E2: Reproductive: Male Flashcards
Testes
Describe their embryonic development
- Testes develop in a retroperitoneal position attached to the gubernaculum (Dense Regular CT)
- Fusion of the peritoneum and the gubernaculum allows the vaginal process to form
- •(outpocketing of the parietal peritoneum)
- Testes are pulled through the inguinal canal by the regression of the gubernaculum.
- Closure of the vaginal process (Few weeks before or after birth)
- Remaining serous membrane wraps around the testis = tunica vaginalis
- •Visceral & parietal layers of mesothelium
Testes:
Describe the structure of the testes
- Spermatic cord:
* Pathway for nerves & blood vessels. - Tunica Vaginalis:
- Secretes Fluid to provide lubrication
- Location of potential Hydrocele*
- Tunica albuginea
- CT capsule
- Divides testis into lobules
- Lobules contain Seminiferous tubules
Seminiferous Tubules:
Describe the structure & Composition
SN tubules are Lined by Germinal Epithelium
- Spermatogenic cells:
- Spermatogonia (SG)
- Differentiating sperm cells
- Sertoli cells (SC):
- Nurse cells for developing Sperm
- Secrete hormones
Interstitium
- Fibroblasts
- Myoid Cells: Contractile
- Leydig cells (interstitial cells)
- Secrete Testosterone
- Capillaries
Myoid cell contraction & Sertoli exocrine secretion constantly pushing sperm into Epididymis
Seminiferous Tubules:
Describe the process of Spermatogonia
Spermatogonia:
- Undifferentiated germ cells At the base
Development (2-3 months)
-
Spermatogenesis
* Spermatogonia to spermatid -
Spermiogenesis
* Differentiation to mature sperm (spermatozoa)
Spermatogonia – at the base
Spermatids –elongated nuclei – minimal flagellum
Sperm (spermatozoa) – flagella/acrosome
Spermiogenesis
Describe the appearance of Spermiogensis in the SN
What are the components of the mature sperm cell?
Components of Sperm Cells:
Flagellum:
•Necessary for movement from vagina to Fallopian tubes
Mitochondria:
•Required energy for the Flagellum
Acrosome (modified lysosome)
•Used to penetrate the egg
Testes/Spermatogenesis
Describe the temperature control process and the major components
Why they are outside of the body*
Spermatogensis occurs optimally at ~35 C
•Temperature regulation is mediated through (2) muscles & vasculature
Dartos muscle
- SM beneath the skin of the scrotum; Changes surface area Contraction → Wrinkling of the Scrotum
- Relaxation → Smooths out the Scrotum
Cremaster muscle
- SkM in the spermatic cord; Raises or lowers testis
- Contraction → Raises Testis
- Relaxation → Lowers Testis
Pampiniform plexus
- Venous network in the spermatic cord
- Counter current exchange system
- Venous blood carries away heat from adjacent arterial blood as it ascends
Sertoli cells
Describe the function and components
Sertoli Cells:
- Base: Sits on BL
- Apex: Extends to lumen
Function:
- Nutrient support
- Exocrine function
- Fluid (lowers friction & provides pathway for spermatids to “swim out”
- Endocrine function
- Androgen-binding protein (ABP)
- Inhibin
- Blood-testis barrier
Interstitium: Leydig Cells
Describe location & function
Leydig cells:
- Located between the tubules
- Make testosterone; Induces
- Epiphyseal cartilage closure
- Facial hair development
- Increased muscle mass
- Increased libido
- Spermatogenesis
- Erectile function*
Gonadal Hormone Regulation
Positive/Stimulating Reg
Negative/Inhibitory Reg
Consequences of Anabolic Steroids?
Positive Regulation
LH → Leydig cells → ↑ testosterone
FSH → Sertoli cells → ABP
Sertoli cells → ↑ activin → ↑ FSH → ↑ ABP
Negative Regulation
Testosterone → hypothalamus → ant pit → ↓ LH → ↓ Testosterone
Sertoli cells → ↑ inhibin → AP → ↓ FSH → ↓ ABP
Consequences of Anabolic Steroids (Androgen doping):
High levels of anabolic steroids induces feedback mechanisms to reduce Fertility
What is the Duct system?
Mnemonic?
