Cui Dongmei. Atlas of Histology: with functional and clinical correlations. 1st ed

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Figure 18-14C Rete Testis

Figure 18-15A,B Ductuli Efferentes

Figure 18-15C Clinical Correlation: Testis Seminoma

Extratesticular Genital Ducts

Figure 18-16 Ductus Epididymis

Figure 18-17A,B Epithelium of the Ductus Epididymis

Figure 18-18A Ductus Deferens, Spermatic Cord

Figure 18-18B,C Ductus Deferens

Figure 18-19A,B Ejaculatory Duct, Prostate Gland

Figure 18-19C Epithelium of the Prostatic Urethra

Accessory Genital Glands

Figure 18-20A,B Prostate Gland

Figure 18-20C Clinical Correlation: Prostate Cancer

Figure 18-21A,B Seminal Vesicles

Figure 18-21C Seminal Vesicle with Seminal Fluid

Penis

Figure 18-22 Overview of the Penis

Synopsis 18-3 Clinical and Pathological Terms for the Male Reproductive System

Introduction and Key Concepts for the

Male Reproductive System

The male reproductive system is composed of (1) a pair of testes

where spermatogenesis takes place; (2) a series of genital ducts

that include intratesticular genital ducts and extratesticular

genital ducts (which function to carry spermatozoa from the

testes to their destination); (3) three major accessory genital

glands: the prostate gland, seminal vesicles, and bulbourethral

glands; and (4) the penis, which is the male copulatory

organ. The main functions of the male reproductive system

include production of spermatozoa, fertilization of the

ovum in the female reproductive tract, production of sex

hormones (testosterone) to develop and maintain secondary

male sex characteristics, and performance of sexual activity

(copulation).

Testis

The testis consists of numerous convoluted seminiferous

tubules that are lined by seminiferous epithelium supported

by a basement membrane. The seminiferous epithelium

hosts various stages of spermatogenic cells (spermatogonia,

spermatocytes, and spermatids), which are protected,

nourished, and supported by Sertoli cells. The Sertoli cells also

produce testicular ﬂ uid, anti-Müllerian hormone, androgen-

binding protein (ABP), etc. Between the seminiferous tubules,

there is loose connective tissue that contains a special type of

cells called the interstitial cells of Leydig. These cells mainly

produce testosterone hormone that promotes spermatogenesis

and the development of male sexual organs as well as maintains

secondary male sexual characteristics. The testis is covered by

the tunica albuginea (capsule), tunica vaginalis (mesothelial

sac), and an outer layer of wrinkled thin skin, the scrotum.

Spermatogenesis takes place in the seminiferous epithelium of

the tubules (see Figs. 18-9 to 18-13B).

Intratesticular Genital Ducts

The intratesticular genital ducts are located within the testis,

including the tubuli recti, rete testis, and ductuli efferentes.

1. Tubuli recti: These are short, straight tubules lined by

simple cuboidal epithelium. They carry the newly produced

spermatozoa in testicular ﬂ uid from the seminiferous tubules to

the rete testis in the mediastinum of the testis (Fig. 18-14B).

2. Rete testis: This is a maze of anastomosing tubules with an

irregular lumen and is lined by simple cuboidal epithelium

(Fig. 18-14C). This network of interconnecting tubules

conducts the sperm atozoa and testicular ﬂ uid into the

ductuli efferentes.

3. Ductuli efferentes: These convoluted tubules are alternatively

lined by two cell types: nonciliated cuboidal cells and ciliated

columnar cells. The ductuli efferentes absorb some testicular

ﬂ uid and move the spermatozoa to the head of the epididymis

(Fig. 18-15A,B).

Extratesticular Genital Ducts

The extratesticular genital ducts located outside the testis

include the ductus epididymis, ductus deferens, ejaculatory

ducts, and urethra. These ducts are paired tubules except the

urethra, which is a single tubule.

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1. Ductus epididymis: Each ductus epididymis is a highly

convoluted tube (about 6 m long) that has three regions:

head, body, and tail (Figs. 18-16 to 18-17B). They are lined

by pseudostratiﬁ ed columnar epithelium with long stereo-

cilia that absorb large volumes of testicular ﬂ uid from the

lumen and secrete a variety of substances, including glycero-

phosphocholine, which inhibits capacitation of spermatozoa

from occurring in the male reproductive tract. The tail of the

epididymis is the region where spermatozoa mature and are

stored.

