• It is started from First day of menstrual period to continue till 5th day.
• If the sperm and ovum not fertilized at ampulla of the fallopian tube
• Then the corpus luteum stop produce progesterone hormone which is necessary for maintenance of pregnancy or for intact of endometrium to sustain pregnancy.
• The corpus luteum sinks into corpus albican.
• So the progesterone levels fall.
• Due to fall of progesterone levels the endometrium lining with blood , capillaries and unfertilized egg shed through the vagina.is called menstrual phase.

SECRETORY PHASE