Download Male Reproductive System

MALE REPRODUCTIVE SYSTEM

Function
o Spermatogenesis
o Production of male sex hormones (androgens – testosterone)
o Semen production

Excretory Ducts – exocrine function (sperm + glandular products)
o Intratesticular Ducts:

Tubuli Recti (straight tubules)

1st component of excretory duct system

Intratesticular ducts at ends of seminiferous tubules near the rete testis

Epithelium transitions as follows:
o Seminiferous epithelium 
o Briefly sertoli cells only 
o Simple cuboidal (the rest)
o ???? I thought sertoli cells only = seminiferous epithelium ???

Rete Testis

Intratesticular duct system (epithelial-lined channels) w/in the mediastinum testis

Epithelium
o Simple cuboidal
o Apical surface

Single cilium

Short microvilli
o Extratesticular Ducts:

Ductuli Efferents (efferent ductules)

Rete testis channels converge  highly convoluted efferent ductules (10 -20)

Epithelium; pseudostratified columnar:
o Alternating

Tall columnar ciliated cells

Cuboidal non-ciliated cells possessing microvilli
o Incomplete layer of basal cells also present

Thin circular of smooth muscle surrounds ductules

Surrounding CT – highly vascularized

Fxn: reabsorption of most of fluid secretion from seminiferous tubules

Epididymal Duct (ductus epididymis)

Efferent ductules converge  head of epididymal duct

Single highly coiled tube (5 – 6 meters long)

Regions:
o Head
o Body
o Tail

Functions:
o Sperm maturation
o Sperm storage
o Sperm transport

Epithelium
o Pseudostratified columnar w/

Principal cells – fxn:

Continued absorption of testicular fluid (head)

Phagosytosis of abnormal spermatozoa & residual bodies (head)

Secretion of (body):
o Glycerylphophorylcholine (GPC)
o Glycoproteins
o Other molecules used for maturation of spermatozoa

Basal cells – may be precursors to the principal cells
o Apical – long, non-motile, branched stereocilia
(Note: stereocilia are elongated microvilli NOT true cilia)

Smooth muscle surrounds duct & gets progressively thicker
o Tail (3 layers) – fxn:

Storage of spermatozoa

Propulsion during ejaculation
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Ductus Deferens (vas deferens)

Continues directly from tail of epididymus

Component of spermatic cord

Tissues:
o Mucosa

Epithelium – Pseudostratified Columnar

Cells similar to epididymal duct, but shorter

Contains stereocilia to the level of ampulla

LP – elastic fibers
o Muscularis Externa (~1mm thick) – peristalsis during ejaculation

Inner longitudinal

Middle circular

Outer longitudinal
o Adventitia – LCT (blends with CT of spermatic cord)

Ampulla
o Dilated region of the ductus deferens adjacent to the prostate & seminal vesicle
o Epithelium becomes complexly folded & resembles seminal vesicle

Accessory Glands
o Seminal Vesicles

Pair of highly folded tubular glands

Largest contribution (50 – 70%) of volume of semen

Mucosa

General: extensive mucosal branching & folding  large surface area for secretion

Epithelium varies (w/ age or amt. of testosterone present):
o Mostly pseudostratifeid columnar
o May be simple columnar or cuboidal
o Secretes:

Fructose (principal metabolic substrate for sperm)

Other sugars

Bicarbonate (buffer)

Prostaglandins

Proteins

Amino acids

LP – vascularized LCT w/ many elastic fibers

Muscularis Externa

Inner circular

Outer longitudinal

Adventitia – collagenous CT containing elastic fibers
o Prostate Gland

Largest accessory gland

Surrounds the “prostatic segment” of urethra (lined w/ transitional epithelium)

Glands

Compound alveolar glands

Arranged in groups
o Main
o Mucosal
o Submucosal

Ducts coverge  excretory ducts that open into the prostatic urethera

CT Capsule extends into gland & divide it into lobes

Fibromuscular Stroma

Smooth mm cells

Fibroblasts

Elastic & collagenous fibers

Inadequate amts of testosterone result in

Δ in epithelial shape
o Pseudostratifeid columnar (most common)
o Simple columnar or cuboidal

Loss of or reduction in secretions:
o Prostate-specific acid phosphatase
o Citric acid
o Fibrinolysin (liquefies semen)
o Prostate specific Ag (a protease)
o Amylase

Lumina

May contain calcified bodies = prostatic concretions (diagnostic)
o H&E  red/pink
o Trichrome  blue/green

Clinical Correlations:

Benign Prostatic Hyperplasia
o Some men are affected by age 50, but most are affected by age 85
o Enlarged mucosal & submucosal prostatic glands

Gradually reduces lumen of urethra  difficult urination
o Involves stomal cell converstion:
testosterone  dihydrotestosterone (DHT) by 5-α reductase
o DHT

Autocrine factor on stroma cells

Paracrine factor on epithelium to produce growth (stroma & epithelium)

o
Prostatic Cancer
o Adenocarcinoma of the prostate

Common form of cancer in men

Affects ~ 30% of males > 75 yrs

Tumors normally develop in the main (outer) glands

May not impinge on urethera & t/f may not be detected by patient

Metastasize to bone frequent

Carcinomas cause ↑ in blood levels of the following (used to detect &
monitor disease progress):

Prostate Specific Acid (PSA)

PSA Phosphatase
Bulbourethral Glands (Cowpers Gland)

ALL-mucous secretory

Lined by a tall epithelium

Ducts

Located in urogenital diaphragm

Open into the penile urethra

Penis
o
o
o
o
o
Erectile tissue arranged:

Two dorsal cylinders (corpora cavernosa, CC)

Smaller ventral cylinder (corpus spongiosum, CS)

Contains the urethra

Expands distally to form the glans penis

Cylinders surrounded by dense collagenous sheath, the tunica albuginea
Penile skin

Contains abundant subcutaneous layer of smooth muscle

No adipose tissue
Urethra

Segments

Prostatic

Membranous

Penile – contained in corpus spongiosum
o Stratified or pseudostratified columnar
o Glands of Litré (mucous secreting) are common as urethral outpouchings
Erectile tissues (penis & clitoris)

Interconnecting vascular spaces composed of

Trabeculae
o DCT
o Smooth muscle

Lacunae
o Irregular vascular spaces lined with endothelium
o Flaccid (relaxed) state

Contains little blood

Main blood flow is dorsal artery  AV anastomoses  deep veins
o During erection

Smooth muscle in helicine aa & trabeculae relaxes

Arteries dilate & blood fills lacunae

Lacunae pressure causes the tissue to expand against tunica albuginea

Tunica albuginea consists of iDCT t/f inexpandable & thus: erection
Clinical Correlation – Erectile disfunction

Acetylcholine

Transmitter released by PS nerves in penis/clitoris

Acts on erectile tissue endothelium  Nitric Oxide

Nitric Oxide (NO)

Spreads into smooth muscle of the trabeculae & helicine arteries

Causes an enzyme, guanylate cyclase produce  cGMP

cGMP

relaxes the smooth muscle

↑ blood flow in the helicine arteries produces erection by filling of the lacunae

Specific phosphodiesterase production

Counteracts erection by breaking down cGMP  constriction of smooth muscle

Sildenafil citrate

Specific phosphodiesterase inhibitor

Suppresses the destruction of cGMP, allowing erection to occur