Scanning electron microscopy of skin window cells of normal subjects.

With critical-point dried specimens, skin window cells of normal subjects showed a wealth of surface detail with no evidence of underlying nucleus or organells. Cells interpreted as neutrophils were characterized by delicate curved surface folds and variable numbers of fine filopodia; macrophages were larger and usually covered with tightly-packed clusters of knob-like microvilli, their periphery showing many filopodia and broader projections. Some macrophage filopodia took origin from the free surface of the cell and extended outwards to be attached to the coverslip for part of their extent, giving a 'fly-leg' appearance. Filopodial communications between cells were also present. With slow-dried preparations, the cells were flattened and a putative nuclear profile was evident. In these preparations quantitative analysis was made of various cell parameters comparing neutrophils and macrophages. The significance of these features has been discussed in relation to the in vivo inflammatory response as revealed by cell contact with a glass surface. The technique might be useful for studying haematogenous cells in certain disease states.