Lysosomes in the spleen of the chick embryo. I. Description in the normal spleen.

Abstract

AbstractThe spleen of the 19‐day chick embryo is shown to contain large amounts of hydrolytic enzymes active at acid pH (acid phosphatase, acid deoxyribonuclease, acid ribonuclease, cathepsin, aryl‐sulfatase and β‐glucuronidase), which are associated with subcellular particles that have the properties of lysosomes. (1) The enzymes can be sedimented with subcellular fractions which contain particles approximately the size of mitochondria. (2) The enzymes are associated with a band of particles of greater density than mitochondria in sucrose gradients. (3) The activities of the structure‐linked enzymes are latent. (4) The cytochemically demonstrable activity of acid phosphatase is found in discrete regions of the cytoplasm of the spleen cells.The amount of activity increases with developmental age of the embryonic spleen. This finding is correlated with the increase in detectable acid phosphatase‐containing particles. The most marked period of lysosome production is from the twelfth to the sixteenth day of development.Previous investigations have shown that both major types of phagocytic cells, granulocytes and macrophages, differentiate in the embryo spleen. It is known that in the mammal these cells are rich in lysosome. The production of lysosomes in the spleen is correlated with the differentiation of granulocytes, and with the functional development of the spleen as a reticuloendothelial organ.