<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>The monthly cycle of hormonal changes from the beginning of one menstrual period to the beginning of the next.</n0:def-definition><n0:def-source>NCI-GLOSS</n0:def-source></n0:ComplexDefinition>
<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>The Menstrual Cycle involves regularly recurring hormonal changes and physiologic endometrial changes during the reproductive period in human females, and some primates, and culminates in partial sloughing of the endometrium (menstruation) in the absence of fertilization. For most women, one cycle takes 28 days. (NCI)</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>