Mesenchymal activity as a factor in resistance against mouse sarcoma in chick

Abstract

The digestive capacity of a mesenchymal cell in the embryo and of a connective-tissue cell in the adult organism has been recorded many times in the literature.

A mesenchymal embryonic cell, being a very mobile element, will easily detach itself from the common mesenchymal syncytium, and in the presence of a foreign body will ingest it. Under normal conditions, such foreign bodies in the embryo are for the greater part red blood-corpuscles. While the vascular channels in the embryo are undergoing extensive rearrangement, erythrocytes are frequently found free amongst mesenchymal cells and ingested by the latter. Whether or not an erythrocyte undergoing ingestion is still alive, we do not know. It is a highly differentiated cell, in an unfavorable medium while outside the vessels, and with no further power of proliferation.

The ingested blood-cell undergoes within the phagocyte (of mesenchymal origin) a series of chemical changes, some of them demonstrable under the microscope, which transform it into a structureless mass of protein and result in complete digestion. The embryonic mesenchymal cell, therefore, not only is able to synthesize proteins at the expense of amino-acids, but has itself a digestive power. The intra-cellular digestive capacity of a mesenchymal phagocyte may give us a basis for the understanding of other aspects of a similar activity. Thus, chondroclasts, osteoclasts, and clasmatocytes, which are but modified mesenchymal cells, exercise a digestive power, either intracellular or extracellular.

The mesenchymal embryonic cell is capable of digesting its own proteins in the form of dead cells and possibly some living cells which have lost their normal correlations with the tissues of the organism, and it exercises this power from the earliest stages of embryonic development. We know little of its response to foreign proteins and to normal living cells.