Fertilization I, the sequence of events
- Olfactory receptors (the type of receptors found in our nose, which sense smell)
are found on the surface of the egg and sperm. Thermal cues are also present to
help the sperm find the egg.
- Sperm in the epididymis- undergo surface modifications. (addition of glycoprotein
- Seminal vesicles: add 60% of semen volume (fructose for energy and alkaline)
- Prostate gland: adds 30% of semen volume (ions, citric acid, and acid
- The female reproductive tract- near the cervix area the acidity is high. This is an
antibacterial mechanism of the vagina. Sperm do not die out when they reach
this area because they have a short term buffer system.
- When the sperm reach the fallopian tubes, some of them will travel down the
wrong fallopian tube (the one that doesn’t contain an ovulated egg). The sperm
that have the best chemoreceptors are able to choose the correct fallopian tube
to travel into.
- Cilliary bodies in the fallopian tubes help move the egg downwards (they create
a current downwards towards the uterus- sperm have to work against this
current). Some sperm will get trapped in these cilia and die.
- GalTase is a receptor that is placed on the surface of the sperm. This binds
oligosaccharides on the egg coat glycoprotein ZP3.
- Uncapacitated sperm do not have chemotactic ability (ability to detect where the
egg is based on chemoreceptor input)
- The egg is rich in surface proteins, lipids and carbs. The sperm must have the
ability to pass through all of these barriers. (they carry enzymes in their
- Cortical granules: adjacent to membrane of the egg. The