male reproductive system -...

Anhui Medical University


Male Reproductive System

Li Hong E-mail: [email protected] of Histology and Embryology




contentsGeneral description

Testis

Epididymis

Prostate



1. Consist of spermatogenic epithelium

2. The structure and functions of supporting cell

3. The structure and functions of Leydig cell

4. The structure of blood-testis barrier

Key points


Anhui Medical UniversityGeneral Description

TestesExcretory genital ducts:

epididymisductus deferensejaculatory ductsurethra

Accessory glands:prostateseminal vesiclesbulbourethral glands

Peniscolpulative organ


Anhui Medical UniversityTestisLocated in the scrotum

Ovoid or flattened

Being covered by testicular capsule:

tunica vaginalis and tunica albuginea



General structure

一 Testis

CapsuleTunica vaginalis：serosa

Tunica albuginea：thick, DCT• mediastinum testis: albuginea became thicker

at posterior portion• septum: thin septa extend radiately from

mediastinum testis to divided the parenchymainto lobule

LobuleTesticular interstitial tissue：LCT

between seminiferous tubule

Seminiferous tubule： highly coiled；30-70 cm long；150-250 mm in D



Tubuli recti



Each testis is composed of about 250pyramidal compartments called the testiculerLobules. Each lobule is occupied by 1-4seminiferous tubules enmeshed in a web ofLCT that is rich in blood and lymphaticVessels ,nerves and interstitial (Leydig) cell.



Testis


Anhui Medical University（一）Seminiferous Tubule

Spermatogenic epithelium

Spermato-

genic cell

Spermatogonium Primary spermatocytesSecondary spermatocyteSpermatidSperm

Supporting cell

Basement membrane

Tunica propria(myoid cell)


Anhui Medical UniversitySeminiferous tubules

Supporting or Sertoli cells

Spermatogenic cells

Basement membrane

Tunica propria and myoid cell (3-5 layers )

Germinal or seminiferous epithelium



1、spermatogenic cell

They are arranged in 4-8 layers since puberty. The cells replicate and migrate from the basal region of the seminiferous tubule to lumen as they mature.

1）Spermatogonium

(a primitive germ cell)

2）Primary spermatocyte

3）Secondary spermatocyte

4）Spermatid

5）Sperm (spermatozoa)



Adjacent to the basal membrane

Round or ellipsoid, small (10-12 µm)

1）Spermatogonium



1）SpermatogoniumStructure：Is a relatively small cell, about 12micrometer in diameter; round nucleus, deepstained by HE staining; situated next to thebasement membrane


Anhui Medical UniversityClassification ：

type A:dark typeA(Ad):ovoid,deep-stained,nucleus,stem cellPale type A(Ap)：ovoid, pale-stained,nucleus, differentiate into type B.

type B：round Nucleus, chromatin granules are distributedunder nucleus membrane, division and differentiate into primaryspermatocyte A

p B

Ad



Proliferation and differentiation of

Spermatogonium

Seminiferous tubules

(stem cell)


Anhui Medical University2) Primary spermatocyteThe primary spermatocyte has 46 (44+XY) chromosomes

and 4n amount of DNA soon after their formation, thesecells enter the prophase of the first meiotic divition. Since theprophase of this division takes about 22 days, the majority ofspermatocytes seen in sections will be in this phase. Fromthis first meiotic divisionarise smaller cells calledsecondary spermatocytes.

Structure ： roundcell, become largest, 18micrometer. large andround nucleus.



Primary spermatocyte



46 chromosomes (44+XX or XY) and 4n DNA (tetraploid)First meiosisLong prophase (up to 22 days)Frequently visible




3）Secondary spermatocyte

Nearer the lumen. The secondary spermatocyte has 23 Xor 23 y chromosomes and 2n amount of DNA.

Through secondary meiosis, a cell divides into twospermatids.

The secondary spermatocytes are difficult to observe insections because they are short-lived cells that remain ininterphase very brieflyand quickly enter intothe second meioticdivision.

Structure: Round cell, 12 micrometer in diameter. Round and deeper stained nucleus,



Secondary spermatocyte

By second meiotic division without prior duplication

of DNA, resulting in haploid spermatids


Anhui Medical University4） Spermatid

Structure：smallest cell, 8 micrometer

located at innerest layerThe spermatid has 23 X or 23

y chromosomes and 1n amount of DNA.

