1. histology reproductive system.ppt

Histology of Reproductive
Organs
By Dr. Girmay G. (MD and MSc in Medical
Anatomy, Assistant professor )
1

The Male Reproductive System
The male reproductive
system consists of:
Testes
Genital ducts
Accessory sex glands
Penis
 The two primary
functions of the testis
are spermatogenesis,
and steroidogenesis
2

TESTES
 The adult testes are paired ovoid organs that lie within the
scrotum, located outside the body cavity.
 Each testis (or testicle) is surrounded by a dense connective
tissue capsule, the tunica albuginea , which thickens on the
posterior side to form the mediastinum testis .
 From this fibrous region, septa penetrate the organ and divide it
into about 250 pyramidal compartments or testicular lobules.
 Each lobule contains sparse connective tissue with endocrine
interstitial cells (or Leydig cells ) secreting testosterone, and
 one to four highly convoluted seminiferous tubules in which
sperm production occurs.
4

Cont..
 The testes develop retroperitoneally in the dorsal wall of the
embryonic abdominal cavity and are moved during fetal
development.
 During migration from the abdominal cavity, each testis carries
with it a serous sac, the tunica vaginalis , derived from the
peritoneum.
 A permissive temperature of about 34°C is maintained in the
scrotal sac by various mechanisms.
5

Cont..
 Each testicular artery is surrounded by a rich pampiniform
venous plexus containing cooler blood from the testis, which
draws heat from the arterial blood by a countercurrent heat-
exchange system.
 Evaporation of sweat from the scrotum
 Relaxation or contraction of the thin dartos muscle of the
scrotum and the cremaster muscles of the spermatic cords
6

Cont..
Interstitial Tissue
 The interstitial tissue of the testis between the seminiferous
tubules consists of sparse connective tissue containing
 fibroblasts, lymphatics, and blood vessels including fenestrated
capillaries.
 During puberty interstitial cells, or Leydig cells, develop as large
round or polygonal cells with central nuclei and eosinophilic
cytoplasm rich in small lipid droplets.
 These cells produce the steroid hormone testosterone.
8

Cont..
 Testosterone is synthesized by enzymes present in the smooth
ER and mitochondria
 Testosterone secretion by interstitial cells is triggered by the
pituitary gonadotropin, luteinizing hormone (LH), which is also
called interstitial cell stimulating hormone (ICSH).
9

Cont..
Seminiferous Tubules
 Sperm are produced in the seminiferous tubules at a rate of
about 2 × 108 per day in the young adult.
 Each testis has from 250 to 1000 such tubules in its lobules, and
each tubule measures 150 to 250 μm in diameter and 30 to 70
cm in length.
 The combined length of the tubules of one testis totals about
250 m.
 Each tubule is actually a loop linked by a very short, narrower
segment, the straight tubule, to the rete testis,
 About 10-20 efferent ductules connect the rete testis to the
head of the epididymis.
10

Cont..
 Each seminiferous tubule is lined with a complex, specialized
stratified epithelium called germinal or spermatogenic
epithelium.
 The basement membrane of this epithelium is covered by
fibrous connective tissue, with an innermost layer containing
flattened, smooth muscle-like myoid cells.
 The germinal epithelium consists of two types of cells
Large nondividing Sertoli cells: physically and metabolically
support developing sperm cell precursors.
 Dividing cells of the spermatogenic lineage
• Comprise four to eight concentric cell layers and produce the
cells that become sperm. 14

Seminiferous tubule and interstitial cells.
15

SPERMATOGENESIS
• Spermatogenesis is the process by which spermatogonia develop
into sperm.
• Spermatogenesis, the process by which sperm are produced
involves a complex and unique series of events.
• It begins shortly before puberty, under the influence of rising levels of
pituitary gonadotropins, and continues throughout life.
• Duration of spermatogenesis in humans is approximately 74 days.
• Spermatogenesis is the first part of sperm production, including stem
cell mitosis and meiosis, and
• Spermiogenesis is the final differentiation process occurring in the
haploid male germ cells
16

Cont..
Spermatogenesis
 Takes in 3 phases
Spermatogonial phase
Spermatocyte phase
(meiosis)
Spermatid phase
(spermiogenesis)
17

Cont..
Spermatocytogenesis
 Spermatogonia is small round cells about
12 μm in diameter.
 These cells occupy a basal niche in the
epithelial wall of the tubules, next to the
basement membrane and closely
associated with Sertoli cell surfaces
18

