Selective Binding Sites for the Transfer of Ferritin Into Erythroblasts. I. Preliminary

Although both Ross MacCardle and I spent the early part of our lives in West Chester, Penna., our paths did not cross until 1928. It was my privilege to be his student assistant in freshman botany and zoology courses at Temple University from 1928 to 1929. This marked the beginning of a lifelong friendship.-(9/iver fJ>. gones SUMMARY-In studies of rat and human fetal livers, pinocytosis occurred on any part of the plasma membrane of early erythroblasts and it was not more frequent adjacent to a hepatic or Kupffer cell. This cell surface activity was observed both extravascularly and intravascularly. Formation of pinocytotic vesicles was more than just the internalization of parts of the plasma membrane of early erythroblasts. There was more electron scattering at the site where pinocytosis was being induced. Laminae of the unit membrane condensed to form a single electron-opaque membrane. At higher magnifications, even shallow invaginations were composed of 3 layers: an external amorphous layer with ferritin and other granules adherent to the membrane, the condensed plasma membrane, and an internal layer of relatively electron-opaque granules-presumably ribonucleoprotein