Repro 4 Male Anatomy Flashcards
What is the scrotal sac made up of and what does it contain?
Cutaneous sac of skin and superficial fascia (dartos muscle within this) - out pocketing of anterior abdominal wall, developed from labiosacral folds
Contains testes, epididymus and first part of spermatic cord
Why are the testes outside the body?
Optimum temperature for spermatogenesis is below body temperature
What type of tissue are the testes?
Compound tubular gland
What surrounds the testes?
Tunica albuginea - thick fibrous capsule
What is the mediastinum testis?
A network of fibrous connective tissue on the posterior aspect of the testis connecting with the tunica albuginea. Provides a passageway for sperm to enter the duct system
How many lobules are there in each testis and what are they made from?
About 250 pyramid-shaped lobules divided by strong connective tissue septa - the tunica albuginea
What do the lobules in the testes contain?
Between one and four highly convoluted seminiferous tubules
What occurs in the seminiferous tubules?
Spermatogenesis (germ cells)
Androgen (testosterone) production (Sertoli cells)
Describe the histology of the seminiferous tubules.
Lined by complex stratified epithelium - seminiferous epithelium consisting of Sertoli and spermatogenic (germ cells)
Surrounded by a layer of connective tissue with flattened myofibroblasts and an inner basement membrane
Describe the histology of the Sertoli cells.
Fixed to the basement membrane of the seminiferous tubules
The cytoplasm of each cell forms an elaborate system of processes that extend upwards to the luminal surface, surround the spermatogenic cells and fill all the spaces between them. cell boundaries are therefore difficult to see.
Apical region of each cell has complicated recesses into which the heads of sperms appear to be embedded
What are the more numerous cells in the seminiferous tubules?
Germ cells
What is the innervation of the scrotum?
Anterior - Lumbar plexus
Posterior and inferior - sacral plexus
Which spermatogenic cells rest on the basement membrane?
Spermatogonia, the most primitive form of spermatogenic cells. Later stares are located at successively higher levels in the epithelium
What are primary spermatocytes?
Immature spermatid before it has undergone meiosis (2n)
Why are secondary spermatocytes rarely seen in the seminiferous epithelium?
Short half life. Divide rapidly to form spermatids
How do spermatids appear in light microscopy?
Lightly stained nuclei near the lumen of the seminiferous tubule
Why are primary spermatocytes nuclei variable in appearance?
They are at various stages of the first meiotic division?
What are spermatozoa and where are they?
Mature spermatids. Their deeply staining heads appear to be embedded in the cytoplasm of the Sertoli cells and their tails hang into the lumen of the seminiferous tubule
What is spermatogenesis?
The process by which spermatogenic cells undergo cell proliferation and maturation and are transformed over a period of time into spermatozoa. Last around 70 days and involves cellular nuclei and cytoplasmic changes. Early diploid spermatogonia are transformed into haploid spermatozoa
Where are Leydig cells?
Between the seminiferous tubules in loose connective tissue. AKA interstitial cells
Seen in isolated clusters or in rows along small blood vessels
What is the histological appearance of Leydig cells?
Large spherical nuclei (containing small amounts of peripherally located chromatin and one or two prominent nucleoli)
Eosinophilic
Why do Leydig cells interact with the seminiferous tubules?
They are steroidogenic and the androgens produced (testosterone) are key for spermatogenesis to occur
What is oligozoospermia?
A clinical condition where there is an abnormally low number of spermatozoa in the semen
What is azoospermia?
No sperms appear in the ejaculate
What is cryptorchid testis?
Maldescended testis. Spermatogenesis is impaired because of the elevated temperature. The germ cells are absent while the Sertoli and Leydig cells secrete male sex hormones
Associated with an increased incidence of malignant testicular tumours
What is orchitis?
Inflammation of the testis. Occurs in some individuals who suffer from umps after puberty. Results in impaired spermatogenesis, occasionally leading to seminiferous tubule degeneration or at times infertility
How might an absence of germ cells arise?
