Male Reproductive System - Histology
Prostate Cancer
- Affecting 1 in 20 males - PSA test dramatically increased early diagnosis and management of this disease - Current controversy with use of PSA blood test alone as screening mechanism-elevated level of PSA linked to BPH and prostatitis leading to false positive screening on PSA alone
Genital Duct System - Erectile Tissue
- Collection of vascular spaces lined by vascular epithelium, fibroelastic trabeculae are interwoven with smooth muscle between these vascular spaces - Erectile tissue masses are surrounded by a dense, fibroelastic layer called the tunica albuginea which binds these components of the penis together - Composed of 3 cylinders of erectile tissue •Dorsally the corpora cavernosum (2 paired) •Ventrally the corpus spongiosum (single) -The penile urethra is found in the spongiosum
Vasectomy
- Contraceptive procedure that severs the vas deferens - Sperm-specific antibodies are produced as sperm from the cut end of the vas may enter the surrounding tissues.
Benign Prostatic Hypertrophy
- Hyperplasia of glandular and connective tissue of the prostate gland - Urethra constricted by enlarged prostate - urination difficulty
Kartagener's syndrome
- Immotile cilia syndrome - Infertility in men because their spermatozoa are immotile - Chronic respiratory infections-cilia not able to clear debris from the respiratory tract.
Cryptorchidism
-Failure of the testes to descend into the scrotum -Impact on sterility and risk of testicular malignancy
Erectile Dysfunction
-Inability to achieve and maintain sufficient penile erection to complete ejaculation -Linked to disorders of blood flow to penis -Linked to parasympathetic nerve damage
Clinical Features
1) Cryptorchidism 2) Kartagener's Syndrome 3) Benign prostatic hypertrophy 4) Prostate Cancer 5) Erectile dysfunction 6) Vasectomy
Structures in the Conducting System
1) Epididymis 2) Prostate Gland 3) Vas deferens 4) Ejaculatory duct 5) Male urethra
What is the function of the male reproductive system?
1) Production of semen and gametes: spermatozoa and seminal fluid 2) Production of male sex hormones 3) Facilitation of fertilization: delivery of gametes into the female reproductive tract
Accessory Male Sex Glands
1) Prostate - single gland (unpaired); it contains the urethra and receives the ejaculatory ducts. 2) Seminal Vesicles = paired glands located near the bladder and the prostate gland. 3) Bulbourethral glands = paired, compound tubulo-alveoular glands
Summary/ Review
1) Structure and epithelium 2) Secretions 3) Hormonal Influences
Genital Duct System
1. Intratesticular Ducts a. Tubuli Recti b. Rete Testis 2. Extratesticular Ducts a. Efferent ducts b. Epididymis c. Vas or ductus deferens 3. Accessory Sex Glands a. Seminal vesicles b. Prostate gland c. Bulbourethral glands 4. Erectile Tissue and the Penis
What is the role of ABP?
ABP is under the influence of FSH. Testosterone binds to ABP-this complex exists in the lumen of the seminiferous tubules to maintain high concentrations of testosterone which enhances spermatogenesis.
Genital Duct System - Prostate Gland
Accessory Reproductive Glands Has a central lumen which is the prostatic urethra Complex tubuloalveolar gland, with multiple ducts that open into the prostatic urethra Glandular epithelium is varied from simple columnar to pseudostratified-likely to vary with testosterone levels May contain concretions = corpora amylacea Smooth muscle present in wall of gland Prostate has a dense capsule
Genital Duct System - seminal vesicles
Accessory Reproductive Glands Highly folded paired glands located near the bladder Mucosa is thrown into folds giving the appearance of multiple chambers, however there is only one lumen. Lined by pseudostratified columnar epithelium Wall consists of fibroelastic CT with smooth muscle Secretory product = 70% of the ejaculate
What are the Glands of Littre?
Adjacent to the lumen of the urethra. Secrete mucus
Spermatids
Advanced in maturity, found closer to the lumen of the tubule. Many attached to the apical portion of the Sertoli cell. Developing tail in these cells
What is the function of stereocilia?
Aid in absorption Sperm are initially nonmotile as they leave the seminiferous tubules, large volumes of fluid are secreted to propulse spermatozoa. Core function of stereocilia is to resorb this large volume of fluid (90% of fluid volume), as the spermatozoa start to become motile in the epididymis.
Secretion
Andorgen binding protein - Sertoli Cells Testosterone - Leydig Cells Inhibin - Sertoli Cells
Spermatogenic Cells
Arranged in ill-defined layers of advancing development between the Sertoli cells The most immature cells, called spermatogonia rest on the basal lamina The most mature cells, spermatids, attached to the apical portion of the Sertoli cells extending into the lumen of the tubule.
Where are the efferent ducts located and what do they lead to?
Begin in testis Leads to epididymis
Interstitial Tissue
Blood and lymph vessels Cells of Leydig (release testosterone)
Testis - structure and organization
Capsule = CT called the tunica albuginea - CT of capsule extends into the organ as septa, delineating lobules. - CT of capsule thickens at the mediastinum in the region of the rete testis (posterior surface of the testis).
