Rio and Ria Case

1. Rio and Ria are brand new, fully capacitated sperm waiting happily in a man's epididymis. They are on their journey to find Ma.

Before Rio and Ria could be stored in the epididymis, they were "manufactured" first. This manufacturing occurred in the seminiferous tubules and the sperm goes through three stages before it actually becomes a sperm. These stages are being a spermatogium, then a spermatocyte, and then a spermatid. After this happened, Rio and Ria continued into the rete testes. These are a network of tubes located on the top of the surface of the testis, which the sperm moves out of and works its way to the epididymis. We are now at the current location of Rio and Ria. The epididymis is located on the side and top of the testis and is coiled into a tiny curved area. While Rio and Ria are in the epididymis, they will mature and could have been here for up to six weeks. Their journey continues as they move into the vas deferens. The vas deferens allows Rio and Ria to move out of the scrotum and prostate and into a small place called the ejaculatory duct. Now, that Rio and Ria are about to be ejaculated, the ejaculatory duct opens into the urethra and they are finally ejaculated from the man's penis into the woman's vagina to finish their journey: to find Ma.

During a woman's menstrual cycle, she ovulates which means a matured ovum is released from one of the woman's ovaries. In this case, Ma was released from an ovary. The cervix must anticipate the appearance of sperm by secreting mucus. Once ejaculated, Rio and Ria were two of about 200 million sperm that made it into the woman's vagina and now they must make their way to egg, but face some challenges on the way. About 50% of the sperm that got ejaculated with Rio and Ria, will progressively make its way out of the vagina due to gravity. Also, the vagina is acidic, and because of this the sperm will be eradicated. The other 50% of the sperm, that includes Rio and Ria, made it into the uterus. From the uterus, the sperm must swim to one of the fallopian tubes. A quarter of the original sperm, swam to the wrong fallopian tube. However, Rio and Ria swam to the correct one. They are now one step closer to meeting up with Ma. Now,