Understanding anatomy of reproductive system

1. Male reproductive systemMale reproductive system
ByBy
Dr shittu LAJDr shittu LAJ

2. Male reproductive systemMale reproductive system
 External genitaliaExternal genitalia
 Internal genitaliaInternal genitalia

3. Male external genitaliaMale external genitalia
 ScrotumScrotum
 PenisPenis
 urethraurethra

4. Male internal genitaliaMale internal genitalia
The vas deferens,The vas deferens,
Testes (testicles),Testes (testicles),
Urethra,Urethra,
Accessory sex glands, namely the seminal vesicles,Accessory sex glands, namely the seminal vesicles,
the prostrate and the bulbourethral glands,the prostrate and the bulbourethral glands,
Ejaculatory duct.Ejaculatory duct.

6. Male reproductive systemMale reproductive system

7. TestesTestes
Subserves two main functions:Subserves two main functions:
Production ofProduction of male gametes ormale gametes or
spermatozoa, andspermatozoa, and
Endocrine organ- production of maleEndocrine organ- production of male
sexual hormone, testosteronesexual hormone, testosterone, which, which
stimulates the accessory male sexualstimulates the accessory male sexual
organs and causes the development of theorgans and causes the development of the
masculine extragenital sex characteristics.masculine extragenital sex characteristics.

8. The testis is surrounded by a thick capsule, theThe testis is surrounded by a thick capsule, the tunicatunica
albugineaalbuginea..
 The tunica albuginea is covered externally by aThe tunica albuginea is covered externally by a serosaserosa..
 thethe mediastinum testismediastinum testis is ais a conical mass of connectiveconical mass of connective
tissue that projects into the testis and delicate fibrous septatissue that projects into the testis and delicate fibrous septa
radiate from the mediastinum towards the tunica albuginea,radiate from the mediastinum towards the tunica albuginea,
which later divide the parenchyma of the testis into aboutwhich later divide the parenchyma of the testis into about
300300 lobuli testislobuli testis, which communicate peripherally., which communicate peripherally.
 Each lobule contains 1-4Each lobule contains 1-4 convolutedconvoluted seminiferous tubulesseminiferous tubules
(about 150-300 µm in diameter, 30-80 cm long).(about 150-300 µm in diameter, 30-80 cm long).
 Interstitial tissueInterstitial tissue lies the between the convoluted tubuleslies the between the convoluted tubules
and is continuous with a layer of loose vascular connectiveand is continuous with a layer of loose vascular connective
tissue, called thetissue, called the tunica vasculosa testistunica vasculosa testis, which is found, which is found
beneath the tunica albuginea.beneath the tunica albuginea.
 Each seminiferous tubule continues near the mediastinumEach seminiferous tubule continues near the mediastinum
into a straight tubule, ainto a straight tubule, a tubulus rectustubulus rectus. The straight tubules. The straight tubules
continue into thecontinue into the rete testisrete testis, which is a labyrinthine system, which is a labyrinthine system
of cavities in the mediastinum.of cavities in the mediastinum.

9. c/s of a testisc/s of a testis

10. The Convoluted Seminiferous TubulesThe Convoluted Seminiferous Tubules
 Enclosed by a thick basal lamina and surrounded byEnclosed by a thick basal lamina and surrounded by
3-4 layers of smooth muscle cells (or myoid cells).3-4 layers of smooth muscle cells (or myoid cells).
 The tubules are lined withThe tubules are lined with seminiferous epitheliumseminiferous epithelium,,
which consists of two general types of cells:which consists of two general types of cells:
 spermatogenic cells and Sertoli cellsspermatogenic cells and Sertoli cells..

11.  Spermatogenic cellsSpermatogenic cells::
SpermatogoniaSpermatogonia
• Are the first cells of spermatogenesis.Are the first cells of spermatogenesis.
• They originate in the 4th week of foetalThey originate in the 4th week of foetal
development in the endodermal walls of thedevelopment in the endodermal walls of the
yolk sac and migrate to the primordium ofyolk sac and migrate to the primordium of
the testis, where they differentiate intothe testis, where they differentiate into
spermatogonia.spermatogonia.
• Spermatogonia remain dormant untilSpermatogonia remain dormant until
puberty. They are always in contact with thepuberty. They are always in contact with the
basal lamina of the tubule.basal lamina of the tubule.

