Module 6.2 Male Reproductive System and Special Sense Flashcards
Consists of:
- Two gonads, the testes, which produce male germ cells and male sex hormones
- A copulatory organ, the penis
- A set of tubes and tubules which transmit the male germ cells from the testes to the penis
- Accessory glands – seminal vesicle, prostate gland and bulbourethral glands, which provide a fluid medium for carrying the male germ cells
Male Reproductive System
Gonads – primary sex organs
Testes in males
Ovaries in females
Gonads produce gametes (sex cells) and secrete hormones
Sperm – male gametes
Ova (eggs) – female gametes
(Development of the Gonads)
These appear as a pair of longitudinal ridges which are formed by proliferation of the coelomic epithelium and condensation of the underlying mesenchyme called the __ during the 5th week of development.
genital ridge or gonadal ridge
(Development of the Gonads)
In the 6th week of development, the primordial germ cells derived from the yolk sac __, invade the genital ridge.
endoderm
(Development of the Gonads)
During the arrival of the primordial germ cells, the coelomic epithelium of the genital ridge proliferates and epithelial cells penetrate the underlying mesenchyme forming irregularly shaped cords, the __.
primitive sex cords
(Development of the Gonads)
Before the 7th week of development, the gonads of the two sexes are identical in appearance and are called __.
indifferent gonads
(Sex Determination)
__ is determined by the testis determining factor / TDF on the Y chromosome.
Gonadal sex
(Development of the Testis)
If the embryo is genetically male, the primitive sex cords continue to proliferate to form the testes or medullary cords. Later, this gives rise to the __.
seminiferous tubules and the rete testis
(Development of the Testis)
Then the testis cords will lose its contact with surface epithelium and will be covered with a dense layer of connective tissue, the __.
tunica albuginea
(Development of the Testis)
The testis cords are composed of __
primitive germ cells and Sertoli cells
(Development of the Testis)
The __ are derived from the mesenchyme of the gonadal ridge located between the testis cords.
Leydig cell
(Development of the Testis)
From the 8th weeks of development, the Leydig cells secrete testosterone, which induces masculine differentiation of the mesonephric ducts and external genitalia. While the Sertoli cells secrete __ which inhibits development of the paramesonephric ducts.
Mullerian inhibiting substance
(Development of the Testis)
Due to the rapid growth of the dorsal wall of the embryo, the testes gradually descend behind the abdominal position until the __.
7th month
(Development of the Testis)
From the 7th month until birth, there is progressive shortening of gubarnaculum testis. At birth, the testis is inside the __.
scrotal sac
Coverings of the testes
Tunica albuginea – capsule that surrounds each testis
Septa – extensions of the capsule that extend into the testis and divide it into lobules
- Tightly coiled structures
- Function as sperm-forming factories
- Empty sperm into the rete testis
seminiferous tubules
- Each lobule contains one to four seminiferous tubules
- Sperm travels through the rete testis to the epididymis
- Interstitial cells produce androgens such as testosterone
- are compound tubular glands lodged in the scrotum.
Testes
The __ is a pendulous bag of skin with a thin wall, an incomplete layer of smooth muscle (Dartos muscle) and some subcutaneous tissue. It has a considerable surface area and it is believed that this permits its contents to be maintained at a temperature slightly below that of the body. This lower temperature is important for spermatogenesis or the production of sperm cells.
scrotum
- develop retroperitoneally within the abdominal cavity.
- They descend into the scrotum, where the cooler temperature are more hospitable for spermatogenesis
Testes
Testes
- During the descent of the testis, it carries an evagination of the peritoneal cavity into the scrotum.
- Usually, the connection between this processus vaginalis and the peritoneal cavity proper in obliterated later in life, leaving a tunica vaginalis.
- The anterior and lateral aspects of the testes are coated with a mesothelium that once was continuous with the mesothelium lining the peritoneal cavity.
The testes is surrounded by three layers of testicular capsule:
- an outer tunica vaginalis
- middle tunica albuginea
- inner tunica vasculosa.
The __ contains a network of blood vessels.
tunica vasculosa
- is a thick, fibrous connective tissue capsule that lies beneath the mesothelium.
- It penetrates deeply into the posterior aspect of the testes, forming the mediastinum testis
tunica albuginea
- is located in the mediastinum testis.
