See also ALTERNATIVE METHODS FOR PAIN RELIEF;
ANALGESIC MEDICATIONS; MALDYNIA;SEXUALLY TRANS-
MITTED DISEASE(STD) PREVENTION.
zygote The cell that results when a spermato-
zoon (SPERMcell) penetrates an ovum (egg cell)
during fertilization. Each GAMETE (sperm and
ovum) is a haploid cell; it contains one half the
genetic material necessary to support life. The
zygote is a diploid cell; it contains all the DNAnec-
essary to create a new life. Fertilization typically
takes place in the fallopian tube. The zygote grows
and divides as it makes its way through the fallo-
pian tube to the UTERUS, a journey of about five
days. When it reaches the uterus the zygote
implants into the endometrium, the thick, BLOOD-
rich lining of the uterus. By the time implantation
is complete the zygote has become a two-layered
structure called a blastocyst.
For further discussion of the zygote within the
context of the structures and functions of repro-
duction and sexuality, please see the overview sec-
tion “The Reproductive System.”
See alsoASSISTED REPRODUCTIVE TECHNOLOGY(ART);
CELL STRUCTURE AND FUNCTION; EMBRYO; FALLOPIAN
TUBE; FETUS; OVA.356 The Reproductive System