Essentials of Anatomy and Physiology

developing follicles begin to deteriorate; these are
called atretic folliclesand have no further purpose.
Under the influence of LH, the ruptured follicle
becomes the corpus luteumand begins to secrete
progesterone as well as estrogen. Hormones produced
in smaller amounts by the corpus luteum are inhibin
and relaxin.

FALLOPIAN TUBES

There are two fallopian tubes(also called uterine
tubes or oviducts); each is about 4 inches (10 cm) long.

The lateral end of a fallopian tube encloses an ovary,

and the medial end opens into the uterus. The end of

the tube that encloses the ovary has fimbriae, fringe-

like projections that create currents in the fluid sur-

rounding the ovary to pull the ovum into the fallopian

tube.

Because the ovum has no means of self-locomotion

(as do sperm), the structure of the fallopian tube

ensures that the ovum will be kept moving toward the

uterus. The smooth muscle layer of the tube contracts

in peristaltic waves that help propel the ovum (or

zygote, as you will see in a moment). The lining

464 The Reproductive Systems

Ovary

Corpus

luteum

Fertilization

of ovum

Fallopian

tube

Fundus

of uterus Ovarian

ligament

Fimbriae

Mature

follicle

Broad

ligament

Round

ligament

Artery

and vein

Body of uterus

Endometrium

Myometrium

Sperm

Cervix of uterus

Vagina

Rugae

Bartholin's gland

Figure 20–6. Female reproductive system shown in anterior view. The ovary at the

left of the illustration has been sectioned to show the developing follicles. The fallopian

tube at the left of the illustration has been sectioned to show fertilization. The uterus

and vagina have been sectioned to show internal structures. Arrows indicate the move-

ment of the ovum toward the uterus and the movement of sperm from the vagina

toward the fallopian tube.

QUESTION:Which layer of the uterine wall is thicker? What tissue is it made of?