Histology Of Male Reproduction Lecture 12

Question 1

What does the parenchyma of the Testes consist of?

Answer 1

Testes
 Parenchyma
 Seminiferous tubules
(Seminiferous epithelium)
 Interstitium: Interstitial cells ( Leydig cells)
 Intratesticular duct

Question 2

What are the excurrent ducts?

Answer 2

Excurrent ducts (see
DLA)
1. Efferent ducts
2. Duct of the
Epididymis
3. Ductus deferens
4. Ejaculatory ducts

Question 3

What are the accessory glands of the male reproductive system?

Answer 3

Accessory glands
 Seminal vesicles
 Prostate gland
 Bulbourethral glands

Question 4

What are the penis erectile tissues?

Answer 4

Corpus cavernosum

Corpus spongiosum

Question 5

What are the parts of the urethra?

Answer 5

Urethra
 Prostatic
 Membranous
 Penile (spongy)

Question 6

What do the Testes develop from?

Answer 6

Testes develop from:
 Intermediate mesoderm→ Leydig & and myoid cells
 Coelomic mesoderm (mesothelium) → Sertoli cells
 Germ cells→ from umbilical vesicle (yolk sac)
The testes then descends

Question 7

Summarize testicular trans abdominal descent

Answer 7

1. Retroperitoneal
2. Through inguinal canal
3. To scrotum
   • Processus vaginalis
   • Evagination of peritoneal cavity and membrane
   • Forms the tunica vaginalis

Question 8

Why Testes are located outside the body?

Answer 8

Why testes are located outside the body?
Structure (from outside in)
1. Tunicavaginalis:(peritoneum)
2. Tunicaalbuginea:Denseirregular connective tissue capsule, with Inner loose connective tissue Tunica Vasculosa (Blood vessels).
3.Testicular Lobules
Each lobule contains 1-4 seminiferous tubules

Question 9

Whaat are the tubes of the Testes ?

Answer 9

Seminiferous tubules → straight tubule → rete testis “ in the mediastinum testis” → efferent ductules → epididymis.

Question 9

Whaat are the tubes of the Testes ?

Answer 9

Seminiferous tubules → straight tubule → rete testis “ in the mediastinum testis” → efferent ductules → epididymis.

Question 10

Describe the structure of the testicular lobes

Answer 10

Structure of testicular lobes
1.Seminiferous tubules (ST)
 External layer (lamina propria)
       -3-5 layers of contractile myoid cells (M)→Peristaltic contraction
- Lined by seminiferous epithelium 
 Spermatogenic cells
 Sertoli cells
2. Straight tubules
3. Stroma: Interstitial (Leydig) cells
(IC)
4. Rete testis

Question 11

Summarize spermatogenesis

Answer 11

Spermatogenesis
Spermatogonial Phase: Mitosis Spermatogonia (2n,2d)
 Type A dark = reserve stem cells.  Type A pale = renewing stem cells.
 Type B. Spermatocyte phase: Meiosis
2. Spermatocyte phase: meiosis
 Primary spermatocyte (2n, 4d) 
     Undergoes Meiosis I
 Secondary spermatocyte (1n, 2d)
    undergoes Meiosis II 
3. Spermatid phase “Spermiogenesis”:
(remodeling & maturation)
Spermatid (1n, 1d)→ spermatozoa (1n, 1d)

Question 12

What are the functions of seminiferous epithelium?

Answer 12

Seminiferous Epithelium
Spermatogenic cells
 Spermatogonia = Oval nuclei
 Primary spermatocytes = largest and most abundant.
 Secondary spermatocytes = rarely seen.
 Spermatids = Small oval shape
 Spermatozoa = Elongated

Question 13

Describe the structure of spermatozoa

Answer 13

Spermatozoa
 Head
Acrosomal cap→ contain acrosomal enzymes→ (Hyaluronidase, Neuraminidase)
 Tail (Flagellum)
1. Neck
2. Middle piece “Mitochondria”
3. Principal piece
4. End piece

Question 14

What are Sertoli cells?

Answer 14

Columnar cells with elongated, pale nuclei and prominent nucleolus
 Sertoli cells are supporting (sustentacular) cells
 Form the blood-testis barrier
 Secrete inhibin
Hormone that inhibits FSH secretion
 Secrete androgen-binding protein Binds testosterone to keep
concentration high.
 Secrete müllerian-inhibiting substance (MIS)

Question 15

What is cryptorchidism?

Answer 15

Condition when testes do not descend into the scrotum
 1% full-term infants
 30% premature infants
 Most (80%) will descend spontaneously during the first year of life
 Untreated & bilateral results in sterility
 30-50x greater risk of testicular cancer

Question 16

Describe the histopathology of cryptorchidism

Answer 16

Histopathology:
 Thickened basement
membrane
 Narrow seminiferous tubule
 Most tubules have only Sertoli cells and no spermatogonia

Question 17

Describe the structure of leydig cells

Answer 17

Interstitial cells (located in spaces between adjacent seminiferous tubules)
• Large, eosinophilic cells with small, round nucleus and numerous lipid droplets

Question 18

What is the function of leydig cells?

Answer 18

Function (Secrete testosterone):
• Embryo testis development
• Puberty (Spermatogenesis, accessory gland secretion, secondary sex characteristics)

Question 19

Describe the hormonal control of the Testes

Answer 19

Hypothalamus
 Gonadotropin-releasing hormone (GnRH)

 Anterior Pituitary
 Luteinizing hormone (LH)
 StimulatesLeydigcellstosecretetestosterone
 Follicle-stimulating hormone (FSH)
 Stimulates Sertoli cells to secrete androgen-binding protein
 Leydig cells
 Testosterone
 Sertoli cells
 Androgen-binding protein (ABP)
 Bindstestosteronetokeepconcentrationhigh
 Inhibin
 HormonethatinhibitsFSHsecretion

Question 20

What are the Two general types of testicular tumors?