Cont..
Spermatogonia with dark, ovoid nuclei act as stem cells,
dividing infrequently.
 Type A spermatogonia each undergo several unique clonal
divisions that leave most of the cells interconnected as a
syncytium.
These become type B spermatogonia, which have more
spherical and pale nuclei.
Each type B spermatogonium then undergoes a final mitotic
division to produce two cells that grow in size and become
primary spermatocytes.
They are spherical cells with euchromatic nuclei
19

Cont..
The primary spermatocyte has 46 (44 + XY) chromosomes, the
diploid number.
Soon after their formation, these cells enter the first meiotic
prophase that lasts about 3 weeks.
The primary spermatocytes are the largest cells of the
spermatogenic lineage.
Homologous chromosomes separate in the first meiotic
division, which produces smaller cells called secondary
spermatocytes with only 23 chromosomes.
20

Cont..
Secondary spermatocytes are rare in testis sections because
they are very short-lived cell.
Division of each secondary spermatocyte separates the
chromatids of each chromosome and produces two haploid
cells called spermatids each of which contains 23
chromosomes.
21

Seminiferous tubules: Sertoli cells and
spermatogenesis
23

Clonal nature of spermatogenesis
24

Cont..
Spermiogenesis
 Spermiogenesis, the final phase of sperm production, is the
temperature-sensitive process by which spermatids differentiate into
spermatozoa.
 Spermiogenesis is commonly divided into four phases:
 In the Golgi phase the cytoplasm contains a prominent Golgi
apparatus near the nucleus, mitochondria, paired centrioles, and free
ribosomes.
 In the cap phase the acrosomal cap spreads over about half of the
condensing nucleus.
 In the acrosome phase the head of the developing sperm, containing
the acrosome and the condensing nucleus, remains embedded in the
Sertoli cell
 In the maturation phase of spermiogenesis, unneeded cytoplasm is
shed as a residual body.
Spermatids are released into the lumen of the seminiferous tubules
during the process called spermiation. 25

Cont..
Sertoli Cells
 They are tall columnar or pyramidal epithelial cells that form
the basal lamina of the seminiferous tubules.
 All cells of the spermatogenic lineage are closely associated
with the extended surfaces of Sertoli cells and depend on them
for metabolic and physical support.
 Sertoli cells adhere to the basal lamina and their apical ends
extend to the lumen.
 Each Sertoli cell supports 30 to 50 developing germ cells.
26

Cont..
Ultrastructurally Sertoli cells are seen to contain abundant SER,
some rough ER, well-developed Golgi complexes, numerous
mitochondria, and lysosomes
Important in Sertoli cell function are to form a blood-testis
barrier within the seminiferous epithelium.
 The tightest blood-tissue barrier in mammals, this physical
barrier is one part of a system that prevents autoimmune
attacks against the unique spermatogenic cells.
27

Cont..
Related to their role in establishing the blood-testis barrier,
Sertoli cells have three general functions:
 Support, protection, and nutrition of the developing
spermatogenic cells:
 Exocrine and endocrine secretion: Production of nutrients and
androgen-binding protein (ABP), glycoprotein inhibin, müllerian-
inhibiting substance (MIS)
 Phagocytosis: excess cytoplasm shed as residual bodies is
phagocytosed and digested by Sertoli cell lysosomes.
28

INTRATESTICULAR DUCTS
The intratesticular ducts are
 The straight tubules (or tubuli recti),
 The rete testis, and
 The efferent ductules.
 All of which carry spermatozoa and liquid from the
seminiferous tubules to the duct of the epididymis.
 The loops of seminiferous tubules join the rete testis by the
short straight tubules, which are lined initially only by Sertoli
cells.
These empty into the rete testis, an interconnected network of
channels lined with cuboidal epithelium and supported by
connective tissue of the mediastinum.
29

Cont..
The rete testis drains into about 20 efferent ductules.
It is lined by an unusual epithelium in which groups of non-
ciliated cuboidal cells alternate with groups of taller ciliated cells
and give the tissue a characteristic scalloped appearance.
The nonciliated cells absorb most of the fluid secreted by the
Sertoli cells of seminiferous tubules.
This absorption and the ciliary activity create a fluid flow that
carries sperm out of the testis toward the epididymis.
A thin layer of circularly oriented smooth muscle cells in the
walls of efferent ductules aids sperm movement into the duct of
the epididymis.
30

