FIELD: reproduction biology. SUBSTANCE: method of identifying estrous cycle phase (estrus, diestrus) is based on morphometric evaluation of secretory morphometric activity of mast cells of mesometrial mesentery in laboratory rats. Estrus phase is linked with active degranulation of periascular mast cells which is reflected by appearance of their maximum in-plane values (perimeter, area, length, width). In diestrus phase, these values become minimal. Discordance of morphometric characteristics thus revealed is confirmed by parallel vaginal cytodiagnostics and is indicative of objectivity of method. EFFECT: improved accuracy of identification. 1 tbl
