biological phase estrous cycle estrous cycle phase http://purl.obolibrary.org/obo/GO_0060206 https://www.wikidata.org/wiki/Q14908139 The progression of physiological phases, occurring in the endometrium during the estrous cycle that recur at regular intervals during the reproductive years. The estrous cycle is an ovulation cycle where the endometrium is resorbed if pregnancy does not occur. estrous cycle phases