202 ❯ STEP 4. Review the Knowledge You Need to Score High
The sperm is ready to enter the female reproductive system at this point, but before we observe
the sperm as it does so, we want to take a quick tour of the female reproductive structures.
We begin in the ovary,the site of egg production. Females have two ovaries—one on
either side of the body. The egg leaves the ovary before it has fully matured and enters a
structure called the oviduct.The oviduct is also known as the fallopian tube—you may
be more familiar with that term. Eggs travel through here from the ovary to the uterus.
When fertilized by an incoming sperm in the fallopian tube, after several days’ transit from
the tube to the uterus, the egg usually attaches itself to the inner wall of the uterus, which
is known as the endometrium.The uterus connects to the vaginal opening via a narrowed
portion called the cervix.As we pass through the cervical area, we now find ourselves in
the vagina, and it is here that the sperm enters the female reproductive system.
As the sperm enters, it must survive the different environment that the female body
presents (Figure 16.2). Its task is to find its way to the fallopian tube, where it must meet
the egg and penetrate its outer surface to achieve successful fertilization. The sperm works
its way through the vaginal region, up through the cervix, through the uterus, and into the
fallopian tube. Here, if the timing is appropriate, there will be a willing and waiting egg
that is hoping to meet with a sperm to produce a new diploid zygote. After successful fer-
tilization, the new happy couple moves down to the uterus and builds a nice house in the
endometrium where it will develop into an embryo and remain until it is ready to be born.The Formation of Gametes
In Chapter 9, we discussed cell division and mentioned the process by which gametes
are formed. Remember that the mechanics of gamete formation are different in women
and men.Figure 16.1 The human male reproductive system. (FromBiology,8th ed., by
Sylvia S. Mader, © 1985, 1987, 1990, 1993, 1996, 1998, 2001, 2004
by the McGraw Hill Companies, Inc. Reproduced with permission of
The McGraw-Hill Companies.)