2. Ductus deferens: Each ductus deferens is a long tube that

courses partly within a spermatic cord. Its proximal end

connects with the tail of the epididymis. The distal portion

becomes enlarged and is known as the ampulla. After its

junction with the duct of the seminal vesicle, the ductus

deferens continues its course to form the ejaculatory duct.

The ductus deferens is lined by pseudostratiﬁ ed columnar

epithelium and surrounded by a thick muscularis consisting

of three layers of smooth muscle (Fig. 18-18A–C).

3. Ejaculatory ducts: The two ejaculatory ducts are surrounded

by the prostate gland (Fig. 18-19A,B). They are straight

tubes, lined by pseudostratiﬁ ed columnar and simple

columnar epithelium. The ejaculatory ducts open into the

prostatic urethra at the colliculus seminalis. The colliculus

seminalis is a median elevation of the verumontanum, the

portion of the male prostatic urethra where the ducts open.

4. Urethra: The urethra is a long tube (about 20 cm) lined by

various types of epithelium. It is a common passage shared by

the urinary system and reproductive system in the male. It can

be divided into three regions: the prostatic, the membranous,

and the spongy (penile) urethra. The prostatic urethra, lined

by transitional epithelium, is connected with the bladder at

its proximal end and passes through the prostate gland. The

prostatic urethra is wider than other parts of the urethra and

has two ejaculatory ducts opening into the urethra. The short

membranous urethra is lined by pseudostratiﬁ ed columnar

epithelium; it is the intermediate and narrowest part of the

urethra. The membranous urethra connects the prostatic

urethra to the spongy urethra. The spongy urethra, also called

the penile urethra, is lined by stratiﬁ

ed columnar epithelium.

It passes through the penis and is the longest segment of the

urethra (Fig. 18-22).

Accessory Genital Glands

The accessory genital glands are exocrine glands that include

the prostate gland, paired seminal vesicles, and bulbourethral

glands. (1) The prostate gland is a collection of about 40 small

tubuloalveolar glands lined by simple columnar epithelium and

supported by a connective tissue stroma. Prostatic secretions

contain proteolytic enzymes, acid phosphatase, citric acid,

ﬁ brinolysin, and lipids (Fig. 18-20A,B). (2) Each seminal

vesicle has a single convoluted tube with a branched and folded

mucosa lined by pseudostratiﬁ ed columnar epithelium. The

epithelium is supported by a thin connective tissue layer that

is surrounded by two layers of smooth muscle (muscularis).

The seminal vesicle produces seminal ﬂ uid containing fructose,

prostaglandins, ﬂ avins, phosphorylcholine, vitamin C, and

proteins (Fig. 18-21A–C). Semen is a mixture of seminal ﬂ uid,

prostatic secretion, spermatozoa, and testicular ﬂ uid. (3) The

bulbourethral glands are a small pair of glands lined by simple

columnar epithelium. They produce preejaculate (preseminal)

ﬂ uid that lubricates the urethra before ejaculation.

Penis

The penis is an external genital organ that consists of three

cylinders of erectile tissue, including the corpora cavernosa

(two) and the corpus spongiosum (one). The corpus spongiosum

contains the urethra in its center. The penis has a unique blood

supply (dorsal arteries, deep arteries, and helicine arteries)

and drainage (superﬁ cial veins, arteriovenous shunts) that are

correlated with its erection (Fig. 18-22).

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Seminal

vesicle

Prostate

gland

Bulbourethral

gland

Bladder

Sacral

vertebra

Rectum

Ejaculatory

duct

Ductus

deferens

Corpus

cavernosum

Penile

urethra

Urethra

Urethral

orifice

Glans

penis

Penis

Epididymis

Tes t is

Scrotum

Figure 18-1. Overview of the male reproductive system.

The male reproductive system includes the testes, genital ducts, accessory genital glands, and penis. There are two testes where sper-

matogenesis takes place and sex hormones (testosterone) are produced. The genital ducts include intratesticular genital ducts and

extratesticular genital ducts. The intratesticular genital ducts comprise the tubuli recti, rete testis, and ductuli efferentes, which are

located inside of the testis. The extratesticular genital ducts comprise the ductus epididymis, ductus deferens, ejaculatory duct, and

urethra. The accessory genital glands include three major glands: the seminal vesicles, prostate gland, and bulbourethral glands. Two

ejaculatory ducts meet with the prostatic urethra before it continues its course through the urogenital diaphragm as the membranous

urethra and then through the penis as the penile urethra. The penis is composed of three cylinders of spongy erectile tissue including

the two corpora cavernosa and the corpus spongiosum (containing the urethra).

