Tubular structures found in tissues and cultures. A. Pre-existence of tubular structures in six tissue types from fresh prepared three-month-old female calf and in frozen prostate tissues from mice. Straw cells typically possess several filament branches that connect to each other. Large quantities of straw cells were seen in liver, lung and prostate tissues followed by skin, with the smallest quantities in brain and heart tissues. B. Dehydration produced straw cells from five types of mammalian cells in cultures. C. SEM micrographs of the tubular network at 50 and 100 μm scale. Multiple straw cells connect to each other; two incoming filaments with growth tips have dark contrast, transformed cell resides inside the tube. D. TEM micrograph of the cross-sections of transformed straw cells. First graph shows multiple straw cells at various diameters, second graph shows a zoom-in image of the cross-section of a tube, tubular wall has a thickness 220 nm. Last graph is the cross-section of longitudinal view of filaments with diameter 1 μm, the thickness of filamentous wall is 120 nm.