The Female Reproduction System
Identify the components of the female reproductive tract (ovary, oviduct, uterus,
vagina and breast) and recognize structural changes which occur during the menstrual
cycle or pregnancy
The ovaries (slide #79) are paired gametogenic and endocrine
glands. Each ovary consists of a cortex containing follicles with
oocytes and a medulla with prominent blood and lymph vessels. Examine
both odd and even slides of the ovary. The flattened or cuboidal germinal
epithelium (mesothelium) on the surface of the ovary is easily torn loose
and is often missing (best seen on #79 even). Underlying the germinal
epithelium is the tunica albuginea which consists of a thin layer of dense,
circular connective tissue with fibers running roughly parallel to the
surface. The deeper cortical area contains the follicles. The cortical
stroma is highly cellular, and the elongated stromal cells are arranged
in wavy patterns or whorls.
Examine the blood vessels in the medulla. The lymphatic vessels are
particularly prominent on slide #79 odd, and can be distinguished on
the basis of their fluid content (few leukocytes and no RBCs), their thin walls,
and the presence of valves projecting into the lumen. Compare their walls with
those of veins which are also present and contain RBCs.
Follicles of all sizes are found in the ovary of a reproductively active woman.
Slide #79 odd is the ovary from an older woman and contains some primordial
follicles, a few secondary (vesicular) follicles and many late atretic follicles.
The monkey ovary on slide #79 even contains follicles at various stages
of development. It may contain several primary (growing) follicles with two
or more oocytes. These are common in monkey ovary but very rare in human ovary.
Many of the follicles are undergoing atresia. You may have to use atretic follicles
for examples of different stages of follicular development. Using slides
#79 odd and even find:
1. Primordial follicles
The small primordial follicles measure about 30 Ám ( the diameter of
four to five RBCs) and have a single flattened layer of follicular cells
around the oocyte.
2. Primary follicles (growing solid follicles)
When follicle growth begins, the flat follicular cells become cuboidal.
The zona pellucida begins to form between the oocyte and the follicular
cells. The follicular cells become multilayered, and the surrounding stromal
cells begin to form the theca interna and the theca externa. The boundary
between the two theca layers is indistinct and the theca externa blends
into the surrounding stroma.
3. Secondary follicles (vesicular)
When follicles reach about 200 Ám in size, pools of fluid begin to accumulate
between the follicular cells (granulosa cells) and these eventually coalesce
into one central mass of follicular fluid in a space called the antrum. The
oocyte then lies to one side of the follicle. Pick out a late secondary follicle,
preferably one in which the oocyte has been included in the section. Starting
with the oocyte, find the zona pellucida. The several layers of
follicular cells forming a hillock and encompassing the oocyte constitute the
cumulus oophorus. The follicular basement membrane separates the nonvascular
follicular cells from the vascular theca cells. The theca cells closest
to the follicular basement membrane have enlarged and differentiated into steroid
secreting cells. These constitute the theca interna and may form more
than one layer in some areas around the follicle and be absent in others. Further
out, where the cells gradually appear more flattened but are still oriented
around the follicle is the theca externa. The theca externa is often
poorly developed and gradually blends with the multi-oriented interstitial cells
of the ovarian stroma. Arterioles and venules may be seen primarily associated
with the theca externa, while a capillary network is found in the theca interna.
4. Mature follicle (Graffian follicle)
In mature follicles antrum and follicle are maximally developed (2.5 cm). The
follicle extends through the full thickness of the cortex and bulges from the
surface of the ovary. There are no mature follicles on these slides.
B. Atretic Follicles
Few follicles, grow up to the point of ovulation. Most begin to grow
and then degenerate. In young follicles the oocytes degenerate first.
In secondary follicles, early changes include the presence of follicular
cells floating in the antral fluid and the invasion of fine blood vessels
and connective tissue into the granulosa cell layer. In these follicles
the granulosa cells degenerate first, then the oocyte; the degenerating
tissue is replaced by connective tissue, macrophages, and capillaries.
