The vertebral cartilaginous endplate of the preadult rhesus monkey (Macaca mulatta). A correlative scanning electron-and light-microscopic study.

The microanatomy of the preadult rhesus monkey (Macaca mulatta) vertebral cartilaginous endplate was investigated with scanning electron microscopy and light microscopy. The plate contains three zones: an outer noncalcified zone adjacent to the intervertebral disc, a middle zone of acellular islands of calcification surrounded by cellular hyaline cartilage, and an inner zone resembling a cartilaginous growth plate. Fibers from the annulus fibrosus pass through an outer zone into the middle zone. Trabecular bone of a developing annular epiphysis is present in the periphery of the plate. Vertical columns of cartilage traverse the nuclear region of the endplate and occasionally surround blood vessels. These columns and their associated blood vessels probably represent notochordal and fetal blood vessel remnants.