Learning Objectives

Describe the histological organization of the testis and the process of spermatogenesis in the germinal epithelium the the seminiferous tubule.Contrast spermatogenesis from spermiogenesis.Draw a sperm cell and label its major parts.Explain the prestige of each section of the duct system and also accessory glands that the masculine reproductive tract.Explain the structural and also functional significance of the blood-testis barrier.Describe the framework and function of the prostate gland.Recognize some crucial pathological examples related come the tubes and glands that the masculine reproductive system.

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Keywords

testisexcretory duct systemaccessory gland sementunica albugineatunica vascularissepta seminiferous tubulegerminal epitheliumSertoli cabinet blood-testis barrieradluminal compartmentspermatogenic cabinet Leydig (interstitial) cell decision of Reinkespermatogenesisspermatogoniumprimary spermatocyte secondary spermatocyte spermatid spermiogenesis spermatozoanacrosomeflagellum residual bodycapacitationtubulus rectus rete testisductus efferentesductus epididymisepididymis stereociliabasal cellductus deferens ampulla ejaculatory duct urethra seminal vesicle prostate prostatic concretionbulbourethral glandCowper’s glandpenis body cavernosa corpus spongiosum glans penishelicine artery
The male reproductive system, like the internet, deserve to be believed of as a series of tubes. These tubes provide the masculine gametes native their site of manufacturing in the testes to their destination outside the body. The mechanism itself is separated into two unique units:
The testes , located exterior the significant body cavity and housed in the scrotum.The excretory duct mechanism , which transports the sperm native the testes and also whose accessory glands produce and also modify the components of semen .

Testes


Like the ovaries, the testes room a resource of gametes and steroid sex hormones. Every testis is a compound tubular gland included within the tunica albuginea , a special connective organization coat that contains myofibroblasts the rhythmically contract, and also the tunica vascularis , a very vascular region. The gland is divided into lobules by slim septa the radiate outwards native the dorsal part of the tunica albuginea. Every of these lobules contains between one and also four seminiferous tubules , which room the site of sperm production.The testes contain several crucial cell types that are vital to understand. The first two of these are discovered in the germinal epithelium , the class of the seminiferous tubule in i beg your pardon gamete production and advance occurs:
Sertoli cells extend from the basement membrane of the germinal epithelium to the lumen the the tubule. These cells envelope the emerging sperm cells. They room joined to one an additional by junctional complexes and type the blood-testis barrier . This barrier separates the germinal epithelium into a basal compartment , include Sertoli cells and also diploid germ cabinet precursors, and also an adluminal compartment , which has the commodities of meiosis.Spermatogenic cells encompass each of the stages between the spermatogonium and the mature spermatozoan. This cells show up in layers the represent proceeding stages in their differentiation, with the the very least mature cells near the basal great of the epithelium and the many mature cells close to the luminal layer.Leydig (interstitial) cells are situated within the loosened connective tissue neighboring the seminiferous tubules. They show up pale due to their high cholesterol content and often save on computer crystals of Reinke , which have actually an unknown function. Leydig cells create testosterone in an answer to leutinizing hormone released by the pituitary gland. Testosterone is responsible for male an additional sexual characteristics and the maintain of the germinal epithelium.

Spermatogenesis


The advancement of a maturation sperm cell takes place in 2 steps, spermatogenesis and spermiogenesis.Spermatogenesis is the process by i beg your pardon a spermatogonium establishes into a spermatid. Throughout this process, the variety of chromosomes is halved with meiosis. It involves the following stages:
Spermatogonia rest on the basement membrane the the seminiferous tubule and also divide mitotically to produce much more spermatogonia and also primary spermatocytes. The spermatogonia continue to be in the basal compartment while the spermatocytes are situated in the adluminal compartment.Primary spermatocytes are located in the middle an ar of the seminiferous tubule, in ~ the adluminal compartment. This cells have actually a lengthy prophase that gives rise to the an initial meiotic division.Secondary spermatocytes space the product that the very first meiotic division. They have actually 23 pairs of chromatids. This phase is short-lived and also ends v the 2nd meiotic division.Spermatids space the haploid commodities of meiosis. They remain associated to one one more by cytoplasmic bridges. This bridges an outcome from incomplete cytokinesis and permit for synchronous maturation.
Spermiogenesis is the process by i m sorry a spermatid matures right into a spermatozoan . This procedure involves several steps:
The acrosome , containing hydrolytic enzymes, develops and also comes to overlie the dense, elongated nucleus.A flagellum grows out of the pole the contrary the acrosome, encountering the tubular lumen. This flagellum is a modified cilium that creates from the centrioles the the spermatid.Mitochondria come to be arranged around the flagellum.The mass of the cytoplasm is actors off together a residual body , leaving only a thin rim the cytoplasm roughly the nucleus. Sertoli cells consume the residual body.
The last maturation that sperm wake up in the epididymis, whereby the cells get the capacity to move. They acquire the capacity to fertilize the egg through the procedure of capacitation , which wake up in the female reproductive tract.
Each seiminiferous tubule has a brief terminal segment lined by Sertoli cells that transitions come the tubulus rectus and rete testis . This tubes room lined through cuboidal epithelial cells that bear cilia. They turn into the ductus efferentes , which arise from the dorsal part of each testis and also fuse to kind the ductus epididymis . The epithelium of this pipe is lined by alternate columnar and also cuboidal cells, which give it a scalloped appearance.
These extra-testicular duct system brings the spermatozoa indigenous the testes come the outside of the body. This system is created of several distinctive tubes:
The epididymis is a muscular, convoluted tubule the stores spermatozoa and also is the website at which they acquire their motility. That is lined by a pseudostratified epithelium whose cells contain non-motile stereocilia . This stereocilia absorb lot of the excess liquid containing the spermatozoa. The epithelium that the epididymis additionally contains mitotic basal cell . The ductus deferens is another muscular tubule the carries sperm downstream from the epididymis. Its wall surface is thicker 보다 that the the epididymis and also contains 3 muscular layers: inside longitudinal, center circular, and also outer longitudinal. The epithelium of the ductus deferens is comparable to that of the epididymis, through pseudostratified cell bearing stereocilia. The ampulla the the ductus deferens receive secretions from the seminal veiscles. The ejaculatory duct extends native the ampulla of the epididymis come the urethra. The initial section of the duct has the exact same pseudostratified columnar epithelium as the vault tubes. Close to its termination, the is inside wall by transitional epithelium.The urethra is lined mainly by stratified or psueodstratified columnar epithelial cells, yet its opening display screens a stratified squamous epithelium.