Seminiferous tubules, straight tubules and rete
testis.
31

EXCRETORY GENITAL DUCTS
The excretory genital ducts includes
 The epididymis,
 The ductus (or vas) deferens, and
 The urethra.
They transport sperm from the scrotum to the penis during
ejaculation.
33

Cont..
Epididymis
The long, coiled duct of the epididymis, surrounded by
connective tissue,
 It lies in the scrotum along the superior and posterior
sides of each testis.
It is 4 to 5 m in length.
It includes a head region where the efferent ductules
enter, a body, and a tail opening into the ductus
deferens.
34

Cont..
While passing through this duct, sperm become motile and
their surfaces and acrosomes undergo final maturation steps.
Fluid within the epididymis contains glycolipid decapacitation
factors
 Bind sperm cell membranes and block acrosomal reactions and
fertilizing ability.
The epididymal duct is lined with pseudostratified columnar
epithelium.
 It consists of columnar principal cells, with characteristic long
stereocilia, and small round stem cells
35

Cont..
The principal cells secrete glycolipids and glycoproteins, but
also absorb water and remove residual bodies or other debris
not removed earlier by Sertoli cells.
The duct epithelium is surrounded by smooth muscle cells,
arranged as inner and outer longitudinal layers as well as a
circular in the tail of the epididymis.
Peristaltic contractions move the sperm along the duct and
empty the body and tail regions at ejaculation.
36

Cont..
Ductus or Vas Deferens
A long straight tube with a thick, muscular wall and a relatively
small
lumen, continues toward the prostatic urethra.
Its mucosa is slightly folded longitudinally, the lamina propria
contains many elastic fibers, and the epithelial lining is
pseudostratified with some cells having sparse stereocilia.
The very thick muscularis consists of longitudinal inner and
outer layers and a middle circular layer.
The muscles produce strong peristaltic contractions during
ejaculation, which rapidly move sperm along this duct from the
epididymis. 38

Cont..
The ductus (vas) deferens forms part of the spermatic cord,
which also includes the testicular artery, the pampiniform
plexus, and nerves.
 Each ductus passes over the urinary bladder where it enlarges
as an ampulla (L. a small bottle).
 Within the prostate gland, the ends of the two ampullae merge
with the ducts of the two seminal vesicles, joining these ducts to
form the ejaculatory ducts which open into the prostatic urethra.
39

Summary of histology and function of male genital ducts
41

MEDICAL APPLICATION
The accessibility of the ductus (vas) deferens in the spermatic
cords allows for the most common surgical method of male
contraception: vasectomy.
In this procedure a very small incision is made through the
scrotal skin near the two ducts and each vas is exposed, cut,
and the two ends (or only the end leading to the abdomen) are
cauterized and tied.
After vasectomy sperm are still produced, but they degenerate
and are removed by macrophages in the epididymis.
42

ACCESSORY GLANDS
Produce secretions that are mixed with sperm during
ejaculation to produce semen and that are essential for
reproduction.
The accessory genital glands are
 The seminal vesicles (or glands),
 The prostate gland, and
 The bulbourethral glands
43

Cont..
Seminal Vesicles
The two seminal vesicles consist of highly tortuous tubes, each
about 15 cm long, enclosed by a connective tissue capsule.
The unusual mucosa of the tube displays a great number of
thin, complex folds that fill much of the lumen.
The folds are lined with simple or pseudostratified columnar
epithelial cells rich in secretory granules.
The lamina propria contains elastic fibers and is surrounded by
smooth muscle with inner circular and outer longitudinal layers
that empty the gland during ejaculation.
45

Cont..
The seminal vesicles are exocrine glands in which production
of their viscid, yellowish secretion depends on testosterone.
Fluid from seminal vesicles typically makes up about 70% of
the ejaculate and its components include the following:
Fructose, a major energy source for sperm
Prostaglandins, stimulate activity in the female reproductive
tract; and
Fibrinogen, allows semen to coagulate after ejaculation.
46

Cont..
Prostate Gland
 The prostate gland is a dense organ that surrounds the urethra
below the bladder.
 It is approximately 2 cm × 3 cm × 4 cm in size and weighs
about 20g.
 The prostate is a collection of 30 to 50 tubuloacinar glands
embedded in a dense fibromuscular stroma.
 Ducts from individual glands may converge but all empty
directly into the prostatic urethra.
48

Cont..
The glands are arranged in three major zones around the
urethra:
The transition zone occupies only about 5% of the prostate
volume, surrounds the superior portion of the urethra, and
contains the periurethral mucosal glands.
The central zone comprises 25% of the gland’s tissue and
contains the periurethral submucosal glands with longer ducts.
The peripheral zone, with about 70% of the organ’s tissue,
contains the prostate’s main glands.
49

Cont..
The tubuloacinar glands of the prostate are all lined by a simple
or pseudostratified columnar epithelium and
They produce fluid that contains various glycoproteins,
enzymes, and small molecules such as prostaglandins and is
stored until ejaculation.
A clinically important product of the prostate is prostate-specific
antigen (PSA), a 34-kDa serine protease that helps liquefy
coagulated semen for the slow release of sperm after
ejaculation.
Elevated levels of circulating PSA indicate abnormal glandular
mucosa typically due to prostatic carcinoma or inflammation. 51

Cont..
Small spherical concretions, 0.2 to 2 mm in diameter and often
partially calcified, are normally present in the lumens of many
prostatic tubuloacinar glands.
These concretions, called corpora amylacea, containing
primarily deposited glycoproteins and keratan sulfate.
Have no physiologic or clinical significance.
52

MEDICAL APPLICATION
The prostate gland is prone to three common problems:
(1) chronic prostatitis, usually involving bacteria or other
infectious agents;
(2) nodular hyperplasia or benign prostatic hypertrophy, occurring
mainly in the periurethral mucosal glands where it often leads to
compression of the urethra and problems with urination; and
(3) prostate cancer (adenocarcinoma), the most common cancer
in nonsmoking men, occurring mainly in glands of the peripheral
zone.
54

Cont..
Bulbourethral Glands
The paired round bulbourethral glands (or Cowper glands), 3-5
mm in diameter, are located in the urogenital diaphragm and
empty into the proximal part of the penile urethra.
Each gland has several lobules with tubuloacinar secretory
units surrounded by smooth muscle cells.
During erection the bulbourethral glands release a clear mucus-
like secretion that coats and lubricates the urethra in
preparation for the imminent passage of sperm.
55

Cont..
PENIS
The penis consists of three cylindrical masses of erectile tissue,
plus the penile urethra, surrounded by skin.
 Two of the erectile masses—the corpora cavernosa—are dorsal;
the ventral corpus spongiosum surrounds the urethra.
 At its end the corpus spongiosum expands, forming the glans.
 Most of the penile urethra is lined with pseudostratified
columnar epithelium.
 In the glans, it becomes stratified squamous epithelium
continuous with that of the thin epidermis covering the glans
surface.
56

Cont..
Small mucus-secreting urethral glands are found along the
length of the penile urethra.
In uncircumcised men the glans is covered by the prepuce or
foreskin, a retractable fold of thin skin with sebaceous glands on
the internal surface.
 The corpora cavernosa are each surrounded by a dense
fibroelastic layer, the tunica albuginea.
 All three erectile tissues consist of many venous cavernous
spaces lined with endothelium.
 Central arteries in the corpora cavernosa branch to form
nutritive arterioles and small coiling helicine arteries.
58

Cont..
Penile erection involves blood filling the cavernous spaces in
the three masses of erectile tissue.
Triggered by external stimuli to the CNS, erection is controlled
by autonomic nerves in these vascular walls.
Parasympathetic stimulation relaxes the trabecular smooth
muscle and dilates the helicine arteries.
Beginning at ejaculation, sympathetic stimulation constricts the
helicine arteries and trabecular muscle
59

Female Reproductive System
The female reproductive system consists of internal sex organs
and external genital structures.
The internal female reproductive organs are located in the
pelvis
 The external genital structures (external genitalia) are situated
in the anterior part of the perineum known as the vulva.
The internal female reproductive organs are the ovaries,
uterine tubes, uterus, and vagina.
The external genitalia include the mons pubis, labia majora and
minora, clitoris, vestibule and opening of the vagina, hymen,
and external urethral orifice.
62

OVARIES
Ovaries are almond-shaped bodies approximately 3 cm long, 1.5 cm wide,
and 1 cm thick.
There are three cell types in the normal ovary:
 the multipotent surface (coelomic) epithelium,
 the totipotent germ cells, and
 the sex cord–stromal cells
Each ovary is covered by a simple cuboidal epithelium, the surface (or
germinal) epithelium.
Overlying a layer of dense connective tissue capsule, the tunica albuginea.
Production of gametes and steroid hormones are the two major functions
of the ovary.
65

Cont..
The ovaries have two interrelated functions: gametogenesis
(the production of gametes) and steroidogenesis (the
production of steroids).
In women, the production of gametes is called oogenesis.
Developing gametes are called oocytes; mature gametes are
called ova
66

Cont..
The ovary is composed of a cortex and a
medulla.
A section through the ovary reveals two
distinct regions:
 The medulla or medullary region
 is located in the central portion of the ovary and
contains loose connective tissue
 A mass of relatively large contorted (twisted) blood
vessels, lymphatic vessels, and nerves.
 The cortex or cortical region
 is found in the peripheral portion of the ovary
surrounding the medulla.
• contains the ovarian follicles embedded in a
richly cellular connective tissue.
67

• The adult ovary can be subdivided
into three regions:
• the cortex,
• the medulla, and
• the hilus regions.
• The cortex consists of
• the surface epithelium
• tunica albuginea
• ovarian follicles (primordial, primary
secondary
• small, medium, large Graafian follicle and
• corpora lutea
• The medulla consists of
• large blood vessels and nerves.
• The hilus contains
• large spiral arteries
• the hilus or ovary Leydig cells
NB: There is no distinct border between the ovarian cortex
and medulla

Cont..
Early Development of the Ovary
 In the first month of embryonic life, primordial germ cells
migrates from the yolk sac to the gonadal primordia.
 A 2-month embryo 600,000 oogonia
 More than 7 million by the fifth month.
 Beginning in the third month, oogonia begin to enter the
prophase of the first meiotic division.
 These cells arrested in meiosis are called primary oocytes
69

Cont..
 By the seventh month of development, most oogonia have
transformed into primary oocytes within follicles
 At puberty the ovaries contain about 300,000 oocytes.
Only about 450 oocytes are liberated from ovaries by ovulation.
70

Cont..
Ovarian Follicles
An ovarian follicle consists of an oocyte surrounded by one or
more layers of epithelial cells within a basal lamina.
The follicles that are formed during fetal life primordial follicles
consists of a primary oocyte.
The oocyte in the primordial follicle is spherical and about 25
μm in diameter, with a large nucleus containing chromosomes
in the first meiotic prophase.
The organelles tend to be concentrated near the nucleus and
include numerous mitochondria, several Golgi complexes, and
extensive RER
71

Cont..
Beginning in puberty with the release of FSH from the pituitary,
a small group of primordial follicles each month begins a
process of follicular growth.
This involves
Growth of the oocyte,
Proliferation and changes in the follicular cells,
Proliferation and differentiation of the stromal fibroblasts around
each follicle.
74

Cont..
Oocyte differentiation includes the following:
 Growth of the cell and nuclear enlargement;
 Mitochondria becoming more numerous and uniformly
distributed;
 RER becoming much more extensive and Golgi complexes
enlarging and moving peripherally; and
 Formation of specialized secretory granules called cortical
granules containing various proteases.
75

Cont..
Follicular cells undergo mitosis and form a simple cuboidal
epithelium around the growing oocyte.
The follicle is now called a unilaminar primary follicle
The follicular cells continue to proliferate, forming a stratified
follicular epithelium, the granulosa
Follicular cells are now termed granulosa cells and the follicle is
a multilaminar primary follicle.
Between the oocyte and the first layer of granulosa cells the
zona pellucida, 5 to 10 μm thick and containing four
glycoproteins secreted by the oocyte.
76

Cont..
Stromal cells immediately outside each growing primary follicle
differentiate to form the follicular theca.
A well-vascularized endocrine tissue, the theca interna
• Characteristic of steroid-producing cells
• Possess a large number of luteinizing hormone (LH) receptors.
A more fibrous theca externa with fibroblasts and smooth
muscle
77

Multilaminar primary follicle
78

Cont..
When the stratum granulosum reaches a thickness of 6 to 12
cell layers, ﬂuid-ﬁlled cavities appear among the granulosa
cells.
As the hyaluronan-rich fluid called liquor folliculi continues to
accumulate among the granulosa cells, the cavities begin to
coalesce, eventually forming a single, crescent shaped cavity
called the antrum.
The follicle is now identified as a secondary follicle or antral
follicle .
80

Cont..
As the secondary follicle increases in size, the antrum, lined by
several layers of granulosa cells, also enlarges.
 The granulosa cells form a thickened mound, the cumulus
oophorus, which projects into the antrum.
 The cells of the cumulus oophorus that immediately surround the
oocyte and remain with it at ovulation are referred to as the corona
radiata.
 The mature or Graafian follicle contains the mature secondary
oocyte.
 The mature follicle, also known as a Graaﬁan follicle, has a
diameter of 10 mm or more. 82

Antral follicle and preovulatory follicle
84

Stages of ovarian follicles, from primordial to
mature.
86

Ovulation & Its Hormonal Regulation
Ovulation is the hormone-stimulated process by which the
oocyte is released from the ovary.
Ovulation normally occurs midway through the menstrual cycle,
that is, around the 14th day of a typical 28-day cycle.
In the hours before ovulation, the mature dominant follicle
bulging against the tunica albuginea develops a whitish or
translucent ischemic area, the stigma, in which tissue
compaction has blocked blood flow.
Before ovulation the oocyte completes the first meiotic division
The cell is now the secondary oocyte and the other becomes
the first polar body.
88

Cont..
A combination of hormonal changes and enzymatic effects is
responsible for the actual release of the secondary oocyte
These factors include:
 Increase in the volume and pressure of the follicular fluid
 Enzymatic proteolysis of the follicular wall by activated
plasminogen
 Hormonally directed deposition of glycosaminoglycans
between the oocyte–cumulus complex and the stratum
granulosum
 Contraction of the smooth muscle fibers in the theca externa
layer, triggered by prostaglandins.
89

Cont..
The increased level of GnRH causes a surge of LH release
triggers a sequence of major events in and around the dominant
follicle:
Meiosis I is completed by the primary oocyte
Granulosa cells are stimulated to produce much greater
amounts of both prostaglandin and extracellular hyaluronan
Ballooning at the stigma, the ovarian wall weakens
Smooth muscle contractions begin in the theca externa
 The increasing pressure with the follicle and weakening of the
wall lead to rupture of the ovarian surface at the stigma.
90

Cont..
Corpus Luteum
 The collapsed follicle undergoes reorganization into the corpus
luteum after ovulation.
After ovulation, the granulosa cells and theca interna of the
ovulated follicle reorganize to form a larger temporary
endocrine gland, the corpus luteum.
 A lipid-soluble pigment, lipochrome, in the cytoplasm of the
cells gives them a yellow appearance in fresh preparations.
91

Cont..
The short-term fate of the corpus luteum depends on whether a
pregnancy occurs.
The ovulatory LH surge causes the corpus luteum to secrete
progesterone for 10 to 12 days.
Without further LH stimulation and in the absence of
pregnancy, both major cell types of the corpus luteum cease
steroid production and undergo apoptosis.
92

Cont..
A consequence of the decreased secretion of progesterone is
menstruation, the shedding of part of the uterine mucosa.
The corpus luteum that persists for part of only one menstrual
cycle is called a corpus luteum of menstruation.
Remnants from its regression are phagocytosed by
macrophages, produce a scar of dense connective tissue called
a corpus albicans
 If fertilization and implantation occur, the corpus luteum
increases in size to form the corpus luteum of pregnancy.
Corpus luteum of pregnancy is maintained by HCG for 4 to 5
months.
94

Hormonal regulation of ovulation
• Growth of follicles during the first half of the menstrual cycle is
stimulated by FSH from pituitary gland.
97

• Growing follicles produce estrogen, whose increased output exerts a
negative feedback on the FSH production causing an LH surge
98

• The increased secretion of LH causes:
1. Final follicle maturation and ovulation
99

2. Formation of the corpus luteim which produces estrogen,
progesterone & inhibin that inhibit LH production, causing
degeneration of the corpus luteim after 14 days, unless fertilization
occurs.
100

• If pregnancy takes place, human chorionic gonadotropin produced by
the developing placenta maintains the corpus luteim in the absence of
LH.
101

Clinical correlation
• It also is the fifth leading
contributor to cancer
mortality in women,
• Tumors of the ovary are
amazingly varied.
• This diversity is attributable
to the presence of three cell
types in the normal ovary:
• the multipotent surface
(coelomic) epithelium,
• the totipotent germ cells,
and
• the sex cord–stromal cells
103

 Is about 12 cm long, and has four pats: infundibulum with fimbriae,
ampulla, isthmus and intramural or interstitial part.
Histology of the uterine tube
104

 The wall of the oviduct consists of 3 layers
 Folded mucosa
 Thick, well-defined muscularis; Circular (or spiral) and longitudinal
layers of smooth muscle
 Thin serosa covered by visceral peritoneum with mesothelium.
Histology of the oviduct
105

 The mucosal lining is simple columnar epithelium composed of
two kinds of cells—ciliated and nonciliated.
 Ciliated cells are most numerous in the infundibulum and ampulla.
 The wave of the cilia is directed toward the uterus.
 Nonciliated, peg cells are secretory cells that produce the fluid
that provides nutritive material for the ovum.
107

• Lamina propria
– Made by loose connective tissue that can act like the uterus in an abnormal
implantation.
109

• Muscular layer
– Made by: inner circular or spiral and outer longitudinal layers.
• Serosa making the most outer layer.
110

 Pear-shaped organ with thick, muscular walls
 Has body (corpus), fundus and cervix parts.
 The lumen of the cervix, the cervical canal, has constricted
openings at each end:
 The internal os (L. os, mouth) opens to the main uterine lumen
and
 The external os to the vagina
Histology of the uterus
112

 The uterine wall is composed of three
layers
 From the lumen to outward they are as
follows
 The endometrium is the mucosa of the
uterus.
 The myometrium is the thick muscular
layer. It is continuous with the muscle
layer of the uterine tube and vagina.
 The perimetrium, the outer serous layer
or visceral peritoneal covering of the
uterus
Histology of the body and funds of uterus
113

Cont..
 Both myometrium and endometrium
undergo cyclic changes each month to
prepare the uterus for implantation of an
embryo.
 These changes constitute the menstrual
cycle.
 The myometrium forms a structural and
functional syncytium.
 The myometrium is the thickest layer of
the uterine wall.
 The middle muscle layer contains
numerous large blood vessels (venous 114

• Endometrium made by:
– Lining epithelium of:
• Simple ciliated columnar cells
• Simple columnar secretory cells
Endometrium
115

• Lamina propria
– Contain large amount of fibroblasts, ground substance, reticular
connective tissue and simple tubular glands (branched in deeper
portion).
Endometrium
116

• During reproductive life, the endometrium consists of two layers or
zones that differ in structure and function
 The stratum functionale or functional layer is the thick part of the
endometrium, which is sloughed off at menstruation.
 The stratum basale or basal layer is retained during menstruation
and serves as the source for the regeneration of the stratum
functionale.
• The stratum functionale is the layer that proliferates and
degenerates during the menstrual cycle.
Endometrium
117

– Undergoes cyclic changes in response to the ovarian
hormones
– Receives the coiled (spiral) arteries
– Subdivided based on the density of the lamina propria
Stratum functionale (pars functionalis) of endometrium
118

a. Stratum compactum
– Superficial and with large number of stromal cells that
appear epithelial cells.
b. Stratum spongiosum
– Deeper portion.
Stratum functionale (pars functionalis) of endometrium
119

• Deeper and thinner portion.
• Receives the straight arteries.
• Retained during menstruation.
• Contain the deeper parts of the uterine glands whose
lining cells replace covering epithelium after
mensuration.
Stratum basale (pars basalis) of endometrium
120

• The thickest tunic of the uterus
• Shows bundles of smooth muscle fibers separated by connective tissue
containing venous plexuses and lymphatics
• The smooth muscle forms interwoven layers
• Show 4 poorly defined layers.
– 1st and 4th layers are mainly longitudinal.
– The middle layers are highly vascular with arcuate arteries which give
the straight and coiled arteries.
Myometrium
121

 At pregnancy show hyperplasia and hypertrophy, and synthesis collagen.
 After pregnancy is reduced by reduction in the muscle size and destruction
and degradation of collagen.
Myometrium
122

• Made by serosa or adventitia
• Make the outer layer.
Perimetrium
123

Arterial supply to the endometrium.
125

Mucosa
• Two types of epithelial lining
1. Simple columnar epithelium
that secret mucus
2. Stratified squamous
epithelium covers the
external vaginal surface.
Histology of the uterine cervix
126

Transformation zone of the cervix
127

• Mucosa
– Do not shed during menstruation, but cyclic changes occur in the
amount and viscosity of its secretion.
128

• Contain cervical glands which are:
– Mucous secreting
– Extensively branched.
– At ovulation secrete watery mucous
– At pregnancy secrete more viscous mucous
129

 A few smooth
muscle fibers.
 Dense
connective
tissue that make
about 85% , and
undergo
collagenolysis
during cervical
dilatation.
130

Menstrual cycle
• Cyclic changes of the endometrium during the menstrual cycle are
represented by the proliferative, secretory, and menstrual phases.
• The menstrual cycle is a continuum of developmental stages in
the functional layer of the endometrium.
• It is ultimately controlled by gonadotropins secreted by the pars
distalis of the pituitary gland that regulate the steroid secretions of
the ovary.
• The cycle normally repeats every 28 days, during which the
endometrium passes through a sequence of morphologic and
functional changes.
131

Proliferative (follicular) phase
• During the 5th to 14th day of the menstrual cycle.
• Development of ovarian follicles and production of estrogen.
132

Proliferative (follicular) phase
• At the end of this phase:
– Thick endometrium with a diameter of 3 mm.
– Glands are straight tubules with narrow lumen
133

Secretory (Luteal) phase
• During the 15-28 days
• By progesterone produced from the corpus lutetium.
134

• Thick endometrium, 5mm in diameter by increased
accumulation of glandular secretion, edema and
increased stromal cells.
135

• Elongated and convoluted arteries reaching to the
superficial portions of the endometrium.
• Reduced contraction of the myocytes causing no
interference with implantation.
136

Proliferative, secretory, and premenstrual phases in the
uterus.
137

Menstrual phase
• During the 1-4th days of the menstrual cycle.
138

Menstrual phase
• Corpus luteim stops to function after serving for 14
days.
– Decreased estrogen and progesterone in the blood
causing: contraction of the coiled arteries leading to
necrosis and rupture of blood vessels.
– Detachment of stratum functionalis and gets sloughed
off.
139

Menstrual phase
• At the end, endometrium is formed only by stratum
basalis.
140

Correlation of ovarian and menstrual cycles
141

Correlation of ovarian and menstrual cycles
142

 Uterine glands secrete glycoproteins.
 Vessels dilate.
Endometrium at pregnancy and implantation
143

• Lamina propria swells and with decidual cells:
– Serve as embryothrophs.
– Protect uncontrolled invasion by the syncytiotrophoblast.
144

• As decidua basalis make maternal part of the placenta
• Fetal part is made by chroion frondosum
145

Histology of the Vagina
 The vagina is a fibromuscular tube that joins internal reproductive
organs to the external environment.
The vaginal wall consists of the following
 An inner mucosal layer has numerous transverse folds or rugae
and is lined with stratified squamous epithelium.
 An intermediate muscular layer is organized into two sometimes
indistinct, intermingling smooth muscle layers, an outer
longitudinal layer, and an inner circular layer.
147

 An outer adventitial layer is organized into an inner dense
connective tissue layer adjacent to the muscularis and an outer
loose connective tissue layer that blends with the adventitia of the
surrounding structures.
 The lumen of the vagina is lined by stratiﬁed squamous, non-
keratinized epithelium.
 Its surface is lubricated mainly by mucus produced by the cervical
glands.
 The greater and lesser vestibular glands located in the wall of the
vaginal vestibule produce additional mucus that lubricates the
vagina.
 Gland are not present in the wall of the vagina. 148

• Lamina propria
– Increased amount of elastic fibers, lymphocytes and
neutrophils
– High amount vascularization giving fluid exudates
during sexual arousal.
– No sensory innervations, although a few pain fibers
may be found.
– No glands.
149

Histology of the External Genitalia (vulva)
• Clitoris
– Made by two erectile bodies ending in glans clitoris
and prepuce.
– Lined by stratified squamous non-keratinized
epithelium.
152

• Labia minora
– Spongy connective tissue covered with skin.
– Lined by stratified squamous epithelium with a thin
layer of keratinized cells on the surface.
– Contains sebaceous and sweat glands on both
surface.
153

Inner surface of the labia majora.
154

• Labia majora
– Made by adipose tissue within layer of smooth
muscles covered with skin.
– Inner surface is similar with labia minora.
– Outer surface has coarse curly hairs.
– Has increased amount of sebaceous and sweat
glands on both surface.
155

• Greater vestibular glands (glandulae vestiularis
major, glands of Bartholins)
– One on each side
– Similar to bulbourethral glands
– Produce mucus
156

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