Sertoli Cells - Structural Features
Columnar shape Extends the entire thickness of the epithelium Pale and oval nucleus with prominent nucelolus Surrounds adjacent spermatogenic cells forming compartments within the thickness of the tubule
Male Urethra
Composed of 3 named parts = prostatic, membranous, and penile portions
What are the characteristics of semen?
Contains fluids and sperm from the testis and secretions from the epididymis, ductus deferens, prostate, seminal vesicles, and bulbourethral glands. It is alkaline which may assist in neutralizing the acid environment of the vagina.
What does the secretory product of the seminal vesicles contain?
Contains fructose and also produces prostaglandins Smooth muscle in seminal vesicles will contract during ejaculation and move this fluid into the ejaculatory ducts and through the urethra.
Prostate Gland
Donut shaped structure below the urinary bladder - the opening in the middle is the urethra (prostatic portion of the urethra) Prostatic urethra located in the prostate and leads to the penile urethra
What is the function of the bulbourethral gland?
During sexual arousal each gland produces a clear, salty, viscous secretion known as pre-ejaculate. Pre-ejaculate lubricates the urethra for spermatozoa to pass through, neutralizing traces of acidic urine in the urethra. Also, helps to flush out any residual urine or foreign matter. Possible for this fluid to pick up sperm as well.
Lobules
Each lobule consists of one to four seminiferous tubules. Connective tissue stroma surround these highly convoluted and looped tubules. Tubules end near the mediastinum in short straight tubules (tubuli recti). These tubuli recti are continuous with the rete testis, which is an anastomosing system of channels in the mediastinum.
What is the importance of testosterone in the embryo?
Essential for the development of gonads in the male fetus
Genital Duct System - Efferent Ducts
Extratesticular Ducts Collection of 10-20 tubules leading from the rete testis to the epididymis. Lined by pseudostratified columnar epithelium with cilia Surrounded by smooth muscle Tall and short cells produce a fluted, wavy appearance to to the lumen
Genital Duct System - Vas Deferens
Extratesticular Ducts Continuation of the epididymis Unlike the epididymis, the lumen of the duct does not appear uniform and smooth Enters the abdominopelvic cavity as a component of the spermatic cord -Terminates to form the ejaculatory duct -Thick muscular coat •Lined by pseudostratified columnar epithelium
Genital Duct System - Epididymis
Extratesticular Ducts Newly produced sperm mature and acquire motility here. Lined by a pseudostratified columnar epithelium. - Tall cells called principal cells, have stereocilia - Short cells in a basal position Smooth muscle surrounds each duct profile Epididymis serves as a reservoir for mature sperm.
Hormonal Influences
FSH acts on Sertoli cells to increase inhibin which decreases FSH release LH acts on Leydig cells to increase testosterone Prolactin acts on Leydig cells to increase testosterone
What happens if the testes fail to descend?
Failure of the testis to descend into the scrotal sac is called cryptorchidism and has implications on spermatogenesis and increases the risk of testicular malignancy.
What are the features of the spermatid phase?
Formation of the acrosomal structure (which houses hydrolytic enzymes) Acrosome expands over the nucleus Nucleus condenses to the head region Formation of flagellar structure Mitochondria aggregate around flagella Cytoplasm diminished and the tail elongates Non-motile spermatozoa are released into the lumen of the seminiferous tubules.
Cells of Leydig - Structural Features
Found in clusters between the tubules Large, polygonal in shape and they typically contain lipid droplets
Seminiferous Tubules
Highly convoluted and looped Lined by seminiferous epithelium: - 4-8 cell layers thick - Only two cell types - Sertoli cells - Spermatogenic cells Each tubule is surrounded by peritubular tissue and interstitial tissue is located in between the profiles and loops of the tubules.
Where are the seminiferous tubules located and what do they lead to?
In testis Leads to tubuli recti
What are the two categories of the conducting system?
Intratesticular = seminiferous tubules, tubuli recti, rete testes, and efferent ducts Extratesticular = epididymis, vas deferens, ejaculatory duct, and prostatic urethra
Genital Duct System - Rete Testis
Intratesticular Ducts Labyrinths of interconnecting channels in the mediastinum of the testis. They are lined by a simple cuboidal epithelium, a feature to note is the presence of apical cilium
Genital Duct System - Tubuli Recti
Intratesticular Ducts Tubuli recti are the terminal portion of the seminiferous tubules. They are best described as a series of short, straight tubules. Textbooks note that these are transition structures with a lining of Sertoli cells only. Transition to cuboidal epithelium
Spermatogenesis
It is divided into three phases 1) Spermatogonial phase 2) Spermatocyte phase 3) Spermatid phase
What is the importance of fructose?
It is the principal metabolic substrate for sperm
Peritubular Tissue
Lamina propria with fibroblasts, myoid cells (exhibit contractile properties), and collagen fibers
What epithelial cells line the urethra?
Lined by a pseudostratified columnar epithelum, which is surrounded by a loose CT sheath.
