The periosteum. Autoradiographic studies on cellular proliferation and transformation utilizing tritiated thymidine
Tonna, E.A.; Cronkite, E.P.
Clinical Orthopaedics and Related Research 30: 218-233
1963
ISSN/ISBN: 0009-921X PMID: 4172521 Document Number: 5889
This presentation of the wide variety of experiments conducted in our laboratory to unravel some problems in periosteal cell physiology has shown the type and importance of the information which can be obtained through the application of simple autoradiographic procedures. The functional nature and the role of the periosteum in bone growth, development, repair and aging have been expanded as a result of these studies. In addition, skeletal cell studies at the periosteal site have furnished information of importance to the behavior and the potentialities of the skeletal system as a whole, as well as basic data for future studies involving pathologic alterations and the effects of radiation. In the light of the autoradiographic results, the importance of the periosteum appears to stem solely from the osteogenic layer. The periosteum is now seen as a chrondro-osteogenic progenitive pool of cells which contributes to the expansion of the epiphyseal plate and the articular surfaces, as well as to circumferential, appositional growth of the diaphysis. This means that the periosteum is also involved to some degree with longitudinal growth of the diaphysis and the spherical growth of the epiphyseal surfaces. It has also been demonstrated that periosteal cell proliferation is considerably diminished a short time after birth; however, aging does not appear to change the nature of the biologic response to trauma, only the degree of response. More important, many, if not all of the osteogenic cells of the periosteum maintain their capacity to divide and to participate in skeletal repair during aging, even though many morphologic changes occur within these cells. Another interesting feature which has been uncovered autoradiographically is the fact that the periosteal proliferative response to trauma is extensive and not limited initially to the fracture site and is not dependent on trauma to the bone proper or to the periosteum itself. The experiments which have been described in this article have answered some of the problems, but many more remain unanswered. The autoradiographic method employing radioactive compounds to label cells has provided a new departure for attack on old problems which replaces static observations by dynamic data. Because of the limitations of space we have reported only those studies which have been investigated with tritiated thymidine. However, metabolic information is also available through the use of other tritiated compounds, e.g., tritiated amino acids. A considerable body of much-needed information concerning the skeleton will be available in the near future through the use of autoradiographic methods.
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