Histological features of endplates of the mammalian spine: from mice to men.

STUDY

DESIGN

Histological features of the intervertebral disc (IVD)-endplate interface were analyzed.

OBJECTIVE

To define cartilaginous and bony vertebral endplate in commonly used laboratory animals and compare with that of the humans.

SUMMARY OF BACKGROUND DATA: Endplates are crucial for the IVD nutrient supply: the IVDs have limited blood supply; most nutrients diffuse through endplates to nourish the discs. Various animal models of IVD and endplate degeneration have been used to study the etiology and treatments of spinal disorders. However, because humans are biped, the spine mechanics differ significantly from other mammals. Translation of animal research findings requires a characterization and comparison of the vertebral endplate in the respective species. In this study, we compared the endplate structure of laboratory animal species at the age range commonly used for modeling spine degeneration with that of an adult human.

METHODS

Mouse, rat, rabbit, goat, and human IVDs and the adjacent vertebral bodies were isolated from the lower lumbar spine. Tissues were stained with Alcian Blue, counterstained with hematoxylin and eosin.

RESULTS

Structure of the vertebral endplate varied significantly between the adult animal species and that of the humans. Growth plates persisted in all adult animals studied, whereas the growth plate is absent in the adult humans. In the mice and rats, the cartilaginous endplates are in continuation with the growth plates, with only a small bony center. Rabbits and goats have a bony layer between cartilaginous endplate and the growth plate. The human endplate consist of a cartilaginous layer and the bony endplate.

CONCLUSION

Significant differences exist in histological features of the endplate across animal species and that of the humans. Consideration should be given when animal models are used to study IVD degeneration and surgical treatments.

LEVEL OF EVIDENCE: 5.