Main Idea Details
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Section 36.2 Human Development Before Birth (continued)
Fertilization
and Early
Development
I found this information
on page.Sequence the steps of fertilization of an egg and implantation
of a blastocyst. The steps are written in scrambled order at right.
Write the steps in the correct order in the boxes.370 Human Reproduction and Development
The sperm that survive the
acidic vagina swim through
the vagina into the uterus.One sperm penetrates the egg,
which changes the electrical
charge of the egg’s membrane
so other sperm cannot enter.The zygote moves into the
uterus and becomes a
blastocyst.300 million to 500 million
sperm are released in the
female’s vagina.The nucleus of the sperm and
the nucleus of the egg unite,
forming a zygote.A few hundred sperm make it
into the two oviducts.The zygote moves down the
oviduct and begins to divide by
mitosis.The blastocyst attaches to the
uterine lining.