Prostatic Urethra
Lined by transitional epithelium
Ejaculatory Duct
Located in prostate gland and leads to prostatic urethra Paired opening into the prostate gland - specifically the prostatic urethra.
Where are the tubuli recti located and what do they lead to?
Located in testis- ends of seminiferous tubules. Leads to the rete testes. Tubuli recti connect the seminiferous tubules to the rete-testes channels.
Where are the rete testes located and what do they lead to ?
Located in testis-mediastinum Lead to efferent ducts
Epididymis
Located: Near testis Lead to: Vas deferens Ductus epididymis is a crescent shaped structure adjacent to the testis within the scrotum
What are the characteristics of stereocilia?
Long cytoplasmic projections, but have no motility. Extensions increase the surface area of the cell allowing for greater absorption and secretion.
What is located on the posterior surface of the testis?
Mediastinum Blood Vessels Lymphatic Vessels Rete Testis
What is the importance of smooth muscle throughout the genital duct system?
Move products farther down track.
Spermatid phase
No cell division-only remodeling to form mature sperm. Also called spermiogenesis
Which cells are found in the adluminal compartment?
Primary spermatocyte Secondary spermatocyte Spermatids Mature sperm
Spermatocyte phase
Primary spermatocytes undergo 2 meiotic divisions to produce spermatids: Spermatids are haploid in DNA content and chromosome number.
Spermatogenesis
Process that produces sperm Five categories of cells: 1) Spermatogonia - in the basal compartment 2) Primary spermatocyte 3) Secondary spermatocyte 4) Spermatids 5) Mature sperm
What are the secretions of the prostate gland?
Prostatic acid phosphatase (PAP) - also used as a marker of prostate cancer Fibrinolysin - liquefies semen Citric Acid Prostate-specific antigen (PSA) - enzyme is serine protease - Marker for prostate cancer
What are corpora amylacea?
Prostatic concretions, small hyaline masses Varied shapes and sizes. They are more frequent with advancing age.
Cells of Leydig - Functional Features
Secrete testosterone throughout life 1) In the embryo 2) At puberty
What is the importance of testosterone in the adult?
Secretion of testosterone is needed for the maintenance of spermatogenesis and accessory glands and ducts
Structure and Epithelium
Seminiferous tubule --> Seminiferous epithelium Tubuli Recti --> Sertoli cells Rete Testes --> Cuboidal Efferent Ductules --> Pseudostratified Epididymis --> Pseudostratified Vas deferens --> Pseudostratified Prostate gland --> Pseudostratified/ columnar Prostatic urethra --> Transitional Seminal vesicle --> Pseudostratified Penile urethra --> Pseudostratified/ stratified squamous
Which cells are found in the basal compartment?
Spermatogonia
Spermatogonial phase
Spermatogonia form primary spermatocytes
Sertoli Cells - Functional Features
Support and nurture developing sperm cells Protect developing sperm cells from immune system Secrete fluid into the lumen that facilitate transport of spermatozoa Possess receptors for FSH Produce Anti-Mullerian hormone in the embryo --> prevents development of Mullerian ducts which form portions of the female reproductive system Synthesize Androgen-binding protein (ABP) Phagocytose excess cytoplasma discarded by maturing spermatids. Secrete inhibin
What is the importance of testosterone during puberty?
Testosterone is key for the initiation of sperm production, sex gland secretion, and development of secondary sexual characteristics
What are the accessory glands?
The accessory glands consist of the prostate, seminal vesicles and the bulbourethral glands.
What is the definitive male reproductive system?
The male reproductive system is comprised of: 1) Testis 2) System of genital ducts (both intratesticular and extratesticular or excurrent) 3) Accessory sex glands 4) Penis
Organization of the System
The testes are paired structures located in the scrotum. The testes have important anatomic relationships to coverings and components of the scrotum that you will study in the gross lab.
Seminiferous Tubules
The testis contain the seminiferous tubules. These seminiferous tubules are the locations for production of sperm and are therefore connected to the conducting system of ducts or named tubules.
Visceral layer of the tunica vaginalis
The tunica vaginalis is a double layer of squamous epithelium, shaped into a flattened balloon, located adjacent to the testis. In histology lab we will see it as a mesothelial lining forming the outermost layer of the testis, similar to our description of "serosa‟ in the GI tract lab.
What is the purpose of the accessory glands?
They produce components of semen, the prostatic, and seminal fluids.
Vas Deferens
Travels in spermatic cord and leads to the ejaculatory duct Ductus deferens = spermatic duct - the tube conveying sperm from the testis into the abdominal-pelvic cavity. It is a component of the spermatic cord, palpable within the scrotum. The terminal portion of the vas connects with the duct of the seminal duct to form the ejaculatory duct.
What is the blood-testes barrier?
• Isolates the system from developing germ cells-preventing autoimmune response • Isolates germ cells from local drugs, antibodies, etc • Formed by Sertoli cell junctional complexes --> forming two compartments within the tubule wall- the basal and the adluminal (ad = towards) • Maintains the optimal environment for germ cell differentiation.