- It is through here that ducts, blood vessels, nerves, and lymphatic vessels enter and leave.
hilus of the testis
Along the posterior border of each testis, the capsule becomes greatly thickened and is known as the __.
mediastinum testis
The __ divide the testis into numerous pyramidal compartments called testicular lobules.
fibrous partitions (septuli testis)
(Testes)
Each lobule contains one to four highly convoluted seminiferous tubules supported by fibrous connective tissue containing the __, which are large cells with an endocrine function
interstitial cells of Leydig
(Testes)
At the apex of the lobule, each lobule becomes a straight lobule called the __.
tubuli recti
(Testes)
The tubuli recti in turn anastomose and form a network of tubules called the __ which is found in the mediastinum testis.
rete testis
(Testes)
Arising from the rete testis are about 2 – 15 convoluted tubules called the __, which passes to the head of the epididymis.
ductuli efferentes
(Testes)
The highly tortuous __ forms the body and tail of the epididymis.
ductus epididymis
From the tail of the epididymis emerges the ductus deferens (vas deferens), one of the components of the spermatic cord. It ascends into the abdominal cavity to terminate behind the urinary bladder. Its’ terminal end forms a fusiform dilation called ampulla of the vas deferens. The terminal end of the ampulla fuses with the excretory duct of the seminal vesicle to form the __.
ejaculatory duct
The ejaculatory duct pierces the prostate gland to open into the prostatic urethra to the side of the __.
prostatic utricle
The wall of the __ is made up of a seminiferous epithelium, thin basement membrane and an outer capsule of fibro-elastic connective tissue.
seminiferous tubule
(SEMINIFEROUS TUBULES)
The lining epithelium is a complex stratified epithelium composed of two distinct categories:
- Supporting cells
- Spermatogenic cells
- The interstices between seminiferous tubules are filled with small vessels and lymphatics.
- Connective tissue fibroblasts and, possibly, macrophages and lymphocytes occur here.
- Most importantly, the Leydig cells, specialized for the secretion of the male sex hormone, testorterone, are found here.
Interstitial Cells
- Also known as sustentacular or Sertoli cells.
- These cells have a supportive function in relation to the spermatogenic cells. They are tall, slender, elongated with irregular outline, rest on the basement membrane and extend through the full thickness of the epithelium. The cytoplasm contains numerous organelles with a well developed SER at the base of the cell, probably significant in the secretory function of the cell.
SUPPORTING CELLS
- Electron microscopy reveals pairs of apposed membranes (tight junctions) between adjacent Sertoli cells and between germ cells. This plays an important role in the formation of a blood-testis permeability barrier which isolates and protects the differentiating spermatogenic cells. It represents a barrier between the lumen of the semineferous tubule and the extratubular compartment.
- The spermatogonia that rest on the basement membrane have a good supply of nutrients, but the cells nearer the lumen of the tubule have no direct access to tisssue fluid because of the intervening Sertoli cells.
SUPPORTING CELLS
Dividing spermatocytes, spermatids and spermatozoa are nourished by the __.
Sertoli cells
Functions of the Sertoli Cells
- Provide mechanical support and protection to the developing germ cells.
- Provide nutrition for the developing germ cells.
- Play an active role in the release of spermatozoa.
- Phagocytosis of cellular fragments.
- Formation of blood-testis permeability barrier.
The __, from the bulk of the epithelium, give rise to mature spermatozoa by spermatogenesis. Spermatogenesis refers to the entire sequence of events wherein spermatogonia are transformed into spermatozoa.
spermatogenic cells
- Production of sperm cells
- Begins at puberty and continues throughout life
- Occurs in the seminiferous tubules
Spermatogenesis
Processes of Spermatogenesis
- Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty
- Follicle stimulating hormone (FSH) modifies spermatogonia division
- One cell produced is a stem cell
- The other cell produced becomes a primary spermatocyte
- Primary spermatocytes undergo meiosis
- Haploid spermatids are produced
- Spermatogenesis takes 64 to 72 days
Divisions of Spermatogenesis
- Spermatocytogenesis - Mitosis of spermatogonia to become spermatocytes
- Meiosis - Maturation division of spermatocytes which reduce the chromosome number by half and produces spermatids
- Spermiogenesis - Spermatids are transformed directly into spermatozoa
- Located beneath the basement membrane of the seminiferous tubules.
- Contain a round, dark staining nucleus.
Spermatogonia
Spermatogonia: 2 Types
- Type A spermatogonia
2. Type B spermatogonia
- Contain an oval nucleus with fine chromatin granules.
