Given below is the diagram of a human sperm. Read the information below the diagram and fill in the blanks: 
The two structures shown below are formed in the process of spermatogenesis. Study them carefully and answer the questions that follow.
Menstrual cycle is the monthly series of changes a woman's body goes through while having a possibility of pregnancy. Each month one egg is released by the and this process is called ovulation. If ovulation takes place and the egg isn't fertilized, the lining of the uterus sheds through the vagina. This is a menstrual period.
Menstrual cycle irregularities can have many different causes, including: