Reproductive System

• Once upon a time, there was a reproductive system. Each month, due to changes in hormones, the uterus invites a thick, soft lining made up of tissue and blood to grow along its walls.
• The lining contained nutrients that would be needed to nourish a growing baby if a pregnancy were to occur.
• Once the lining had grown, it waited for the ovaries to do their job.
• The ovaries contained special reproductive cells, each cell called an egg.
• Each month, one of these cells would reach maturity and be released from the ovary.
• This month, it was the right ovary that released an egg. The left one would have to wait until the next month.
• The fallopian tubes, which wait for the ovaries to release an egg, waved their numerous arms.
• The waving arms grabbed the egg that was just released an gently guided it into one of the tubes.
• After about a day of travel, the egg began to dissolve.
• When the egg had disappeared, the brain sent a message to the lining of the uterus telling it that a fertilized egg wasn't going to arrive, so it could leave the uterus.
• Slowly, the lining passed through the cervix, into the vagina, and out of the body.
• As soon as the lining was gone, the uterus invited a new lining to start to grow. This time around, it would be the ovary and fallopian tube on the left that would do all the work.
• The process would start all over again. This process is called the menstrual cycle.
• Once upon a time, there was a pair of testicles. They were held in a special sac called the scrotum.
• This sac could hold the testicles close to the body to keep them warm or let them hang away from the body to keep them cool.
• Male: The testicles make special reproductive cells called sperm.
• Male: Once the sperm were made, they would wait to be released from the testicles.
• Sometimes, the sperm would wait so long that they dissolved. Other times, they would be released from the testicles, make a journey through the reproductive system and leave the body.
• Male: One day, the sperm will be released from the body. First, the penis became larger and firmer until it stuck out from the body.
• When the penis become larger and firmer, it is called erection.
• The sperm travelled up the vas deferens. Along the way, it mixed with fluid from the prostate gland, and with seminal fluid, which was made in the seminal vesicle.
• Once these fluids mixed, they decided to call themselves semen. Together they travelled from the vas deferens into a tube called the urethra.
• Male: After travelling through the vas deferens and the urethra, the semen was released from the penis in a process called ejaculation. The erection went away and the penis became smaller and softer.
• Once upon a time, there were two important cells, the sperm and the egg.
• The sperm cell was made and stored in a testicle.
• The egg cell was stored in an ovary.
• During sex, the sperm travelled from the testicle through the vas deferens to the urethra out of the end of the penis into the vagina, past the cervix through the uterus, and into the fallopian tube.
• The sperm would meet the egg in the fallopian tube.
• As the sperm travelled through the vas deferens, it mixed with other fluid and was now called semen.
• Ejaculation is when semen leaves the penis.
• For the two cells wo meet, the egg would have to mature and leave the ovary.
• The egg travelled out of the ovary and into the fallopian tube, a process called ovulation.
• The meeting of the two cells happens after sex when a penis enters a vagina. Sperm cells in semen are ejaculated out of the penis and into the vagina.
• Hundreds of millions of sperm cells are ejaculated out of the penis, but only 1,000 make it as far as the fallopian tubes.
• Once the sperm cells found the egg, they started trying to break through the outer lining of the egg.
• One sperm cell broke through the lining and attached to the egg.
• The breaking through and attaching process of the sperm is called fertilization.
• The two cells now became one, called a zygote.
• Once one sperm cell entered the egg, none of the other sperm cells could enter the egg.
• The zygote begins to divide into two identical cells, and those two divide into four, and so on.