- Its cytoplasm is homogenous and pale staining.
- The nucleolus lies close to the nuclear membrane.
- These cells undergo a series of mitotic divisions that give rise to other Type A spermatogonia, while other differentiate into Type B spermatogonia.
Type A Spermatogonia
- Contain a spherical nucleus containing chromatin masses which are heavily stained, large and of varying sizes.
- The single nucleolus is centrally located and the cytoplasm is somewhat dark staining.
- These cells give rise to primary spermatocytes.
Type B Spermatogonia
- The biggest of the spermatogenic cells with plenty of mitotic figures in their nuclei.
- These are seen in various stages of prophase because the stage of mitotic prophase is extremely prolonged.
- These undergo the first meiotic division and become transformed into secondary spermatocytes.
Primary Spermatocytes
- These are spherical or polygonal in shape with a small, dark staining nucleus with finely granular chromatin.
- These cells undergo spermiogenesis and become transformed into mature germ cells.
- Only few are seen in section because they transform rapidly into spermatozoa.
Secondary Spermatocytes
- Spermatozoa begin to proliferate rapidly at puberty and, by division, produce primary spermatocytes
- Primary spermatocytes enter meiosis I, the first meiotic division, and produce secondary spermatocytes
- In meiosis II, secondary spermatocytes divide and form haploid spermatids
Spermatogenesis
- Mature sperm cells, actively motile, swim freely.
- Consists of a head, middle piece, body and a tail.
- They are quiescent in the seminiferous tubules and ducts of the testis and become active by the secretion of the accessory glands.
- Production begins at puberty, continues throughout life but diminishes with age.
Spermatozoa
- Refers to the process of converting spermatids into spermatozoa.
Spermiogenesis
There are three events during spermiogenesis
- Acrosome formation
- Flagellum and midpiece formation
- Streamlining of spermatozoa
- Golgi membranes coalesce to form an acrosomal granule
- The acrosomal granule flattens around the nucleus to form an acrosomal cap
Acrosome Formation
- Centrioles migrate to the spermatid pole, opposite the acrosome
- One centriole forms a flagellum
- Mitochondria group around the base of the flagellum to form the midpiece
Flagellum and Midpiece Formation
- Nuclear condensation results in a pointed streamlined nucleus
- Excess cytoplasm is shed as a residual body which is engulfed by the Sertoli cells
Streamlining of Spermatozoa
Structure of a Mature Sperm Cell
- The only human flagellated cell
- DNA is found in the head
- These are clusters of epitheloid cells which are largely cells with pale staining spherical to oval nuclei.
- They are usually acidophilic and found scattered in the stroma between the sminiferous tubules.
- These cells secrete testosterone.
Interstitial Cells of Leydig
- are about 20 micrometer in diameter and usually are found in close association with small blood vessels; this is not surprising since they are responsible for the secretion of testosterone into the blood
- has an acidophilic cytoplasm and a prominent nucleus with a nucleolus, when seen in the light microscope
- With the electron microscope they exhibit an abundance of smooth endoplasmic reticulum and a prominent Golgi apparatus
- contain cholesterol which they use to synthesize testosterone on membranes of the smooth endoplasmic reticula
Leydig cells
The production of androgen by Leydig cells is under the control of the __
pituitary gland
Cells of the pars distalis secrete __, which sometimes is called interstitial cell-stimulating hormone (ICSH). It is a gonadotrophic hormones, stimulates the Leydig cells to release testosterone
luteinizing hormone (LH)
High levels of testosterone then feed back on the hypothalamus and inhibit the production of __ in a classic negative feedback loop
luteinizing hormone relealsing hormone (LH-RH)
Following hypophysectomy, there is a complete degeneration of the __, no testosterone production, and a cessation of spermatogenesis
interstitial cells of Leydig
Following castration, testosterone levels fall rapidly and the gonadotrops are under chronic hypothalamic stimulation by LH-RH, resulting in the appearance of __ in the pars distalis
castration cells
- The most important hormone of the testes
- Produced in interstitial cells
Testosterone
Functions of testosterone
- Stimulates reproductive organ development
- Underlies sex drive
- Causes secondary sex characteristics
- Deepening of voice
- Increased hair growth
- Enlargement of skeletal muscles
- Thickening of bones
Testicular Drainage Ducts
- Tubuli recti
- Rete testis
- Efferent ductules
- Epididymis
- Ductus deferens
- Ejaculatory ducts
- Straight portions of loops of seminiferous tubules
- Lined by Sertoli cells
- Join the rete testis
Tubuli Recti
- Conveys gametes from the tubuli recti to the efferent ductules
- Lined by cuboidal ciliated cells
Rete Testis
- Continuous with the rete testis
- Empty into the epididymis
- Surrounded by smooth muscle cells
- The simple epithelium is lined by alternating groups of tall columnar ciliated cells and low columnar non-ciliated cells.
