Essentials of Anatomy and Physiology

toneum that covers the ovaries. These ligaments help
keep the ovaries in place.
Within an ovary are several hundred thousand pri-
mary follicles, which are present at birth. During a
woman’s childbearing years, only 300 to 400 of these
follicles will produce mature ova. As with sperm pro-
duction in men, the supply of potential gametes far
exceeds what is actually needed, but this helps ensure
the continuation of the human species.

Each primary ovarian follicle contains an oocyte, a

potential ovum or egg cell. Surrounding the oocyte

are the follicle cells, which secrete estrogen. Matura-

tion of a follicle, requiring FSH and estrogen, was

described previously in the section on oogenesis. A

mature follicle may also be called a graafian follicle,

and the hormone LH from the anterior pituitary

gland causes ovulation, that is, rupture of the mature

follicle with release of the ovum. At this time, other

The Reproductive Systems 463

Fallopian tube

Fimbriae

Ovary

Uterus

Sacrum

Cervix

Rectum

Anus

Symphysis pubis

Urinary bladder

Opening of ureter

Clitoris

Urethra

Labium minor

Labium major

Vagina

Bartholin's gland

Figure 20–5. Female reproductive system shown in a midsagittal section through the

pelvic cavity.

QUESTION:Where is the uterus with respect to the urinary bladder, and why is this impor-

tant?