The high resolution (~350 nm) transmission digital microscopy (TDM) with increased speed is promising tool for in vivo image flow cytometry to real time identification of flowing cells in microlymphatics of rat mesentery without any contrast agents. The main mesenteric microstructures (lymph-vessel diameter, valve geometry, cells, etc.) and their dynamics (wall motion, valve function, cell velocity, etc.) were monitored with TDM. Depending on structure size, different magnifications were used to images of relatively large the whole lymphangion (x4 - x10) as well as to image single cells (x40 - x100) in lymph and blood flow including estimation of their shape, size and aggregation types. Different potential applications of the TDM in vivo are discussed including visualization of circulating of cells in lymph flow, study the kinetics of leukocytes and rare erythrocytes, as well as image absorbing nonfluorescent mesentery structures with high sensitivity and resolution.