12. Two types of spermatogoniaTwo types of spermatogonia
• Type A spermatogoniaType A spermatogonia have a rounded nucleus with veryhave a rounded nucleus with very
fine chromatin grains and one or two nucleoli.fine chromatin grains and one or two nucleoli.
• They are stem cells which divide to form newThey are stem cells which divide to form new
generations of both type A and type B spermatogonia.generations of both type A and type B spermatogonia.
• Type B spermatogoniaType B spermatogonia have rounded nuclei withhave rounded nuclei with
chromatin granules of variable size, which often attach tochromatin granules of variable size, which often attach to
the nuclear membrane, and one nucleolus.the nuclear membrane, and one nucleolus.
• Although type B spermatogonia may divide repeatedly,Although type B spermatogonia may divide repeatedly,
they do not function as stem cells and their final mitosisthey do not function as stem cells and their final mitosis
always results in the formation of Primary spermatocytes.always results in the formation of Primary spermatocytes.

13. Primary spermatocytesPrimary spermatocytes
 which lie in the cell layer luminal to the spermatogonia.which lie in the cell layer luminal to the spermatogonia.
They appear larger than spermatogonia.They appear larger than spermatogonia.
 They immediately enter the prophase of the first meioticThey immediately enter the prophase of the first meiotic
division, which is extremely prolonged (about 22 days!).division, which is extremely prolonged (about 22 days!).
 A large number of primary spermatocytes is always visibleA large number of primary spermatocytes is always visible
in cross-sections through seminiferous tubules.in cross-sections through seminiferous tubules.
 Cell divisions, from the formation of primary spermatocytesCell divisions, from the formation of primary spermatocytes
and onwards, to the production of the spermatocytes, areand onwards, to the production of the spermatocytes, are
incomplete.incomplete.
 The cells remain connected by bridges of cytoplasm. TheThe cells remain connected by bridges of cytoplasm. The
completion of the first meiotic division results in thecompletion of the first meiotic division results in the
formation of secondary spermatocytesformation of secondary spermatocytes

14.  Secondary spermatocytesSecondary spermatocytes
• which are smaller than primary spermatocytes. Theywhich are smaller than primary spermatocytes. They
rapidly enter and complete the second meiotic divisionrapidly enter and complete the second meiotic division
and are therefore seldom seen in histologicaland are therefore seldom seen in histological
preparations. Their division results in the formation ofpreparations. Their division results in the formation of
 SpermatidsSpermatids
• which lie in the luminal part of the seminiferouswhich lie in the luminal part of the seminiferous
epithelium. They are small (about 10 µm in diameter)epithelium. They are small (about 10 µm in diameter)
with an initially very light (often eccentric) nucleus. Thewith an initially very light (often eccentric) nucleus. The
chromatin condenses during the maturation of thechromatin condenses during the maturation of the
spermatids into spermatozoa, and the nucleus becomesspermatids into spermatozoa, and the nucleus becomes
smaller and stains darker.smaller and stains darker.
 The terminal phase ofThe terminal phase of spermatogenesisspermatogenesis is calledis called
spermiogenesisspermiogenesis and consists of the differentiation ofand consists of the differentiation of
the newly formed spermatids intothe newly formed spermatids into SpermatozoaSpermatozoa

15.  It takes about 48 days from the time cells enterIt takes about 48 days from the time cells enter
meiosis until morphologically mature spermatozoameiosis until morphologically mature spermatozoa
are formed. Depending on the length ofare formed. Depending on the length of
reproduction of spermatogonia (which is notreproduction of spermatogonia (which is not
precisely determined) it takes approximately 64precisely determined) it takes approximately 64
days to complete spermatogenesis in human.days to complete spermatogenesis in human.
 Roles of pituitary hormones-FSH & LH.Roles of pituitary hormones-FSH & LH.
 Spermatogenesis is regulated by follicle stimulatingSpermatogenesis is regulated by follicle stimulating
hormone (FSH), which in males stimulates thehormone (FSH), which in males stimulates the
spermatogenic epithelium, and luteinizing-hormonespermatogenic epithelium, and luteinizing-hormone
(LH), which in males stimulates testosterone(LH), which in males stimulates testosterone
production by Leydig cells in the interstitial tissueproduction by Leydig cells in the interstitial tissue

