A comparative fine structure study on myofibroblasts from a cultured human and an in-situ rat tumor source.

Cultured cells from human embryonal testis (HET 1) and basal-cell (BCE-5) carcinoma and cells from the peripheral region of growing tumors of rat adenocarcinoma (13762NF) were harvested and processed for examination with the electron microscope. Cells from the culture sources were collected from Percoll density fractions of 2-10%, 24% and 35%. The results demonstrate that cells from all sources were morphologically reminiscent of myofibroblasts (Gabbiani et al., 1971). They were elongate, fibroblast-like, appearing cells containing mitochondria, endoplasmic reticulum, Golgi complexes, filaments and microtubules. They also contained filament bundles associated with electron densities typical of myofibroblasts described elsewhere. Furthermore, cells from the 35% Percoll density gradient fraction were characterized by the presence of filament-containing vacuoles whose constituent filaments had a 60-65 A periodicity. It is concluded that cells from all three sources are morphologically similar, and are classifiable as myofibroblasts, and that cells from the 35% Percoll density fraction are also involved in collagen anabolism and/or catabolism.