Accessory Glands of the male Reproductive System


The masculine reproductive system includes several accessory glands that contribute to the composition of semen:
The seminal vesicles room glandular sacs that empty right into the ampulla the the ductus deferens. They develop a secretion that makes up end 80% that the seminal fluid and contains fructose, fibrinogen, and also prostaglandins. The pseudostratified epithelial cells appear foamy because of the lipid droplets lock contain, and also the muscular wall surface of the vesicles consists of inner circular and outer longitudinal layers that contract in response to forgiveness stimulation during ejaculation.The prostate is a walnut-sized conglomeration the tubulo-acinar glands the surrounds the early segment the the urethra. This gland produce a secretory product include citric acid and also proteolytic enzymes that prevent coagulation of semen. The prostate often has prostatic concretions in the acinar lumina.The bulbourethral glands , or Cowper’s glands , empty into the urethra and also secrete a lubricating fluid. Their secretory cells and duct contain small mucoid droplets.

Penis


The corpus cavernosa space two columns the erectile tissue located on the dorsal side of the penis. The body spongiosum is a single column of erectile tissue located on the ventral side of the penis. It has the penile urethra and expands distally into the glans penis.
The erectile organization of the penis appears as a substantial sponge-like device of rarely often, rarely vascular spaces intercalated between the arteries and also veins. These sinuses obtain blood from the helicine arteries , i beg your pardon dilate during erection come engorge the sinuses with blood. This, in turn, restricts venous outflow.The skin extending the penis is thin and also contains an plentiful subcutaneous layer v smooth muscle however no adipose tissue. The glans dick lacks hair follicles and also contains only tiny sweat glands.

Pre-Lab Quiz

In a slide reflecting the advancement of sperm in the germinal epithelium, which stage would girlfriend not suppose to see and why?
Answer: You would certainly not suppose to see the secondary spermatocytes since their mitotic department happens an extremely quickly.
Contrast spermatogenesis from spermiogenesis. In ~ what stage perform sperm cells ultimately become completely mature?
Answer: Spermatogenesis is the procedure by which spermatogonia end up being spermatids. Spermiogenesis the procedure by i beg your pardon spermatids become spermatozoa. Sperm obtain motility in the epididymis. Capacitation is the procedure by which spermatozoa come to be motile and also are totally mature; this walk not take place until they are in the female reproductive tract.
Answer: Leydig cells develop testosterone, which is vital for Sertoli cell activity and sperm development. Sertoli cells nourish and support the spermatozoa as they develop.
What is the blood-testis barrier, what 2 compartments does the create, and also what room the cellular materials of every compartment?
Answer: The blood-testis obstacle is produced by tight junctions on adjacent Sertoli cells. The divides the germinal epithelium right into a basal compartment, which consists of spermatogonia, and also an adluminal compartment, which includes spermatocytes, spermatids, and spermatozoa.
Please select whether to view the slides in study setting or quiz mode. In research mode, the pictures will save labels and also a description. In quiz mode, labels and also description will be hidden.
TestisSeminiferous TubulesSpermatogenesisLeydig CellsSertoli CellsSertoli cells EMRete TestisDuctuli EfferentesEpididymisDuctus DeferensUrethraSeminal VesicleProstate GlandPenis

Virtual microscope Slides


Begin by identifying the seminiferous tubules.
This is a cross ar of the epididymis.
Note the heterogeneous epithelium the the prostate and also the abundant stroma consists of smooth muscle and also connective tissue.
Please select whether to watch the slides in study mode or quiz mode. In study mode, the pictures will save labels and also a description. In quiz mode, labels and description will be hidden.

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Quiz

Is this cell on the blood or lumenal side of the testis blood-barrier?
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Answer: the is top top the lumenal next of the barrier. Note the acrosome nearby to the nucleus which suggests this is a spermatid.