16. Sertoli cellsSertoli cells
 Irregular in shape, but mainly columnar.Irregular in shape, but mainly columnar.
 It extends from the basement membrane to the luminalIt extends from the basement membrane to the luminal
surface of the seminiferous epithelium.surface of the seminiferous epithelium.
 The processes of the cells also extend in between theThe processes of the cells also extend in between the
spermatogenic cells.spermatogenic cells.
 The nucleus of Sertoli cells is ovoid or angular, large andThe nucleus of Sertoli cells is ovoid or angular, large and
lightly stained and often contains a large nucleolus.lightly stained and often contains a large nucleolus.
 The Lateral processes of Sertoli cells are interconnected byThe Lateral processes of Sertoli cells are interconnected by
tight junctions, to serve as a structural basis for thetight junctions, to serve as a structural basis for the blood-blood-
testis barriertestis barrier..
 Spermatogonia and primary spermatocytes are located in theSpermatogonia and primary spermatocytes are located in the
basal compartment, while other cellular stages ofbasal compartment, while other cellular stages of
spermatogenesis are located in the adluminal compartmentspermatogenesis are located in the adluminal compartment

17. Functions of sertoli cellsFunctions of sertoli cells
 Provide mechanical support andProvide mechanical support and
 Nutritive support for the spermatogenic cells.Nutritive support for the spermatogenic cells.
 Sertoli cells also secrete two hormones -Sertoli cells also secrete two hormones - inhibininhibin andand
activinactivin - which provide positive and negative- which provide positive and negative
feedback on FSH secretion from the pituitary.feedback on FSH secretion from the pituitary.

18. Internal structure of the testisInternal structure of the testis

19. Interstitial tissuesInterstitial tissues
 Leydig cellsLeydig cells is about 15-20 µm in size.is about 15-20 µm in size.
 located in the interstitial tissue between thelocated in the interstitial tissue between the
convoluted seminiferous tubules.convoluted seminiferous tubules.
 They constitute theThey constitute the endocrine component of theendocrine component of the
testistestis..
 They synthesize and secrete testosteroneThey synthesize and secrete testosterone..
 Leydig cells occur in clusters , which areLeydig cells occur in clusters , which are
variable in size and richly supplied byvariable in size and richly supplied by
capillaries.capillaries.
 The cytoplasm is strongly acidophilic and finelyThe cytoplasm is strongly acidophilic and finely
granular. The nucleus is large, round and oftengranular. The nucleus is large, round and often
located eccentric in the cell.located eccentric in the cell.

20. testistestis

21. The testisThe testis

22. Ducts of the testis & EpididymisDucts of the testis & Epididymis
 Spermatozoa pass via theSpermatozoa pass via the tubuli rectitubuli recti (low columnar(low columnar
epithelium) and theepithelium) and the rete testisrete testis (flattened or cuboidal(flattened or cuboidal
epithelium) into numerousepithelium) into numerous ductuli efferentesductuli efferentes, which, which
are lined by a columnar epithelium, which consistsare lined by a columnar epithelium, which consists
of both absorptive and ciliated cells.of both absorptive and ciliated cells. The height ofThe height of
the two cells types which form the epithelium of thethe two cells types which form the epithelium of the
ductuli efferentes is variable and thus, gives theductuli efferentes is variable and thus, gives the
lumen a characteristic wavy outlinelumen a characteristic wavy outline..
 The ductuli efferentes leave the testis and open intoThe ductuli efferentes leave the testis and open into
a common duct, thea common duct, the ductus epididymidisductus epididymidis (about 6 m(about 6 m
long!).long!).

