Book - Contributions to Embryology Carnegie Institution No.27

From Embryology

The Development And Function Of Macrophages In The Repair Of Experimental Bone- Wounds In Rats Vitally Stained With Trypan-Blue

By Charles Clifford Macklin, Associate Professor of Anatomy, University of Pittsburgh.


With four plates.

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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Introduction

The vital-slmning route as an ap})roach to the problem of bone-repair came as a natural consequence of the recent work of Shipley and Macklin (1916'-^) on osteogenesis. By subjecting very }^oung, growing animals to trypan-blue, one of the azo-dyes belonging to the benzidine series of colors, these investigators were able to show that the regions of active bone-growth took a more intense stain than the remainder of the bone; and, furthermore, that the heightened coloration was largely referable to the presence in these areas of innumerable phagocytic cells, within whose cytoplasm the dyestuff was stored in multitudinous tinj^ segregations known as "dye-granules."


These phagocytes were identified as the reticulo-endothelial cells of the young bone-marrow. Their reaction to the dyestuffs of the benzidine group is the same as that of the host of cells found throughout the bod}-, which have been extensively studied by different authors, and to wliich various names have been given, such as "pyrrhol-cells" (Goldmann, 1909), "clasmatocytes" (Ranvier, 1899-1900), "resting-wandering cells" (IMaximow, 1906), etc. Recently Evans (1915) has employed Mctschnikoff's term "macrophage" to cover this entire group of phagocytic cells which are united by a uniform functional response to these colloidal dyestuffs, and it is now well recognized that the term "macrophage" is a physiological designation, including within its compass very diverse morphological elements. This similar staining reaction, indeed, is but an expression of the phagocytic potential which these cells hold in common (Evans and Schulemann, 1914) and which mani- fests itself during their every-day existence in the ingestion and storage of certain elements of the surrounding tissue-fluids.

In consideration of the vigorous phagocytic properties attributed to these cells, and also of their being present in large numbers where temporary' bone and cartilage were being absorbed, it seemed evident to Shipley and ^lacklin (1916) that they were a very important factor in active osseous development and that their peculiar role under these circumstances w'as played in connection with the resorption of the provisional cartilage and bone.


Now bone-resorption is an active process in the later stages of bone-repair, for it is well known that the excess of provisional callus which is built up following a bone-injury, such as a fracture, is gradually removed. Since the resorption of this provisional callus is quite similar to that of provisional new bone it was decided to investigate the vitally stained cells in the callus of healing bone-wounds and to compare the findings with those in young, growing bone.


In tlio onrlicr stages of the roparative process following bone-wounds, too, there is a great deal of deliri? to be eliminated, such as injured bone, blood-clot, damaged muscle, and other devitaUzed tissue, and it is plain from the writings of other workers that the potentialities of the macrophages eminently fit them for the performance of tlxis duty. That they play a part in the healing of wounds of soft tissues, such as skin, kidney, and liver, may be inferred from the work of Goldmann (1912), who demonstrated by the aid of vital-dyes that they were increased in tlie regions where repair was proceeding. Indeed, the evidence of numerous investigators jioints to the macrophages being concerned in all inflammatory conditions. Maximow (1902, 1909^), notably, has made a special study of these cells in inflammatory areas, where he finds them increased in number and size, and speaks of them as "i)olyblasts"; and Tschaschin (1913) has recorded similar findings.


The problem of the heahng of wounds of bone, therefore, seemed to offer a particularly favorable field for the application of the vital-staining method, for it was expected that in the earlj^ stages of bone-repair, where damaged soft parts must lie cleared away, as well as in the later stages, where provisional bone has to be eroded, the trypanopliil cells — i. e., the macrophages — in the pursuance of their physiological vocation as phagocytes, would become locally very numerous and would show hypertrophy and intensified phagocj^tic power. These expectations, as will be seen, were realized, and the following pages are devoted to the discussion of the gross and microscopic appearances jiresented in the progressive stages of healing of fractures and trephine wounds in rats in whose tissues the macroi^hages were made visible by the introduction of the dj'estuff (trypan-blue) into the circulating fluids shortly before death.



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Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)


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Cite this page: Hill, M.A. (2019, October 18) Embryology Book - Contributions to Embryology Carnegie Institution No.27. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Contributions_to_Embryology_Carnegie_Institution_No.27

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G