On proliferation of the cells of the liver

WITHIN the last few years I have had an opportunity of studying proliferation of the cells of the liver under various conditions, and the present paper contains the results of the observations made.If we exclude the case of new growths we may say that proliferation in the liver, in common with other tissues, is niet with under two chief conditions, namely, ( a ) in repair following breach of continuity of structure, and ( b ) in compensatory hypertrophy and hyperplasia.The distinction between these two conditions is an important one, both as regards the mechanism by which the proliferation is brought about and as regards the structural changes which follow.Breach of continuity means disturbance of the normal equilibrium or tissue tension, and is followed by proliferation of all the cells whose normal relationships are interfered with; the result is that there is a growth of connective tissue elements in addition to proliferation of the more specialised cells, and the former exceeds the latter both in rapidity and in extent.Thus the epithelial elements are overgrown, as it were, by young connective tissue, and as the latter contracts the former undergo atrophic change rather than full development.It follows that under these circumstances, while there may be a considerable amount of epithelial proliferation, the amount of efficient repair may be comparatively slight.In compensatory hyperplasia the stimulus to proliferation apparently comes from increased metabolism, the result of abnormal functional activity ; it may be considered, as Weigert puts it, to be due to molecular damage (Xclziidigung) in the widest sense.It is well seen in the surviving liver tissue when a considerable proportion of the liver has been destroyed by disease or artificially removed.I n this case the liver cells alone are affected, and thus a proliferation of them occurs without m y participation on the part of the connective [