Fundamentals of Anatomy and Physiology

470

male prostate gland and they secrete mucus. On both sides
of the vaginal orifice are the openings of two small glands
called the greater vestibular or Bartholin’s glands.
These glands are homologous to the male’s Cowper’s
glands and also secrete mucus. The mucus secreted by
these vestibular glands lubricates the distal end of the
vagina during sexual intercourse.

The Perineum

The perineum (pair-ih-NEE-um) is a diamond-shaped
area at the inferior end of the trunk between the buttocks
and thighs of both males and females (see Figure 19-10). It
is divided into an anterior urogenital triangle that con-tains
the external genitalia and a posterior anal triangle that
contains the anus.

The Anatomy and Function

of The Mammary Glands

Mammary glands are present in both males and females
but normally function only in females. Their function is to
produce milk to nourish the newborn baby. Estrogen causes
the mammary glands to increase in size during

Chapter 19

puberty. These glands are modified sweat glands and are

located in a round skin-covered area called the breast,

anterior to the pectoralis major muscle of the thorax.

Each mammary gland consists of 15 to 20 lobes or

compartments separated by adipose tissue. It is the amount

of adipose tissue present in the breast that de-termines the

size of the breast (Figure 19-11). In each lobe are several

smaller compartments known as lob-ules, which contain the

milk-secreting cells called alve-oli (al-VEE-oh-lye).

These alveolar glands are arranged in grapelike clusters.

They convey the milk into a series of secondary tubules.

From here the milk passes into the mammary ducts. As the

mammary ducts approach the nipple, expanded sinuses

called ampullae (am-PULL-ee) or lactiferous sinuses

(lak-TIF-er-us SIGH-nuh-sez) are found where milk may

be stored. These ampullae continue as lactiferous ducts

that terminate in the nipple (NIP-l).

The circular pigmented area of skin surrounding the

nipple is called the areola (ah-REE-oh-lah). It looks and

feels rough because it contains modified seba-ceous glands.

The function of the mammary glands is to secrete and eject

milk, a process known as lactation (lak-TAY-shun).

(A)

Figure 19- 11

Skin (cut)^

Pectoralis

major muscle^

Adipose tissue^

Pectoralis minor muscle^

Lobe^

Lactiferous duct

Opening of

lactiferous duct^

Lactiferous

sinus

Nipple^

Areola

(^) ®
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The mammary glands of a lactating breast. (A) Anterior view and (B) sagittal view.
Ribs
Intercostal
muscles
(^) ®
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