Structures of the Male Reproductive System

I. Testes

A. Testicular tunicate

1. Tunica vaginalis

2. Tunica albuginea

3. Tunica vasculosa

4. Medastinum testis

5. Special cells (interstitial cells of Leydig)

B. Seminiferous tubules

1. Spermatogenic cells

2. Sertoli cells

II. Genital ducts

A. Intratesticular genital ducts

1. Tubuli recti

2. Rete testis

3. Ductuli efferentes

B. Extratesticular genital ducts

1. Ductus epididymis

2. Ductus (vas) deferens with spermatic cord

3. Ejaculatory ducts

4. Urethra (prostatic, membranous, and spongy/penile

urethra)

III. Accessory genital glands

A. Prostate gland

B. Seminal vesicles

C. Bulbourethral glands

IV. Penis

A. Tunica albuginea

B. Corpus cavernosum

C. Corpus spongiosum and spongy/penile urethra

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Fig. 18-18A,B,C

Fig. 18-3A to

Fig. 18-13B

Fig. 18-14A to

Fig. 18-15B

Fig. 18-22

Fig. 18-21A,B,C

Fig. 18-20A,B,C

Fig. 18-19A,B,

Figure 18-2. Orientation of detailed male reproductive system illustrations.

Structures of the Urinary System with Figure Numbers

Testis:

Seminiferous tubules

Figure 18-3A

Figure 18-3B

Figure 18-3C

Figure 18-4A

Figure 18-4B

Figure 18-5

Figure 18-6A

Figure 18-6B

Figure 18-7

Figure 18-8

Spermatogenesis

Figure 18-9

Figure 18-10

Figure 18-11A,B

Figure 18-12A,B

Figure 18-13A,B

Intratesticular genital ducts:

Tubuli recti

Figure 18-14A

Figure 18-14B

Rete testis

Figure 18-14C

Ductuli efferentes

Figure 18-15A

Figure 18-15B

Figure 18-15C

Extratesticular genital ducts:

Ductus epididymis

Figure 18-16

Figure 18-17A

Figure 18-17B

Ductus deferens and spermatic cord

Figure 18-18A

Figure 18-18B

Figure 18-18C

Ejaculatory ducts

Figure 18-19A

Figure 18-19B

Prostatic urethra

Figure 18-19C

Accessory genital glands:

Prostate gland

Figure 18-20A

Figure 18-20B

Figure 18-20C

Seminal vesicles

Figure 18-21A

Figure 18-21B

Figure 18-21C

Penis:

Figure 18-22

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Ductus

deferens

Ductus

epididymis

(tail)

Ductus

epididymis

(body)

Medastinum

Ductus epididymis

(head)

Test i s

Ductuli

efferentes

Rete testis

Tubuli recti

Tunica vaginalis

Tunica albuginea

Septum

Seminiferous

tubule

Lumen of the

seminiferous tubules

Lumen of the

seminiferous tubules

Interstitial connective

tissue

Interstitial connective

tissue

Septum

Basement

membrane

Basement

membrane

Tubuli recti

Septum

Myoid

cells

Myoid

cells

Seminiferous

tubule

Seminiferous

tubule

Seminiferous

Semin

ifero

epithelium

ithe

Seminiferous

epithelium

Lumen

Fibroblast

Seminiferous

tubule

Seminiferous

tubule

Basement

membrane

Basement

membrane

Figure 18-3A. Overview of the testis.

Each testis is composed of many convoluted seminiferous

tubules. The anterior portion of the testis is covered by a closed

sac of peritoneum called the tunica vaginalis (mesothelial sac).

The tunica albuginea is a thick layer of capsule (dense connec-

tive tissue) that surrounds and divides the testis into small lob-

ules; the connective tissue continues at the posterior part and

becomes thicker and forms the vertically oriented connective

tissue mass called the mediastinum. The mediastinum contains

the rete testis, which consists of a labyrinth of small channels

that collect sperm from the tubuli recti. The ductus epididymis

is a single long, highly convoluted duct that receives sperm

from the ductuli efferentes. The epididymis is divided into

three parts: the head, body, and tail. The tail of the epididymis

connects with the ductus deferens. The testes play important

roles in the production of sperm and secretion of testosterone

(sex hormone).

Testis

Figure 18-3B. Seminiferous tubules of the testis. H&E,

122

Seminiferous tubules are the main functional components of

the testis. Each of the several hundred seminiferous tubules

in each testis is a highly coiled tubule lined by a stratiﬁ ed

germinal (seminiferous) epithelium containing various stages of

spermatogenic cells. The seminiferous epithelium is supported

by the basement membrane. Cross sections of some seminifer-

ous tubules and a connective tissue septum are shown here.

The tubuli recti (straight tubules) are located in the connec-

tive tissue septa. The connective tissue between neighboring

tubules, which contains small vessels and endocrine cells, is

called interstitial connective tissue.

Figure 18-3C. Seminiferous tubule. H&E, 281

This is an example of a single seminiferous tubule, consisting

of germinal epithelium and its basement membrane. The

seminiferous tubule is surrounded by a very thin connective

tissue containing a few ﬁ broblasts. Another type of cell, the

myoid cell, has the appearance of smooth muscle cells, with ﬂ at

and elongated nuclei. These cells surround the seminiferous

tubules and contract to help the movement of the testicu-

lar ﬂ uid in which the spermatozoa are suspended. Neigh-

boring seminiferous tubules are in close contact with one

another. The various stages of the spermatogenic cells include

spermatogonia, spermatocytes (primary and secondary), and

spermatids (early, intermediate, and late). They are present in six

different speciﬁ c combinations of cell types that deﬁ ne the st ages

of the cycle of the seminiferous epithelium (Figs. 18-11A

to 18-13B).

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Organ Systems

Spermatids

Spermatogonia

Primary

spermatocyte

Primary

spermatocyte

Interstitial cell

of Leydig

Interstitial cell

of Leydig

Intermediate

Early

Sertoli

cells

Sertoli

cells

Fibroblast

Late

Interstitial connective

tissue

Interstitial connective

tissue

Myoid

cell

Myoid

cell

Late spermatids

Early spermatids

Primary spermatocytes

Sertoli cell nuclei

Sertoli cells

Basement

membrane

Sertoli cells

Spermatogonium

Figure 18-4A. Cells in the seminiferous tubules. H&E, 458

There are two types of cells in the seminiferous tubules:

spermatogenic (germ) cells and supporting (Sertoli) cells. The

spermatogenic cells consist of

1. Spermatogonia: These cells have round or oval nuclei and

are located near the basement membrane. They can be sub-

divided into type A and type B cells. Type A cells are stem

cells that divide slowly and give rise to type B cells.

2. Spermatocytes: These derivatives of spermatogonia B cells

undergo meiosis. They move toward the lumen and can be

divided into primary (ﬁ rst meiotic division) and secondary

(second meiotic division) spermatocytes. Primary sperma-

tocytes in prophase are most commonly seen in sections.

Their large nuclei contain strands of condensed chromo-

somes. Secondary spermatocytes complete the second mei-

otic division very quickly, so they are rarely seen.

3. Spermatids: These cells have small interphase nuclei that

range from spherical to thin and elongated. They can be

classiﬁ ed as early, intermediate, or late spermatids, based

mainly on the appearance of the nucleus.

Figure 18-4B. Seminiferous epithelium. EM, 4,600

This low magniﬁ cation view shows almost the full thickness of the seminiferous epithelium. Sertoli cells are the nongerm cells that

organize the epithelium and divide it into two compartments, basal and adluminal (Fig. 18-12A). The only cell type in the basal com-

partment is the spermatogonium, which, like the Sertoli cells, contacts the basement membrane. This patch of epithelium appears to

be in stage one of the six stages (cell associations) of seminiferous epithelium. The adluminal compartment contains three cohorts of

cells, each at a different stage of spermatogenesis. The least advanced cells are primary spermatocytes in prophase of meiosis I. The

chromosomes of these diploid cells have begun condensing, and homologous pairs have aligned into synaptonemal complexes. Early

spermatids, which appear as small, undifferentiated cells, predominate in the middle and superﬁ cial regions of the epithelium. The third

and most advanced cell type here is the late spermatid. The heads of a few can be seen surrounded by the cytoplasm of a Sertoli cell.

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Nucleus of

early spermatid

Nucleus of

early spermatid

Nucleus of

early spermatid

Nucleus of

early spermatid

Centrioles

Nucleus of

early spermatid

Nucleus of

early spermatid

Golgi complex

Figure 18-5. Seminiferous epithelium, early spermatid. EM, 17,000

Completion of meiosis II by secondary spermatocytes produces spermatids. These are haploid cells that do not divide but undergo

spermiogenesis, that is, morphological differentiation into spermatozoa. The cells in this image are early spermatids that have not

yet acquired many of the specializations of spermatozoa. The interphase nucleus in the center is still spherical, and the chromatin is

not yet highly condensed. The Golgi complex, visible in the cell on the left, will be the site of development of the acrosomal vesicle

and, ultimately the acrosome, which will form a cap on one side of the nucleus. Note that the plane of section happens to pass

through the central cell’s centrosome with its pair of centrioles. One member of the pair will organize the development of the ﬂ agel-

lum with its axoneme of microtubules. The other centriole will participate in the ﬁ rst cleavage division if the spermatozoan fertilizes

a secondary oocyte. This spermatid is linked to its cohort spermatids by cytoplasmic bridges, although this is not evident in this

image. Like all cells engaged in spermatogenesis, spermatids are embedded in cytoplasmic processes of Sertoli cells.

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Organ Systems

Sertoli cell

Early

spermatid

Early

spermatid

Early

spermatid

Early

spermatid

Late

spermatid

Late

spermatid

Sertoli cells

Primary

spermatocyte

Primary

spermatocyte

Chromosomes in nucleus

of primary spermatocyte

Nucleolus of Sertoli cell

Nucleus of Sertoli cell

Cytoplasm of Sertoli cell

Basal lamina of

seminiferous epithelium

Sertoli cell

Tight junction

between sertoli cells

Tight junction

between sertoli cells

Figure 18-6A. Sertoli cells, seminiferous tubules.

H&E, 732; inset 1,603

Sertoli cells have pale oval or irregularly shaped nuclei,

and nucleoli are often present. They are irregular colum-

nar cells with many folded cytoplasmic processes form-

ing compartments for the spermatogenic cells. They

form tight junctions (zonulae occludentes) with the

neighboring Sertoli cells thereby providing a blood-

testis barrier to protect spermatogenic cells from being

harmed by autoimmune reactions. Sertoli cells con-

trol hormones, nutrients, and other substances pass-

ing through the compartments and maintain the ideal

environment for spermatogenesis. They play important

roles in supporting, protecting, and nourishing sper-

matogenic cells as well as in secreting testicular ﬂ uid

(rich in fructose) to help in transporting spermatozoa

out of the seminiferous tubules. They also secrete

ABP, anti-Müllerian hormone, and inhibin and activin

hormones.

Figure 18-6B. Sertoli cell and primary spermatocyte, seminiferous epithelium. EM, 7,900; inset (color) H&E, 1,005

Sertoli cells, the only somatic cells of the seminiferous epithelium, are dynamic cells with a long list of functions in support of

spermatogenesis. Their processes envelope and support the germ cells throughout the many stages of meiosis and spermiogenesis.

In this view, cytoplasmic extensions of the Sertoli cell (with its nucleus at the left edge) enshroud the primary spermatocyte that has

entered prophase of meiosis I and isolate it from the basal compartment so that it is no longer accessible to the immune system. Note

also the example of the junctional complexes (including tight junctions) that couple adjacent Sertoli cells and, thereby, establish a

controlled and specialized environment in support of the cells that are undergoing spermatogenesis. Other functions of Sertoli cells

are secretion of testicular ﬂ uid, concentration of androgens, and phagocytosis of the residual bodies jettisoned by late spermatids as

they complete spermiogenesis.