The follicle collapses, and the follicular basement membrane becomes wavy
and thickens into a mass of hyaline (i.e., refractile) material called
the glassy membrane. Locate the glassy membrane, a wavy, refractile,
pink-staining line, usually U-shaped or circular. This and its associated
cells are terminal remnants of atretic follicles. The process of atresia
can take several months.
C. Corpus Luteum
A mature follicle extends throughout the thickness of the cortex, pushes into
the medulla and forms a bulge on the surface of the ovary. At ovulation the
follicle ruptures and extrudes its oocyte surrounded by its zona pellucida and
corona radiata cells. Bleeding into the antrum occurs and the follicle shrinks
and collapses, throwing the theca and granulosa layers into folds. This structure,
called the corpus hemorrhagicum, increases in size and the cells undergo mitosis
and morphological changes (luteinization). It is then called a corpus luteum
of ovulation (menstruation or spurium). If fertilization occurs, there is
further enlargement to form a corpus luteum of pregnancy (graviditatis
The corpus luteum of slide #80 is a body about one inch
in diameter with an angular cavity. With the reverse ocular or naked eye,
examine its shape and size. With 10x, note that the granulosa
lutein cells derived from the follicular (granulosa) cells are the
predominant and largest cell type.
The theca lutein cells, derived from the theca interna, are
smaller, fewer in number, and are located peripheral to the granulosa
lutein cells. Groups of these cells may be seen where there are connective
tissue infoldings. They appear as groups of crowded rounded nuclei with
empty looking cytoplasm (best seen on #80 odd). Under higher
magnification, compare the granulosa lutein cells with the theca lutein
cells. Note the abundance of capillaries among both cell types. At the
end of menstruation, the corpus luteum involutes, its cells degenerate,
yellowish lipochrome pigment is seen, and the area is invaded by fibroblasts
and macrophages. Over the succeeding months, these cells become pyknotic,
and the area is eventually changed into a pale scarred mass called the
corpus albicans (white body). This sinks deeper into the ovary
over months or years. On slide #81, examine a large, fairly recent
corpus albicans still reflecting the shape of the corpus luteum. On slide
#79 odd (ovary), a small, shrunken, more fibrous, and hence, older
corpus albicans may be found.
Oviduct (Fallopian or Uterine Tube)
The oviducts are paired tubes extending from the ovary to the uterus. They
are enclosed within a fold of peritoneum. The oviduct consists of (a)
an enlarged funnel-shaped region called the infundibulum, (b)
a tubular portion called the ampulla, (c) a constricted portion
called the isthmus, and (d) the intramural region which
passes through the uterine wall. The oviduct undergoes gradual morphological
changes from the infundibulum to the intramural portion. This includes a decrease
in the size of the lumen a decrease in branched folds and a thickening
of the muscle coats. The epithelium consists of ciliated columnar cells
and non-ciliated secretory (peg) cells. The ciliated cells are most abundant
at the infundibulum, and their relative number decreases gradually towards the
uterus. The height of the epithelium varies during the menstrual cycle, being
greatest during the proliferative phase.
Just prior to the extrusion of the oocyte from the ovary, it completes the
first meiotic division and arrests at metaphase of the second meiotic division
with the haploid number of chromosomes. It is now called a secondary oocyte
and enters the oviduct. Fertilization usually occurs at the junction of the
ampulla and isthmus.
A. Infundibulum and Ampulla
Slide #83 (even and odd) both contain sections of infundibulum
and ampulla. It can be difficult to tell where the infundibulum ends and
the ampulla begins. Slide #83 odd is a longitudinal section through
the infundibulum and ampulla. Since the tube is twisted, portions of the
tube may be in oblique or cross-section. With the reverse ocular or scanning
lens, locate the infundibulum with its fimbria at the extreme
end of the tissue. At the opposite end is the ampulla. Notice the
gradual decrease in size of both the lumen and the mucosal folds and the
gradual increase in the thickness of muscle coat. Examine the epithelium
and notice the patches of ciliated cells.