Answer 20

Germ cell (95% in post-pubertal males), malignant

Sex cord( uncommon, benign)

Question 21

What are the types of sex cord tumors?

Answer 21

Sertoli cells

Leydig cells- typically secrete androgens. May secrete androgens & estrogens or even corticosteroids in some cases

Question 22

What are the types of germ cell tumors?

Answer 22

Seminoma

Non-seminoma

Question 23

What are the types of Non seminoma tumors?

Answer 23

1. Yolk sac: below 3 years
2. Embryonic carcinoma
3. Teratoma
4. Choriocarcinoma

Question 24

What are the types of Seminoma tumors?

Answer 24

- Classical: - 50% germ cell tumors - 30-45 years - Malignant—> lymphatic spread - Spermatocyte: - rare, men above 65. Yrs

Question 25

Describe the macro type of classical seminoma

Answer 25

Large, round, polyhedral with distinct membrane |  Creamy white & homogenous

Question 26

Describe the micro type of classical seminoma

Answer 26

Sheets of uniform polygonal cells with distinct cells borders, clear cytoplasm, round nuclei, prominent nucleoli -Poorly divided lobules with fibrous septa & lymphocyte infiltration

Question 27

Explain the functions of seminal vesicles

Answer 27

Seminal vesicles  Paired glands posterior to bladder  Duct joins ampulla of ductus deferens to form ejaculatory duct  Secrete a whitish yellow, alkaline, viscous fluid  Fructose  ATP production by sperm  Prostaglandins  Produce about 60% of volume of semen

Question 28

Describe the seminal vesicles structure

Answer 28

Fibrous coat  Smooth muscle  Indistinct inner circular layer & outer longitudinal layer  Mucosa forms numerous arches/folds (arrows in H&E x20/x30)  However, there is only one lumen which is tortuous & tubular

Question 29

Describe the mucosa of the seminal vesicle

Answer 29

Mucosa :  Pseudostratified epithelium  Columnar cells → secretory profiles  Basal cells (arrows in H&E x500)

Question 30

Describe the structure of the prostate

Answer 30

Prostate  Single gland inferior to bladder  Typically the size of a golf ball or walnut  Surrounds the prostatic urethra and ejaculatory duct

Question 31

What are the functions of the prostate?

Answer 31

``` Secretes a clear, slightly alkaline fluid into the prostatic urethra  Citric acid  (a nutrient for sperm)  Prostate-specific antigen (PSA)  Serine protease  Biomarker  Prostatic acid phosphatase (PAP)  Regulates cell growth & metabolism  Seminal plasmin  Antibiotic  Fibrolysin  Liquefies semen  Produces about 25% of volume of semen ``` Testosterone converted to dihydrotestosterone (DHT)  5α-reductase  DHT stimulates growth of epithelium & fibromuscular stroma

Question 32

Describe the histology of the prostate gland

Answer 32

``` 30-50 tubuloalveolar glands  3 concentric layers 1. Inner mucosal layer  Secretedirectlyintourethra 2. Intermediate submucosal layer  Secreteviaducts 3. Peripheral layer contains main glands  Secrete. via ducts  Glandular epithelium  Simple columnar to pseudostratified  Prostatic concretions  Corpora amylacea ```

Question 33

What are the histological zones of the prostate gland?

Answer 33

Glandular tissue organized in histological zones: 1.Central zone: Surrounds ejaculatory ducts 25% glandular tissue 2.Peripheral zone: Surrounds central zone Occupies posterior & lateral region of the gland 70% glandular tissue Clinical correlation: Most prostatic carcinomas arise from peripheral zone 3.Transition zone Surrounds prostatic urethra 5% glandular tissue (Mucosal glands) Clinical correlation: Benign prostatic hyperplasia (BPH) Parenchyma hyperplasia forms nodules Anterior fibromuscular stroma Dense irregular connective tissue w/ smooth muscle **Note: Histological zones are different than anatomical zones. Pawlina text also lists a periurethral zone .**

Question 34

Explain benign prostatic hyperplasia

Answer 34

``` Proliferation of glandular epithelium  Hyperplasia  DHT acts on epithelium & stroma  Results in formation of numerous nodules  Compression of the prostatic urethra  Weak urination  Difficulty starting & stopping  Urge or feeling to urinate  Enlarged prostate gland  Relatively common in men by age 80 ```

Question 35

Describe adenocarcinoma of prostate

Answer 35

``` Most common form of cancer in men  Typically affects men over 50 years  May spread via lymphatics Macro  Arises in peripheral zone in ~70% of cases ``` Micro  Well-defined glandular pattern  Small, round glands crowded Robbins between larger glands 9th  Dark cytoplasm, enlarged nuclei, prominent nucleoli  Lack a basal layer and overcrowded

Question 36

Describe the bulbourethral glands

Answer 36

Bulbourethral glands (Cowper’s glands)  Paired glands inferior to prostate on either side of the membranous urethra  Ducts open into the penile (spongy) urethra  Secrete clear, mucus-like fluid into the penile urethra  Preseminal fluid

Question 37

Describe the anatomy and histology of the bulbourethral glands

Answer 37

Located in urogenital diaphragm Compound tubuloalveolar glands Ducts merge & empty into penile urethra  Glandular epithelium  Simple columnar epithelium  Clear mucus secretion  Preseminal fluid