Embryology: Human Reproduction

By: Laura Poleshuk

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Spermatogenesis is the production of sperm, the male reproductive cell, in the testes.

A male begins to carry out spermatogenesis after puberty and occurs throught the rest of their life. The process takes around 72 days total. After the sperm is produced, it is stored in the epidymis. The bulbourethal gland, the seminal vesicles, and the prostate produce seminal fluid which activates the sperm and provides it with sugar for energy. When the sperm is ready to leave, the tube called the vas defrans transport the sperm past the seminal vesicles and the prostate gland and into the urethra. About 100 million to 300 million sperm are released in a single ejaculation.


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The sperm cell carry out meiosis to creat four unique daughter cells. The sperm has many different parts that all the cell to function and fulfill its purpose.The acrosome has a powerful enzymes to break through barriers to get to the ova. The nucleus contains and protect the paternal DNA. The mitochondria in the midpiece provides energy for the sperm to make its journey to reach the egg. The tail, or flagella, propells the sperm and allows it to swim. It only takes one sperm cell to fertilize an ova.


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The process of Oogenesis is of which the ovum, the female gamete, is produced in the ovaries.

Oogenesis begins before birth and ends at menopause, midway through a woman's life. It only produces one fuctioning egg and it also produces polar bodies.The polar bodies release horomones that help regulate the menstrual cycle and early stages of pregnancy. It is better to have only one ova produced because it allows the ova to to contain the majority of the cytoplasm and nutrients. The ova needs all of this so that it can support a developing embryo. Only one ova is released once per month from the ovaries in ovulation. From there the egg travels to the fallopian tubes, then uterus.


external image human-ovum-structure.jpeg
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By the time a female is born, she has her totally supply of ovum, or eggs. A woman is born with three million eggs, but are left with 400,000 by the time she reaches puberty. The ova is the largest cell in the human body because it sustains a baby. It has a nucleus, a cell membrane, and cytoplasm. In addition, is has an extra jelly layer outside. The jelly layer adds extra protection to the ova. The polar bodies are also located in the cell.




Helpful Links

http://www.timesonline.co.uk/tol/life_and_style/health/article418322.ece

the full journey of the sperm

http://biology.clc.uc.edu/courses/bio105/reproduc.htm

more information on male and female reproductive systems

http://www2.hu-berlin.de/sexology/ECE2/html/egg_and_sperm.html

more information on human gametes (click the egg or sperm links on the left side of the page)



Animation

http://www.britannica.com/EBchecked/topic-video/205305/82853/This-animation-shows-how-the-human-egg-is-produced-and

Work Cited!:

Gametogenesis class notes & the incredible journey reading guide (from previous homework)