- Thus, the lumen is irregular and described as having a “festooned appearance”.
- The cilia help in transporting spermatozoa to the epididymis.
Efferent Ductules
- Lined by a tall pseudostratified epithelium
- The tall cells have long, apical nonmotile stereocilia.
- These are secretory cells also, producing certain constituents of ejaculate
- Short cells rest on a basement membrane and probably serve as a stem cell population to replace effete tall cells
Epididymis
- probably modifies the contents of ejaculate by removal and addition of various materials (i.e., stereocilia absorb and tall columnar cells secrete)
- Spermatozoa from the head of the epididymis are poorly motile and incapable of fertilizing ova in vitro
- Whereas spermatozoa from the tail of the epididymis are highly motile and capable of fertilizing ova in vitro. This change in the spermatozoa is called capacitation
Epididymis
- Comma-shaped, tightly coiled tube
- Found on the superior part of the testis and along the posterior lateral side
- Functions to mature and store sperm cells (at least 20 days)
- Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens
Epididymis
- Highly convoluted tubule which functions as storage organ of the spermatozoa.
- It is also where the sperm cells acquire the properties of motility and fertilizability.
- The lining epithelium is pseudostratified columnar with stereocilia.
- Scattered among the columnar cells at various levels in the epithelium are small cells with pale staining cytoplasm and dark heterochromic nuclei. These are termed “halo cells” which are intraepithelial lymphocyte
DUCTULI EPIDIDYMIS
Gross Anatomy of Ductus Deferens
- The tubular ductus deferens (vas deferens) recieves spermatozoa and secretions from the epididymis and conveys them to the prostate.
- Near the epididymis the ductus deferens is relatively coiled, but close to the prostate it is rather straight
Gross Anatomy of Ductus Deferens (2)
- Proximal to the prostate gland, the ductus deferens is dilated into an ampullary portion, where it is joined by a sac-like diverticulum called the seminal vesicle
- After they join, the ductus deferens and seminal vesicle enter the prostate as an ajaculatory duct
- is lined by a pseudostratified epithelium that is supported by testosterone secretion from Leydig cells
- The tall columnar cells of this epithelium bear long, nonmotile microvilli called stereocilia
- has a mucosa, a muscularis and an adventitia
ductus deferens
Histology of Ductus Deferens
- The mucosa is thrown into gentle undulations
- It has a thin lamina propria
- The muscularis is composed of three concentrically arranged layers – an inner and outer layer arranged longitudinally and a middle circular layer
- The adventitia contains small amounts of connective tissue, blood vessels and nerves
- It lacks a mesothelium
- In the ampullary portion of the ductus deferens, the mucosal folds are considerably higher and more complicated
- The ampulla, like the seminal vesicle, looks like a gland
- Carries sperm from the epididymis to the ejaculatory duct
- Passes through the inguinal canal and over the bladder
- Moves sperm by peristalsis
- Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue sheath
- Ends in the ejaculatory duct which unites with the urethra
Ductus Deferens (Vas Deferens)
– cutting of the ductus deferens at the level of the testes to prevent transportation of sperm
Vasectomy
- Also known as the vas deferens.
- The mucosa is lined by pseudostratified columnar epithelium. Together with the lamina propria, it is thrown into several longitudinal folds so that the lumen is narrow and irregular in outline.
- The muscularis layer is the thickest layer and gives the vas deferens a firm consistency. It is made up of inner longitudinal, middle circular and outer longitudinal layers. The muscles propel the seminal fluid during ejaculation.
DUCTULI DEFERENS
- The adventitia is loose fibroelastic connective tissue and blends with the tissues of the spermatic cord.
- The spermatic cord consists of the vas deferens and its accompanying artery, pampiniform plexus of veins and nerves. The cord is enclosed by the cremaster muscle.
