Histology Of Male Reproduction Lecture 12 Flashcards
What does the parenchyma of the Testes consist of?
Testes Parenchyma Seminiferous tubules (Seminiferous epithelium) Interstitium: Interstitial cells ( Leydig cells) Intratesticular duct
What are the excurrent ducts?
Excurrent ducts (see DLA) 1. Efferent ducts 2. Duct of the Epididymis 3. Ductus deferens 4. Ejaculatory ducts
What are the accessory glands of the male reproductive system?
Accessory glands
Seminal vesicles
Prostate gland
Bulbourethral glands
What are the penis erectile tissues?
Corpus cavernosum
Corpus spongiosum
What are the parts of the urethra?
Urethra
Prostatic
Membranous
Penile (spongy)
What do the Testes develop from?
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
Summarize testicular trans abdominal descent
- Retroperitoneal
- Through inguinal canal
- To scrotum
• Processus vaginalis
• Evagination of peritoneal cavity and membrane
• Forms the tunica vaginalis
Why Testes are located outside the body?
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
Whaat are the tubes of the Testes ?
Seminiferous tubules → straight tubule → rete testis “ in the mediastinum testis” → efferent ductules → epididymis.
Whaat are the tubes of the Testes ?
Seminiferous tubules → straight tubule → rete testis “ in the mediastinum testis” → efferent ductules → epididymis.
Describe the structure of the testicular lobes
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 testisSummarize spermatogenesis
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)What are the functions of seminiferous epithelium?
Seminiferous Epithelium Spermatogenic cells Spermatogonia = Oval nuclei Primary spermatocytes = largest and most abundant. Secondary spermatocytes = rarely seen. Spermatids = Small oval shape Spermatozoa = Elongated
Describe the structure of spermatozoa
Spermatozoa Head Acrosomal cap→ contain acrosomal enzymes→ (Hyaluronidase, Neuraminidase) Tail (Flagellum) 1. Neck 2. Middle piece “Mitochondria” 3. Principal piece 4. End piece
What are Sertoli cells?
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)
What is cryptorchidism?
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
Describe the histopathology of cryptorchidism
Histopathology: Thickened basement membrane Narrow seminiferous tubule Most tubules have only Sertoli cells and no spermatogonia
Describe the structure of leydig cells
Interstitial cells (located in spaces between adjacent seminiferous tubules) • Large, eosinophilic cells with small, round nucleus and numerous lipid droplets
What is the function of leydig cells?
Function (Secrete testosterone):
• Embryo testis development
• Puberty (Spermatogenesis, accessory gland secretion, secondary sex characteristics)
Describe the hormonal control of the Testes
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
What are the Two general types of testicular tumors?
Germ cell (95% in post-pubertal males), malignant
Sex cord( uncommon, benign)
What are the types of sex cord tumors?
Sertoli cells
Leydig cells- typically secrete androgens. May secrete androgens & estrogens or even corticosteroids in some cases
What are the types of germ cell tumors?
Seminoma
Non-seminoma
What are the types of Non seminoma tumors?
- Yolk sac: below 3 years
- Embryonic carcinoma
- Teratoma
- Choriocarcinoma
What are the types of Seminoma tumors?
- Classical:
- 50% germ cell tumors
- 30-45 years
- Malignant—> lymphatic spread
- Spermatocyte:
- rare, men above 65. Yrs
Describe the macro type of classical seminoma
Large, round, polyhedral with distinct membrane
Creamy white & homogenous
Describe the micro type of classical seminoma
Sheets of uniform polygonal cells with distinct cells borders, clear cytoplasm, round nuclei, prominent nucleoli
-Poorly divided lobules with fibrous septa & lymphocyte infiltration
Explain the functions of seminal vesicles
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
Describe the seminal vesicles structure
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
Describe the mucosa of the seminal vesicle
Mucosa :
Pseudostratified epithelium
Columnar cells → secretory profiles
Basal cells (arrows in H&E x500)
Describe the structure of the prostate
Prostate
Single gland inferior to bladder
Typically the size of a golf ball or walnut
Surrounds the prostatic urethra and ejaculatory duct
What are the functions of the prostate?
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
Describe the histology of the prostate gland
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 amylaceaWhat are the histological zones of the prostate gland?
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 .
Explain benign prostatic hyperplasia
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 80Describe adenocarcinoma of prostate
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
Describe the bulbourethral glands
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
Describe the anatomy and histology of the bulbourethral glands
Located in urogenital diaphragm
Compound tubuloalveolar glands
Ducts merge & empty into penile urethra
Glandular epithelium
Simple columnar epithelium
Clear mucus secretion
Preseminal fluid