On slide #83 (even) find the large, funnel-shaped infundibulum. The
muscle wall may be present on only one side. On the other side are large, highly
branched mucosal folds (fimbria). Locate the ampulla. The mucosal folds
are branched and prominent. The epithelium has abundant patches of ciliated
cells. The lamina propria and serosa are vascular and the muscle wall thin.
On slide #82 (odd and even), find the cross-section of the isthmus
(round in outline) and note that the folds of the mucous membrane
are relatively simple, and their lamina propria is very vascular.
The mucosal folds are covered by columnar epithelium with only
a few ciliated cells. The muscle wall is conspicuous with
a thick inner circular and a thinner outer longitudinal component. At
the outer edges of the oviduct, locate the covering serosal epithelium
(may be absent), and note that the serosa is thick and contains abundant
The intramural (interstitial) portion of the oviduct is found
within the myometrium of the uterine wall. Using the scanning lens, find
on slide #82 (even, up to box #186 only) the small lumen of the
intramural duct, which is lined by columnar epithelium. There may
be blood vessels nearby in the uterine tissue with a lumen as large or
larger lined by squamous epithelium. Note the size of the oviduct lumen,
the near absence of mucosal folds and under higher magnification, the
scarcity of ciliated cells. The intramural oviduct is encircled by its
own muscular coat which can be distinguished from the multi-oriented uterine
muscle. This slide also contains a section through the isthmus.
The uterus is a muscular, pear-shaped organ composed of the body, the
isthmus and the cervix. The uterine mucosa is called the endometrium,
the muscle layer is the myometrium, and the serosa (over the fundus and
posterior surface) or the adventitia is the perimetrium.
A narrow portion of the endometrium adjacent to the myometrium is not shed
at menstruation and is called the stratum basalis. Cells from the glandular
epithelium, stroma and blood vessels of the stratum basalis proliferate and
restore the endometrium after menstruation. The more superficial and thicker
layer of the endometrium, which is formed after menstruation, is called the
The blood supply of the endometrium comes from the circumferentially oriented
arcuate arteries of the myometrium. Branches from these arteries pass to the
endometrium and form the straight arteries which supply the stratum basalis
and the coiled (spiral) arteries which supply the stratum functionalis. The
straight arteries do not undergo cyclic changes, and the constant blood supply
to the stratum basalis contributes to its stability. Before the onset of menstruation
the coil arteries constrict causing ischemia and destruction of the stratum
functionalis. At menses the stratum functionalis is shed. At the end of menses
the proliferative or follicular phase begins.
A. Menstral Cycle
1. Proliferative Phase
Examine a uterus in the proliferative or follicular phase on
slide #85. (Slide #85 is late proliferative). With the reversed
ocular, locate the endometrium and choose an area where the glands
appear to be cut in longitudinal section. Examine the full thickness of
the endometrium noting that the stroma is more compact towards
the stratum basalis. Under higher magnification, note that
a columnar epithelium (with a few scattered ciliated cells) lines
the surface and the glands. The glands are straight or slightly wavy.
The myometrium is composed of three indistinct layers of muscle.
2. Secretory Phase
Examine a uterus in the secretory or luteal phase (slide #86),
both odd and even should be seen. With the reversed ocular and higher
magnification, locate the endometrium, (on one side of the tissue
block) with its characteristically dilated or sacculated glands.
Under higher magnification notice that the stroma is edematous
(increased interstitial fluid) in slide #86 odd, and shows large
empty spaces. Immediately adjacent to the myometrium, the bases
of the glands are located in the stratum basalis.
3. Menstrual Phase
Slide #87 even is a late menstrual uterus. The free surface
of the endometrium has lost its epithelium, and the stroma
and broken glands and blood vessels protrude. Little remains
of the stratum functionalis. Most of the glands and stroma
belong to the stratum basalis and will not be shed. There is no
evidence of epithelialization of the denuded surface, so this section
was taken before the end of the menstrual period. Slide #87 odd
is of a menstrual uterus just after the beginning of menstruation. In
some areas the epithelium is still intact though the underlying stroma
is swollen with extravasated blood.
