1. A review of the literature on cartilage canals is given. 2. The formation of cartilage canals commences when the cartilage mass exceeds the maximum thickness which can be nourished by diffusion of fluid from the surface. This maximum thickness or the critical size at which canalization would occur, has been worked out in the distal femoral epiphysis at various developmental stages. It varies with the age of the foetus 0.25 mm. at the fourth month and gradually increasing to about 0.6 mm. at full-term. 3. Because of the restricted area of origin of the cartilaginous epiphysis of long bones, the canals seldom found, to be arranged in a radial fashion to the whole epiphysis, but they arranged so as to distribute the blood evenly through the whole mass. 4. (i) The clear, well-formed communicating canals have been seen in the epiphysis of human long bone as early as the fourth month of foetal life. (ii) As development proceeds, some of the communicating canals appear to become obliterated in, the region of proliferating cartilage adjacent to the metaphysis: this obliteration of canals occurs more rapidly after the onset of epiphyseal ossification so that by the time ossification of the epiphysis is complete, no communications between the diaphysis and the epiphysis remain. (iii) It is suggested that probably the primary cause of the formation of the communicating canal is the chemio-taxio influence in the zone of actively growing cartilage in the region adjacent to metaphysis, which directs the ends of the canals arising from the perichondrium near the end of the shaft to bend towards the diaphyseal end. (iii) The probable function of the communicating canals is that they assist in the supply of nutrition to and in the removal of waste products from the cells in the active juxta-metaphyseal cartilage. The almost invariable absence of osteogenic elements in these canals given no support to the hypothesis that they take part in the formation of the centre of epiphyseal ossification. (v) The vascular connective tissue buds which are identical with the communicating canals in the epiphysis of long bone, have boon observed in the cartilaginous sternal end of the clavicle of a human foetus. 5. It is suggested that the cartilage canals grow by a combination of three methods that is by surface accretion, stretching due to interstitial growth and active invasion of the cartilage by the tip of the canal. 6. The cartilage canal connective tissue contents are of perichondrial origin, and are not formed by back differentiation of the cartilage to an embryonic type of connective tissue. 7. In the long bone of the human, the cartilage canals are probably responsible for the formation of the epiphyseal ossification centre.

Low back pain is one of the major health concerns in the US. It affects up to 80% of the population at some time during their lives. It not only causes discomfort to patients and affects their physical ability but also has a huge economic impact on society. Although the cause of low back pain is still poorly understood, it is implicated that degeneration of the intervertebral disc is the primary factor. Currently, researchers are trying to use tissue engineering approaches to develop new treatments capable of removing the degenerated disk and replacing it with a biological substitute. However, to create such a biological substitute, we need to first understand the structure-function relationship of the tissue. Only when we understand the function of the tissue, can we begin creating biological substitutes. While culturing a biological substitute, we also need methods to determine how the substitute responds to its environment. At present, there are many different types of bioreactors developed for cartilaginous tissues. However, there is a lack of a system that can detect the chemical, electrical and mechanical response noninvasively with control feedback in real-time. It is hard to provide the optimal culture environment to the substitute without knowing its response in real-time. The objective of this dissertation is to develop new methods to investigate the transport property, oxygen consumption rate and mechano-electrochemical and mechanical properties of the tissue. Because cells are responsible for the tissue health, it is necessary to understand how they can obtain nutrients under different environments, e.g. under different loading condition. In addition, with the use of a bioreactor with the capability of detecting the real-time response combined with a feedback control system, we can provide the most favorable conditions for tissue or biological substitutes to grow. The new measurement methods developed in this dissertation can contribute to further understanding the function of the tissue. The methods outlined in this dissertation can also provide new tools for future tissue engineering applications. Moreover, the findings in this dissertation can provide information for developing a more comprehensive theoretical model to elucidate the etiology of disc degeneration.