebral disc. Here, it must be particularly good at resisting compression.

The picture above and to the right is a low mag view of an IV disc from a small monkey.
AF = annulus fibrosus NP = nucleus pulposus.
The disc resembles a 'jelly doughnut' where the annulus fibrosus is the doughnut and nucleus pulposus is the jam centre. The force the disc experiences is mainly compression along the axis from top to bottom of the picture.

Microscopically, the fibres of collagen Type I are arranged in layers, with the fibres in adjacent layers oriented at right angles. Chondrocytes are generally found between the layers. This gives the classic 'herringbone' or 'chevron' appearance to the fibrocartilage.

An explanation as to why having the fibres oriented in this way is advantageous in distributing load to reduce compression is shown in the cartoon diagram below.

Elsewhere, fibrocartilage must not only resist compression, but also twisting and shearing (sternoclavicular joints, pubic symphysis). Here the fibrocartilage will appear disorganized, with bundles of fibres interwoven among one another seemingly at random.Although appearing disorganized, the fibrocartilage is organized in such a way so as to maximize strength and this is why dislocations of the pubic symphysis or sternoclavicular joints are relatively rare.