The menstrual cycle

• The reproductive cycle in females is called the menstrual/estrus cycle
• It has an average of 28 days
• It varies from individual to individual but it follows a set pattern
• The cycle is regulated by hormones produced by the pituitary gland and  ovaries
• The cycle can be tracked using various charts and diagrams

Simplified menstrual cycle chart. Image credit mindupdate.org

• Menstruation occurs from days 1-5
• From days 5 to 10 the uterus lining starts to thicken
• Ovulation occurs midway within the cycle usually from days 10 to 14
• During this time the ovum (egg) is released.
• It is the most fertile period of the cycle
• If copulation/sexual intercourse takes place fertilization can take place
• On Days 14 to 21 the uterus lining remains intact and ready to receive a zygote
• That is if fertilization occur
• On days 22 to 28 the uterus walls continue to thicken and may break at the end of this period
• On days 1 to 5 the uterus lining breaks down if fertilisation has not taken place
• The blood and lining are expelled from the body
• This process is known as menstruation

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