May be congenital or acquired e.g. drugs, viral infect, irradiation, cryptorchidism
How common are testicular tumours and from where do they usually arise?
Rare, most arise from germ cells with a high degree of malignancy
What is the arterial supply of the testes?
Direct gonadal branches from the abdominal aorta
What is the venous drainage of the testes?
From pampiniform plexus:
R testicular vein -> IVC
L testicular vein -> L renal vein -> IVC
Where does the epididymus lie?
Postero-lateral border of the testis
What do the seminiferous tubules become posteriorly?
Anastomose to form the rate testis
Where is the fluid layer that allows the testes to move freely in the scrotum?
In the cavity of the tunica vaginalis
What is the cremasteric reflex and how might it be evoked?
Stroking of the superior part of the medial thigh evokes elevation of testis on that side by contraction of the cremaster muscle.
Thigh innervated by ilioinguinal nerve L1; genital branch of genitofemoral nerve (L1 and 2) innervates the cremaster muscle -> spinal reflex arc demonstrated.
Which smooth muscle causes the scrotal skin to wrinkle and when might this occur?
Dartos
When exposed to cold temperature
What is the lymphatic drainage of the scrotum?
Superficial inguinal nodes (palpable with pathology
What is the lymphatic drainage of the testes and what risk does this hold?
Paraaortic nodes at transpyloric plane (abdominal so not palpable, only seen on imaging) Can spread to mediastinal and cervical nodes via intrathoracic
Where are the rete testes?
Mediastinum testes
Describe the path of sperm from the seminiferous tubules to the spermatic cord.
Seminferous tubules -> rete testes -> ductuli efferents -> ductus epididymis -> ductus deferens (vas deferens) in the spermatic cord
What are the sections of the epididymus?
Head
Body
Tail
What is the purpose of the epididymus?
Sperm transport, maturation and storage:
Sperm undergo structural maturation and become motile, capabilities that are essential for successful fertilisation
Stored in the tail segment until ejaculation
Describe the ductus deferens.
(vas deferens) a straight muscular tube that emerges from the caudal epididymus (tail). Contained within the spermatic cord and its main function is to transport the sperms rapidly to the prostatic urethra.
How does the vas deferen terminate?
Ampulla and the duct of the seminal vesicle form the ejaculatory duct which opens into the prostatic urethra
Describe the course of the vas deferen.
Traverses inguinal canal, tracks around the pelvic side wall and passes between the bladder and ureter and forms a dilated ampulla
What does the smooth muscle in the walls of the vas deferens do?
Autonomic innervation permits rapid contractions which propel the tubes contents towards the ejaculatory ducts
What happens to the seminal vesicle and ejaculatory duct during contraction of the vas deferens?
dilate to facilitate the entry of sperms and seminal gland secretion into the prostatic urethra
Describe the histology of the ductus epididymus.
Lined by a tall pseudostratified columnar epithelium with tufts of non-motile cytoplasmic processes called stereocilia projecting into the lumen. Near the lumen, the cytoplasm of the tall cells contains occasionally dark-staining granule.
On the inner surface of the basement membrane small basal cells form a discontinuous layer. The outer surface is surrounded by a highly developed network of capillaries and a circular layer of smooth muscle fibres.
Describe the organisation of muscle in the ductus deferens.
Smooth muscle consisting of inner and outer longitudinal layers and an intermediate circular layer
What type of epithelium lines the vas deferens?
pseudostratified columnar with stereo cilia. Lies on a thin lamina propria containing large numbers of elastic fibres
What happens to the vas deferens in a fixed preparation?
The mucous membrane is thrown into numerous folds due to the elastic fibres in the lamina propria
What is present in the spermatic cord?
Vas deferen Pampiniform plexus (most bulky) Testicular and cremasteric arteries Lymphatic vessels Genital branch of the genitofemoral nerve Enclosed by the cremaster muscle
What is the cremaster muscle?
