is covered by a cap called an acrosome, which contains enzymes required to
penetrate the ovum or egg. The production of ova, female gametes, begins
in the ovaries by a process called oogenesis (Figure 7.36). Primordial germ
cells in the outer germinal epithelium divide by mitosis to form a diploid
primary oocyte that becomes surrounded by follicle cells to produce primary
follicles. These migrate into the center of the ovary. As many as two million
primary follicles are present at birth and remain dormant until puberty.
Approximately 400 primary follicles mature over the lifetime of a female until
follicle development ceases at the menopause. The primary follicle matures
to form a secondary follicle. During this development, the primary oocyte
divides by meiosis but this is arrested and forms a haploid secondary oocyte,
which is the precursor of the ovum, and a small polar body. In an adult
fertile female, the nucleus of a secondary oocyte begins the second meiotic
division at each monthly ovulation but progresses only to metaphase, when
REPRODUCTIVE HORMONESCZhhVg6]bZY!BVjgZZc9Vlhdc!8]g^hHb^i]:YLddY &-.
OviductOvary
Uterus
BladderUrethraClitorisLabium minoraLabium majoraVaginal orificeAnusVaginaCervixFimbriaeB)
Figure 7.34 Overviews of the (A) male and
(B) female reproductive systems.Erectile tissueProstate
glandBulbourethral
glandAnusEpididymis
TestisScrotumBladderVas deferensUrethraPenisGlans penisForeskinSeminal
vesicleEjaculatory
ductA)