- The ampulla of the vas deferens has a wider lumen and the mucosa is much more folde
DUCTULI DEFERENS
The primitive genital ducts consist of 2 parts namely:
- Mesonephric duct (Wolffian duct)
- Paramesonephric duct (Mullerian duct)
(Development of the Male Genital Ducts)
In males, the __ persists as the ductal system of the testis. The paramesonephric duct regresses.
mesonephric duct
(Development of the Male Genital Ducts)
From the cranial to the caudal position, the __ gives rise to the epididymis, ductus deferens and ejaculatory ducts. The ductus deferens gives rise to a saccular pouch which forms the seminal vesicle.
mesonephric duct
- Formed by the union of the ampulla of the vas deferens and excretory ducts of the seminal vesicle.
- Opens into the prostatic utricle.
- Lined by pseudostratified columnar epithelium.
- These ducts penetrate the prostate and join the prostatic urethra in a single midline thickening of the mucosa known as the colliculus seminalis
EJACULATORY DUCTS
ACCESSORY GLANDS
- Seminal vesicle
- Prostate gland
- Bulbo-urethral glands
- Penis
- A pair of convoluted sacs behind the urinary bladder which secretes and stores a yellow, viscous alkaline fluid rich in fructose that nourishes the spermatogenic cells and forms part of the seminal fluid.
SEMINAL VESICLE
- Located at the base of the bladder
- Produces a thick, yellowish secretion (60% of semen)
- Fructose (sugar)
- Vitamin C
- Prostaglandins
- Other substances that nourish and activate sperm
SEMINAL VESICLE
Like the ductus deferens, each seminal vesicle is lined by a __ that is supported by testosterone secretion from Leydig cells
pseudostratified epithelium
SEMINAL VESICLE
- With the electron microscope, the tall columnar secretory cells of the epithelium show a basal rough endoplasmic reticulum, a prominent Golgi apparatus and secretory granules
- The smooth muscle layers in the seminal vesicle are not neatly arranged; rather, they merge indistinctly into the smooth muscle surrounding the ejaculatory duct and into the prostate
Functions of the Seminal Vesicle
- Produce a substantial volume of the ejaculate
- Secretion of the seminal vesicles is viscous and yellowish
- Secretion contains materials that are probably nutrtitive for the spermatozoa
- Secretion contains prostaglandin
- The mucosa forms a complicated series of primary folds which branch into secondary and tertiary folds.
- The lining epithelium is pseudostratified columnar epithelium.
- The tunica muscularis is composed of smooth muscles in two layers: inner circular and outer longitudinal.
- The tunica adventitia is dense collagenous tissue with blood vessels, lymph vessels and nerves.
SEMINAL VESICLE
- Encircles the upper part of the urethra
- Secretes a milky fluid
- Helps to activate sperm
- Enters the urethra through several small ducts
Prostate Gland
- This is a compound tubulo-alveolar gland located below the urinary bladder and surrounds the first part of the urethra.
- It is surrounded by a fibroelastic capsule that also contains smooth muscle. The capsule gives off fibromuscular septa which divides the gland into lobes and lobules.
- The alveoli are lined by pseudostratified columnar epithelium.
- The cells secrete a thin, somewhat milky fluid. It is the main source of acid phosphatase, citric acid and amylase of semen.
PROSTATE GLAND
- is compact mass of smooth muscle and elaborately branched glands.
- A more detailed inspection reveals two types of glands:
- Periurethral mucosal glands
- Main secretory glands of the prostate proper
Prostate Gland
- Although small, these glands commonly undergo hyperplastic growth with advancing age.
- As a result, benign prostatic hyperplasia occurs, constricting the prostatic urethra
- BPH can be corrected surgically by a transurethral resection
periurethral mucosal glands
- The epithelium of this gland is columnar or pseudostratified at the gland’s main segment but grades into transitional epithelium where the gland empties into the prostatic urethra
- When viewed in the electron microscope the epithelial cells appear typical for protein-secreting cells
main secretory glands of the prostate proper
Functions of the Prostate Gland
- The prostate produces the majority of the volume of seminal fluid
- The secretions of the prostate are rich in proteolytic enzymes (especially fibrinolysin), which probably function to liquify the semen after it is deposited in the vagina
- Presumably, this liquefaction allows spermatozoa to free themselves from the viscous ejaculate and begin traveling through the cervix and uterus to the oviducts
- These secretions solidify sometimes in the gland and can be seen, especially in older men, as prostatic concretions
(Prostate Gland)
The lumen of the alveoli may contain spherical concentrically lamellated bodies called __.
prostatic concretions or corpora amylacea
- Pea-sized gland inferior to the prostate
- Produces a thick, clear mucus
- Cleanses the urethra of acidic urine
- Serves as a lubricant during sexual intercourse
- Secreted into the penile urethra
Bulbourethral Glands
- Also known as Cowper’s glands.