23. ductus epididymidisductus epididymidis
 Is about 6 m long.Is about 6 m long.
 It is lined by a very tall pseudostratified columnarIt is lined by a very tall pseudostratified columnar
epithelium.epithelium.
 Most cells of the epithelium, also calledMost cells of the epithelium, also called principal cellsprincipal cells,,
have long stereocilia.have long stereocilia.
 Stereocilia are non-motile structures, which in the EMStereocilia are non-motile structures, which in the EM
resemble large microvilli.resemble large microvilli.
 Towards the basal lamina we see a number of small nuclei,Towards the basal lamina we see a number of small nuclei,
which belong to thewhich belong to the basal cellsbasal cells of the ductus epididymidis.of the ductus epididymidis.
These cells regenerate the epithelium.These cells regenerate the epithelium.

24.  Peristaltic contractions of smooth muscle cellsPeristaltic contractions of smooth muscle cells
surrounding the ductus epididymidis move thesurrounding the ductus epididymidis move the
spermatozoa towards thespermatozoa towards the middle segment of themiddle segment of the
duct, which is the site of final functional maturationduct, which is the site of final functional maturation
of the spermatozoaof the spermatozoa - now they are motile.- now they are motile.
 The terminal segment of the ductus epididymidis isThe terminal segment of the ductus epididymidis is
the site of storage of the mature spermatozoathe site of storage of the mature spermatozoa..
 Smooth muscle fibres of the terminal part of theSmooth muscle fibres of the terminal part of the
ductus epididymidis do not contract spontaneously.ductus epididymidis do not contract spontaneously.
 They contract during sexual stimulationThey contract during sexual stimulation
concurrently with the contraction of the musculatureconcurrently with the contraction of the musculature
of the duct into which it opens, the vas deferens.of the duct into which it opens, the vas deferens.

25. The Vas deferens/ ductusThe Vas deferens/ ductus
deferens)deferens)
 TheThe mucosamucosa of the vas deferens forms low longitudinalof the vas deferens forms low longitudinal
folds.folds.
 It is lined by a pseudostratified columnar epithelium.It is lined by a pseudostratified columnar epithelium.
 Similar to the epididymis, cells have long stereocilia.Similar to the epididymis, cells have long stereocilia.
 The lamina propria is unusually rich inThe lamina propria is unusually rich in elastic fibreselastic fibres..
 TheThe muscularismuscularis is well developed (up to 1.5 mm thick) andis well developed (up to 1.5 mm thick) and
consists of a thick circular layer of smooth muscle betweenconsists of a thick circular layer of smooth muscle between
thinner inner and outer longitudinal layers.thinner inner and outer longitudinal layers.
 The muscularis is the structure which makes the vasThe muscularis is the structure which makes the vas
deferens palpable in the spermatic cord.deferens palpable in the spermatic cord.
 The vas deferens is surrounded by an adventitia, which isThe vas deferens is surrounded by an adventitia, which is
slightly denser than usual.slightly denser than usual.

26. epididymisepididymis

27. Male Accessory ReproductiveMale Accessory Reproductive
GlandsGlands
 The accessory (or secondary) male sex glandsThe accessory (or secondary) male sex glands
consist of the following:consist of the following:
 seminal vesicles,seminal vesicles,
 the prostratethe prostrate
 the bulbourethral glandsthe bulbourethral glands

28. The prostateThe prostate
 The prostate is the largest accessory sex gland inThe prostate is the largest accessory sex gland in
men (about 2 × 3 × 4 cm).men (about 2 × 3 × 4 cm).
 It contains 30 - 50 tubuloalveolar glands, whichIt contains 30 - 50 tubuloalveolar glands, which
empty into 15 - 25 independent excretory ducts.empty into 15 - 25 independent excretory ducts.
These ducts open into the urethra.These ducts open into the urethra.
 The glands are embedded into a fibromuscularThe glands are embedded into a fibromuscular
stroma, which mainly consists of smooth musclestroma, which mainly consists of smooth muscle
separated by strands of connective tissue rich inseparated by strands of connective tissue rich in
collagenous and elastic fibrescollagenous and elastic fibres..
 The muscle forms a dense mass around the urethraThe muscle forms a dense mass around the urethra
and beneath the fairly thin capsule of the prostrate.and beneath the fairly thin capsule of the prostrate.

