Studies on cell surface conformation following injury

A case of mammary Paget's disease without an underlying carcinoma: microscopic analysis of the DNA content in Paget cells

A 72-year-old woman had a 7-year history of a scaly red area on the right breast which had enlarged asymptomatically. A biopsy of the nipple was taken, and, following the finding of Paget's disease, a modified radical mastectomy was carried out. On histological examination of the entire breast specimen by serial sections, no evidence of an intraductal adenocarcinoma was found. Fractionation of Paget cells was performed from the epidermis. Stripped skin was treated with EDTA and trypsin, and epidermal cell suspensions were obtained. They were layered onto discontinuous Percoll gradients and centrifuged. Paget cells fell into three fractions with densities of 1.041, 1.058, and 1.078. Electronmicroscopically, the purity of fractionated cells obtained by this method ranged from 55 to 74% with viabilities of from 70 to 90%. Microscopic analysis of the DNA content in these cells was performed. The DNA histogram was close to the normal ploidy. This may explain why the mammary Paget's disease lesions in this case enlarged rather slowly.

Analysis of structural changes during hypotonic swelling in Ehrlich ascites tumor cells

Studies were undertaken to quantify structural changes associated with swelling of Ehrlich ascites tumor cells in hypotonic medium. Cells transferred from isotonic (294 mosmol/kg H2O) to hypotonic (98 mosmol/kg H2O) medium swelled rapidly. Subsequently, approximately 40% of the water initially gained was lost, a phenomenon referred to as volume-regulatory decrease (VRD). During the initial rapid cell swelling, blister-like protrusions or blebs were formed on the cell surface. These blebs were examined by routine light microscopy, differential interference-contrast (DIC) microscopy, and scanning and transmission electron microscopy. Microscopic observations and the distribution of ATPase antibodies indicated that the blebs were formed from plasma membrane. During VRD, the blebs coalesced to form a smooth but expanded membrane surface that appeared to be separated from the original cytoplasm by a layer of less dense ground substance. Computer-assisted morphometry from digitized DIC images of the initial swelling phase indicated that all of the volume gained was sequestered in the blebs. We suggest that bleb formation may allow increases in cell volume without disruption of cytoplasmic organization and may be a protective response to a variety of stressful stimuli. The subsequent VRD is accompanied by reduction of this expanded compartment.