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353

Seminiferous

tubule

Seminiferous

tubule

Leydig

cells

Leydig

cells

Seminiferous

tubule

Seminiferous

tubule

Lipid vacuoles

of Leydig cell

Lipid vacuoles

of Leydig cell

Leydig cell

Fibroblast

Lumen of

capillary

Lumen of

capillary

Basement membrane

of the

seminiferous tubule

Basement membrane

of the

seminiferous tubule

Leydig

cells

Leydig

cells

Figure 18-7. Interstitial cells of Leydig. H&E, left 263; right

2,016; iron hematoxylin stain, 237

The interstitial cells of Leydig are located in the interstitial (connec-

tive) tissue near the blood capillaries and between the seminiferous

tubules. These cells have round nuclei and pale-stained cytoplasm with

lipid drops (lipid vacuoles) in the peripheral region of the cytoplasm,

which give them a bubbly appearance (like many steroid-producing

cells). These cells contain abundant smooth endoplasmic reticulum,

which contributes to steroid hormone production. The interstitial cells

of Leydig derive from the mesoderm and are usually large in size (about

20 μm in diameter) compared with other cells in the connective tissue.

They are the endocrine cells that produce the important male sex

hormone, testosterone. Testosterone plays important roles in develop-

ing and maintaining male sex characteristics, stimulating muscle and

bone growth, and increasing bone density. A small amount of testoster-

one is also produced by the adrenal glands and ovaries in the female.

SYNOPSIS 18-1 Functions of Sertoli Cells

Support ■ : Provide physical support and nutrition for the different stages of spermatogenic cells.

Protection

■ : Form blood-testis barrier by tight junctions between adjacent Sertoli cells that protect spermatogenic cells

from autoimmune destruction; also control hormones, nutrients, and other substances being transported in and out of the

seminiferous tubules.

Phagocytosis

■ : Remove residual bodies after excess cytoplasm is shed from the spermatids during maturation of the spermatozoa.

Secretion

■ : (1) Secrete and release fructose-rich ﬂ uids (testicular ﬂ uid) to help nourish and move sperm from the seminifer-

ous tubules to the epididymis; (2) secrete anti-Müllerian hormone to prevent oviducts from developing from the Müllerian

duct in the early stages of the male embryo; (3) secrete androgen-binding protein (ABP) to maintain the concentration of

testosterone in the seminiferous tubules, thereby promoting spermatogenesis; (4) secrete glial cell–derived neurotrophic

factor (GDNF) to promote survival and differentiation of the spermatids (GDNF is better known for promoting development

of neurons); and (5) produce inhibin and activin hormones to provide negative and positive feedback to the hypothalamus,

thereby regulating follicle-stimulating hormone (FSH) secretion by the pituitary gland.

SYNOPSIS 18-2 Functions of Testosterone

The interstitial cells of Leydig secrete testosterone, which is the major male sex hormone. Its functions include:

Promoting development of male sex organs in early fetal development.

■

Promoting male sexual characteristics, such as growth of beard and axillary hair, enlargement of the larynx, and deepening ■

the voice.

Increasing muscle growth, thickness of the skin, and sebaceous gland secretion.

■

Promoting bone growth and increasing bone density. ■

Increasing basal metabolism and physical energy. ■

Promoting spermatogenesis. ■

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Organ Systems

D. Cui

Interstitial (Leydig) cell

Hypothalamus

Inhibin (–)

Activin (+)

FSH (+)

)(gonadotrophs

LH (+)

()gonadotrophs

(–)

GnRH (+) LH

GnRH (+) FSH

Pituitary gland

Increases

concentration

of testosterone

Inhibin & activin

hormones

ABP

Sertoli cell

Sertoli cellSertoli cell

Sertoli cell

(+)

Inhibits female organ

development

Anti-Müllerian

hormone

Promotes

spermatogenesis

Supports development of

male sex organs and

maintains male sexual

characteristics;

promotes spermatogenesis

(+)

Testosterone

Figure 18-8. Hormone regulation involving the testicular cells (interstitial cells of Leydig and Sertoli cells). H&E, 1,005

The preoptic nucleus in the hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland

to produce and release luteinizing hormone (LH) and FSH. Secretion of testosterone by the interstitial cells of Leydig is stimulated

by the LH produced by the gonadotrophs in the adenohypophysis of the pituitary gland. An excessive level of testosterone sends

negative feedback to the hypothalamus to inhibit production of GnRH, resulting in decreased secretion of LH in the pituitary gland.

Sertoli cells that release ABP are stimulated by FSH, which stimulates production of the ABP. Sertoli cells also secrete anti-Müllerian

hormone as well as inhibin and activin hormones. The inhibin hormone suppresses and activin hormone stimulates the production

of GnRH, which inﬂ uences FSH production by the gonadotrophs in the adenohypophysis of the pituitary gland.

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