- Pair of small, compound, tubulo-alveolar glands embedded in the urogenital diaphragm.
- The glands secrete an alkaline fluid and mucous which probably serves as a lubricant.
- Their ducts enter the membranous urethra.
- Its excretory ducts are lined by pseudostratified epithelium.
- In the enlarged alveoli, the cells are flattened; but if the alveoli are empty, the cells are cuboidal or columnar.
Bulbourethral Glands
(Development of the Male External Genitalia)
Mesenchymal cells migrate around the cloacal membrane to form a pair of slightly elevated folds, the cloacal folds. These folds unite to form the __.
genital tubercle
(Development of the Male External Genitalia)
Under the influence of androgens secreted by the fetal testis, there is rapid elongation of the genital tubercle which is now called the phallus. As it elongates, it pulls with it the urethral fold forward to form the urethral groove, the floor of which is known as the __.
urethral plate
(Development of the Male External Genitalia)
At the end of the 3rd month, the two urethral folds close over the urethral plate forming the penile urethra. The most distal portion of the urethra is formed during the 4th month when ectodermal cells from the tip of the glans penetrate inwards and forms a solid epithelial cord. Later, this cord obtains a lumen forming the definitive __.
external urethral meatus
(Development of the Male External Genitalia)
The genital swellings in male known as scrotal swellings form the __.
scrotum
- Extends from the base of the urinary bladder to the tip of the penis
- Carries both urine and sperm
- Sperm enters from the ejaculatory duct
Urethra
Regions of the urethra
Prostatic urethra –surrounded by prostate
Membranous urethra – from prostatic urethra to penis
Spongy (penile) urethra – runs the length of the penis
- Divided sac of skin outside the abdomen
- Maintains testes at 3°C lower than normal body temperature to protect sperm viability
Scrotum
- Internally there are three areas of spongy erectile tissue around the penile urethra
External Genitalia
- Delivers sperm into the female reproductive tract
- Regions of the penis
- Shaft
- Glans penis (enlarged tip)
- Prepuce (foreskin)
Penis
- Folded cuff of skin around proximal end
- Often removed by circumcision
Prepuce (foreskin)
Anatomy of the Penis
- The penis has paired dorsal corpora cavernosa and a single midline corpus spongiosum, which contains the uretha
- These three bodies are bound together by a tough fibrous connective tissue capsule known as the tunica albuginea, and they are covered by a thin layer of skin that has an unusually rich sensory innervation
- Functions both as a sex organ and as an organ for urine excretion
Anatomy of the Penis (2)
- The cavernous bodies of the penis consist of erectile tissue that grows and becomes rigid when filled with blood
- Helical arteries that drain into a venous plexus bring the cavernous bodies a rich supply of blood
Penis in Sexual Function
- During erection, the blood flow into the venous sinuses is greater than the blood flow out, causing the sinuses to fill with blood and causing tumescence of the organ
- Following a sexual encounter, the blood flow to these sinuses slows and the penis becomes flaccid again
The __ consists of three cylindrical masses of erectile tissue; a pair of corpora cavernosa and an unpaired corpus spongiosum. Each body is surrounded by tunica albuginea. In the corpora cavernosa, the spaces are lined by endothelium which is continuous with the endothelium of the arteries and veins. Partitions called trabulae, consisting of dense fibrous tissue.
penis
- Mixture of sperm and accessory gland secretions
- Advantages of accessory gland secretions
- Fructose provides energy for sperm cells
- Alkalinity of semen helps neutralize the acidic environment of vagina
- Semen inhibits bacterial multiplication
- Elements of semen enhance sperm motility
Semen
- Undescended testis
- Unilateral or bilateral
- Due to abnormal production of androgen or failure of the gubernaculum testis to shorten
Cryptochidism
- Results from incomplete fusion of the urethral folds
- Abnormal openings of urethra along the ventral aspect of the penis
Hypospadias
- The external urethral meatus is found on the dorsal aspect of the penis
Epispadias
- With a karyotype of 47 XXY
- Characterized by infertility, gynecomastia and impaired sexual maturation
Klinefelter’s syndrome