- Seminiferous Tubules
-
Epididymis*
- Convoluted tubule
-
Vas Deferens
- Ampula
- Ejaculatory Duct
- Nothing
- Urethra
- Penis
“SEVEn UP”
Epididymis:
Describe the structure & function
Epididymis:
•Convoluted duct located behind the testis that serves as the Final maturation & storage site for spermatozoa
Consists of:
- Head
- Body
- Tail
Lined by Pseudostratified columnar epithelium
- Basal nuclei
- Apical Stereocilia
- Function: Increased surface area to Resorb fluid, concentrates sperm
Smooth muscle:
- Amount increases distally
- Slow, rhythmic contraction moves sperm down into the tail
- Intense contractions during ejaculation
Smooth m. & exocrine function of SnT constantly pushing sperm into Epididymis*
Environment limits sperm motility until ejaculation
Vas Deferens
Describe Structure & Function
Vas Deferens:
- Thick muscular tube
- (3) layers of Smooth Muscle
- Function: Propel sperm during ejaculation
- Lined with Pseudostratified columnar epithelium
Accessory glands
What glands are included?
Function?
Includes:
- Seminal Vesicle
- Prostate
- Periurethral Glands
Function:
- Nutrition
- Propulsion Fluid
Describe the contribution percentages of final sperm volume
- 70% Seminal Vesicle (SV)
- 25% Prostate
- <1% Bulbourethral & Urethral glands
- <5% Testes
Seminal Vesicle
Structure & composition
Products
Structure:
- Fibromuscular wall
- Mucosa thrown into numerous folds; Pseudostratified Columnar Epithelium
- (increase surface area)
Major secretions:
- Fructose: Sperm energy source
- Prostaglandins: motility enhancers
- Fibrinogen/semenogelin:
- Coagulate into a matrix to briefly hold the sperm in place following ejaculation
Androgen-dependent:
•Requires Testosterone (if reduced, it will regress)
Prostate:
Structure, products & function
Structure:
- Walnut-sized gland below the bladder
- Fibromuscular stroma
- Leaf-like papillary infoldings of mucosa (Pseudostratified columnar epithelium)
- Foldings increase w/ age
- Copora Amylacea: Hyaline Masses in the prostate lumen
- Increase w/ age & unknown significance
Secretions: Empties into prostatic urethra
- Polyamines, prostaglandins
- Prostate-specific antigen (PSA)
- Semen liquefaction – sperm release
Androgen-dependent*
Corpora Amylacea: What are they?
Hyaline cartilage masses in the prostate lumen
Increase with age
Significance unknown
Describe the structure of the Penis
Erectile tissue:
•Each Surrounded by Tunica Albuginea (Darker pink layer)
Corpora Cavernosa (2x)
•Blood vessels, CT, & Smooth m.
Corpus spongiosum (aka Corpus cavernosum urethra)
Glans
- Distal expansion of the Corpus Spongiosum
- Covered by the prepuce (foreskin)
Tissue type?
Function?
Erectile Tissue: Highly vascularized
Describe the differences between the Flaccid & Erectile state (Erectile Hydraulics)
Flaccid State: Limited Blood supply to erectile tissue
- Smooth m. surrounding helicine arteries is tonically contracted, thereby limiting blood flow
- Blood is routed to AV shunts
Erectile state: Psychogenic & reflex factors
- Nerves & vascular ECs produce nitric oxide (NO)
- NO activates guanylate cyclase (GTP-> increasing cGMP), thereby relaxing vascular Smooth m. surrounding Helicine a.
- Vascular spaces in erectile tissue fill with blood
- Engorged tissue compresses veins against the tunica albuginea, thereby blocking venous outflow
Explain the clinical basis of a hydrocele & where they can occur
Hydroceles can occur through:
- Infection-derived
- Failure to close Tunica Vaginalis
Usually resolves on it’s own.
Common in newborns – failure to close processus vaginalis (communicating) or impaired absorption (noncommunicating)– usually resolve spontaneously
Adults – age or scrotal injury
What is a Vasectomy?
Why is Libido unaffected?
Why is Ejaculate volume unaffected?
Where do the sperm go?
Vasectomy:
Removal or sealing of the vas deferens
Seals the vas deferens, Testosterone production continues
Ejaculate vol. is unaffected because Testis only contributes <5% of seminal fluid
Sperm die & get absorbed