Through spermiogenesis: spermatid transform into sperm



Spermatid


Anhui Medical University5）SpermStructure ： Head：pear-shaped, flattened,

nucleus and acrosome Tail：flagellum

The axial core of whole tail iscalled axoneme which is consists of9+2 microtubules and surroundedby the outer dense fibers arrangedin longitudinal.Tail compose of 4 parts:

1) neck: a pair centriole2) middle segment：mitochondria sheath3) principal segment：fiber sheath4) end segment：only axoneme



Testis HE ×100

Testis HE ×400



It is characterised by the following events：

(1) condensation and elongation of Nucleus

(2) formation of the acrosome

－cover the anterior and lateral portion of N

－contain hydrolytic enzymes for fertilization

(3) formation of flagellum: for motility

(4) formation of mitochondria sheath

(5) discharge of useless organelle and cytoplasm

Spermiogenesisspermatid become into sperm



Spermiogenesis


Anhui Medical UniversitySpermatogenesis

Spermatogonium become into sperm

Sperm

Spermatogonium

Spermatid

Secondary spermatocyte




Proliferation and differentiation of

Spermatogonium

Seminiferous tubules

(stem cell)



Light Microscope : sperm


Anhui Medical UniversityScanning Electron Microscope : sperm


Anhui Medical University2 Supporting cell

Structure:

1）LM:－columnar or pyramidal cell－rest on basal lamina－extending into lumen－no clear boundary－elongated nucleus: triangular, ovoid, paler-

stained, with prominent nucleolus



2）EM

－rich SER, some RER,Golgi complex

－mitochondria , lysosome

－glycogen, lipid droplet

－tight junction



3）Functions

① . support, protect and nutrition,

②. secrete androgen-binding protein (ABP)

Function of ABP: bind to androgen, maintain the level of androgen concentration of lumen

③. phagocytose spermiogenic residual bodies

④. constitute the main parts of blood-testis barrier



Components:

Endothelium

Basal lamina of endotheliumConnective tissueBasal lamina of seminiferous tubuleTight junction of supporting cell

Functions:Protect the seminiferous cells from auto-immune

reaction, resistant to most harmful factors.

3 blood-testis barrier



（二） Interstitial tissue of testisLoose Connective Tissue Interstitial Cells (Leydig cell)



LM EM

Distribution of leydig cell: in groups

Structure：LM: －large, polygonal-shaped cell, with round nucleus

－acidophilic cytoplasmEM: they have the features of steroid-secreting cell



Secreting androgen which is essential for

Proliferation and differentiation of germ celll

The proper maintenance of the genital ducts and accessory glands

Development and maintenance of male second sex characteristics

Function of leydig Cells:


Anhui Medical University二 Epididymidis

→Epididymal duct.

1 Structure

Head→Efferent duct

Body

Tail


Anhui Medical University1）Efferent duct:

Scallop-like

Extending from the rete testis, forming the head of the epididymis

Tall columnar cells, ciliated: Secrete some fluid

Short columnar cells, nonciliated, numerous microvilli: Absorption of fluid and granulated matter


Anhui Medical University2）Epididymal duct:

4-6 m in length, 0.4 mm in diameter Pseudostratified columnar epithelium

Pricipal cell: Tall in the head, low columnar in the tail, with long microvilli

Basal cell: Small, round and pale-staining, located in the base of the epithelium

Basal cell

Pricipal cell



Absorption of fluid that leaves the testis

Secretion of glycerylphosphorycholine, sialic acid, glycoproteins, steroids

Promoting functional maturation of the sperm

Storing mature sperm, in the tail

Forcing the sperm into the ductus deferens by the contraction of smooth muscle

Function of Epididymal duct


Anhui Medical University三、Ductus deferensStructure：

Thick wall, narrow lumenmucosa, muscularis and adventitia

1) Mucosa: similar epithelium to that of the epididymal ductwith long microvilli in the tall columnar cell.



2) Muscularis: three layers Inner: longitudinalmiddle: circular outer: longitudinal

The powerful contraction rapidlytransports the sperm through the ductus deferens during ejaculation

3) Adventitia



Structure

四 Prostate

Function: secrete prostatic fluidThe semen is composed of sperm, secretory fluid of genital

ducts and accessory glands

The prostate is the largest accessory sex gland, with a weight of approximately 20 gram. Consisting of 30-50 compound tubuloalveolar glands.

Secretory portion：1）prostatic epithelium2）prostatic concretions are

observed in the lumen

Interstitial tissue ：elastic fiber and smooth muscle in rich


Anhui Medical UniversityProstate

Prostatic concretion

(eosinophilic body)

Smooth muscle

Prostatic epithelium



1. What is spermatogenic epithelium consist of ?

2. What are the main functions of supporting cell ?

3. Describe the structure and functions of Leydig cell.

4. Describe the structure and functions of blood-testis barrier.

Questions

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male reproductive system -...

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