Slide #88 (odd and even), is a section through one side of the
cervix. The lumenal surface of the endocervix (region of the cervical
canal) is lined with columnar epithelium. At or near where the
tissue curves (region of the external os) the epithelium
changes from simple columnar to stratified squamous (region of
the ectocervix). The highest incidence of gynecological cancers
occurs in the region of the external os. In the region of the endocervix,
there are several cervical glands (these are best seen on slide
#88 odd). Some glands project under the stratified squamous epithelium
of the ectocervix and may show cystic dilations. The muscle of
the cervix is relatively deficient compared to the rest of the uterus
and arranged in irregular bundles and intermingled with dense connective
tissue. Note the abundance of blood vessels.
The vagina is a distensible fibromuscular tube continuous above with
the cervix and opening into the vestibule of the female external genitalia.
The wall of the vagina consists of three layers: mucosa, muscularis, and
adventitia. Slide #89 has only the mucosa and part of the muscularis.
The mucosa consists of an epithelium and a lamina propria. A muscularis
mucosa is absent. Examine the noncornified stratified squamous epithelium
(note nuclei at all levels). The epithelial cells accumulate glycogen
and in routine H & E sections they appear vacuolated since the glycogen
is dissolved during slide preparation. The lamina propria consists of
thick, dense connective tissue with varying numbers of leukocytes. Elastic
fibers are plentiful beneath the epithelium but cannot be differentiated with
H & E stains. Glands and gland openings are lacking. The lamina propria
contains many blood vessels.
The smooth muscle of the muscularis is arranged in interlacing bundles,
which do not occupy well defined layers. In a few slides, striated fibers are
present in the outer muscle coat.
The fully developed mammary gland is a compound tubulo-alveolar gland which
consists of 15 to 25 lobes. Each lobe is composed of the ducts and alveoli which
drain into one lactiferous duct. The degree of glandular development depends
on the sex, age, and the functional condition of the reproductive system. In
the sexually mature, non-pregnant female, the glands consist primarily of a
duct system embedded in a large amount of fat and connective tissue. When pregnancy
occurs, the duct system undergoes proliferation and secretory alveoli develop
from the ends of the duct branches. This growth continues throughout pregnancy
so that much of the fat and connective tissue is replaced by secretory alveoli
A. Non-lactating Mammary Gland
Slide #91 -(NOTE: on slide #91 odd, there is a
large encapsulated area with loose connective tissue, degenerated glands,
and enlarged cystic ducts and glands. This is a fibroadenoma. Study
the rest of the tissue which is normal). The lobes of the mammary gland
are further subdivided into lobules. On slide #91 locate the lobules
which are separated by dense interlobular connective tissue and
fat cells. The epithelial cells within the lobule are chiefly
duct elements and are contained in a loose connective tissue which
lacks fat cells. Interlobular ducts can be observed in the dense
interlobular connective tissue.
B. Lactating Mammary Gland
On slide #92, (examine even and odd) notice a tremendous increase
in the number of lobules. Within the lobules, secretory alveoli
are seen in varying functional states. In some places the secretory portions
are filled with milk (wide lumen and thin lining cells) and in
other areas they are not (lumen narrow and epithelial height is increased).
Some of the epithelium appears vacuolated due to lipid extraction
during histological preparation. Try to find the nuclei of a myoepithelial
cell (within the basement membrane). Note the presence of plasma
cells within the intralobular connective tissue and the decrease in
interlobular connective tissue. How can you differentiate the lactating
mammary gland from the thyroid gland?
Slide #93 with reverse ocular examine the general topography
of the nipple. Note the dark staining epidermal covering, dense connective
tissue stroma, and the lactiferous ducts. Under low power observe the
highly folded stratified squamous epithelium, dermal papillae and
sebaceous glands. At higher magnification observe the pigmentation
in the basal cells of the epithelium. Bundles of smooth muscle
run in various planes in the stroma, and the lactiferous ducts
can be seen as large, elongated spaces lined with one or two layers of