29.  The secretion of the prostate containsThe secretion of the prostate contains citric acid,citric acid,
the enzyme fibrinolysin (liquefies the semen), acidthe enzyme fibrinolysin (liquefies the semen), acid
phosphatasephosphatase, a number of other enzymes and lipids, a number of other enzymes and lipids..
 The secretion of the prostate is the first fraction ofThe secretion of the prostate is the first fraction of
the ejaculate.the ejaculate.
 The secretory ducts of the prostate are lined by aThe secretory ducts of the prostate are lined by a
simple columnar epitheliumsimple columnar epithelium,,
 which later changes to awhich later changes to a transitional epitheliumtransitional epithelium
near the openings of the ducts into the urethra.near the openings of the ducts into the urethra.

30. Seminal vesicleSeminal vesicle
 Seminal vesicles were thought to store semen.Seminal vesicles were thought to store semen.
 They are glands, whose secretion constitutes 60-70They are glands, whose secretion constitutes 60-70
% of the ejaculate.% of the ejaculate.
 This secretory product of the columnar cell, whichThis secretory product of the columnar cell, which
may be seen in the lumen of the seminal vesicles, ismay be seen in the lumen of the seminal vesicles, is
strongly acidophilic.strongly acidophilic.
 It contains large amounts ofIt contains large amounts of fructosefructose which thewhich the
spermatozoa utilise as a source of energy.spermatozoa utilise as a source of energy.
 Furthermore, the secretion containsFurthermore, the secretion contains prostaglandins,prostaglandins,
flavinsflavins (yellow fluorescing pigment - of use in(yellow fluorescing pigment - of use in
forensic medicine to detect semen stains) andforensic medicine to detect semen stains) and
several other proteins and enzymes.several other proteins and enzymes.

31. Seminal vesicleSeminal vesicle
 The cocktail of compounds which is released byThe cocktail of compounds which is released by
the seminal vesicles in addition to fructose hasthe seminal vesicles in addition to fructose has
three main functions:three main functions:
 the formation of thethe formation of the sperm coagulumsperm coagulum,,
 the regulation ofthe regulation of sperm motilitysperm motility andand
 the suppression ofthe suppression of immune functionimmune function in the femalein the female
genital tract.genital tract.
 The secretion of the seminal vesicles is the thirdThe secretion of the seminal vesicles is the third
fraction of the ejaculate (the spermatozoa arefraction of the ejaculate (the spermatozoa are
released with the second fraction - the contents ofreleased with the second fraction - the contents of
the vas deferens).the vas deferens).

32. Histology of Seminal vesicleHistology of Seminal vesicle
 The seminal vesicles develop from theThe seminal vesicles develop from the vasvas
deferensdeferens..
 Their histological organisation resembles toTheir histological organisation resembles to
some extent that of the vas deferens.some extent that of the vas deferens.
 They are elongated sacs (They are elongated sacs (about 4 cm long andabout 4 cm long and
2 cm wide2 cm wide),),
 which taper where they unite with the vaswhich taper where they unite with the vas
deferens. Each seminal vesicle consists ofdeferens. Each seminal vesicle consists of oneone
coiling tube (aboutcoiling tube (about 15cm long15cm long).).

33.  All the lumina seen in sections of the seminalAll the lumina seen in sections of the seminal
vesicle are all in continuity in the intact organ.vesicle are all in continuity in the intact organ.
 TheThe mucosamucosa shows thin, branched, anastomosingshows thin, branched, anastomosing
folds.folds.
 The structure of the epithelium is variable appearingThe structure of the epithelium is variable appearing
columnar or pseudostratified columnarcolumnar or pseudostratified columnar
((columnar cells and basal cells).columnar cells and basal cells).
 The lamina propria of the mucosa is fairly thin andThe lamina propria of the mucosa is fairly thin and
loose.loose.
 TheThe muscularismuscularis consists of inner circular and outerconsists of inner circular and outer
longitudinal layers of smooth muscle.longitudinal layers of smooth muscle.

35. Applied anatomyApplied anatomy