Discontinuous layer of longitudinally-oriented strands of striated muscle originating from the internal oblique muscle and the fascia from the transversalis
What are the other coverings of the spermatic cord and what are their embryological origins?
External spermatic fascia from the aponeurosis of the external oblique muscle
Internal spermatic fascia from transversalis fascia
What is the course of the spermatic cord?
From: Deep inguinal ring, lateral to inferior epigastric vessels
To: Posterior border of testis
Via: Inguinal canal and superficial inguinal ring
What might the result of infection in the epididymus, vas deferens, seminal vesicles or urethra by bacteria be?
Obstruction of the ducts
Pain
General swelling of the structures
Ejaculate contains few or no sperm
What is a hydrocoele?
Serous fluid in the tunica vaginalis
What is a haematocoele?
Blood in the tunica vaginalis
What is a varicocoele?
Varicosities of the pampiniform plexus
What is a spermatocoele?
Retention cyst within the epididymis
What is epididymitis?
Inflammation of the epididymus
What is the difference between a direct and indirect inguinal hernia?
Direct goes straight through the anterior abdominal wall
Indirect travels through the inguinal rings and canal.
Why are hydrocoeles fairly common in new borns?
Failure of the processus vaginalis to close
What is testicular torsion?
Twisting of the spermatic cord. Usually occurs just above the upper pole. Risk of necrosis of the testis due to occlusion of the spermatic artery
What happens to the sperm if a vasectomy has taken place?
Sperm still produced in the testes but broken down by macrophages and reabsorbed into the blood stream
How long does it take for a vasectomy to be effective?
10-20 ejaculations
Which structures contract in peristaltic waves during emission?
Prostate
Seminal vesicles
Vas deferens?
What nerve controls emission?
Sympathetic via hypogastric nerve (L1, L2)
What is the order of secretion of seminal fluid from structures?
Bulbourethral gland
Prostate
Spermatozoa
Seminal vesicles
What determines the functional integrity of the male reproductive glands?
Male sex hormones - androgens eg testosterone
What % of the ejaculate volume is produced in the seminal vesicles?
70%
What are the seminal vesicles?
2 small glands lying posterior to the prostate gland. Consist of a single highly convoluted tube that joins the ampulla of the ductus deferens to form the ejaculatory duct
Describe the lumen of the seminal vesicles.
The mucous membrane forms an elaborate system of thin, branched, anastomosing folds which project into the lumen. The large lumen of the gland contains coagulated secretion
What is the epithelial lining of the seminal vesicle?
The epithelial lining of the mucous membrane varies from simple columnar to pseudo stratified
What surrounds the lamina propria of the seminal vesicles?
The lamina propria is surrounded by a smooth muscle coat divided into an inner circular and a very thin outer longitudinal layer.
Describe the histology of the prostate gland.
Composed of numerous small, compound alveolar glands from which excretory ducts originate and open independently into the prostatic urethra.
Surrounded by a fibro-muscular capsule from which branching septae divide into numerous but separate compound alveolar glands. The septa are characterised by discrete bundles of smooth muscle fibres interweaving with the connective tissue
What proportion of the ejaculate does the prostate provide?
25%
What does the prostate secretion contain?
Prostaglandins
Proteolytic enzymes
Citric acid
Describe the prostate gland epithelia.
Varies from low cuboidal to simple or pseudo stratified columnar and cells have pale-staining cytoplasm.
Rests on a very thin lamina propria
Blebs of secretion may be seen attached to free cell surfaces and are often seen in the lumen of the glands
What is present in the lumens of the prostate gland?
Blebs of secretion
Concentrically lamellated eosinophilic bodies
Prostratic concretions (corpora amylecea) some of which may be calcified
What glands are contained within the urogenital diaphragm?
The bulbourethral gland
What type of gland is the bulbourethral gland histologically?
Contains tubular and alveolar-type glands
What is the function of the bubourethral gland?
Just prior to ejaculation, it produces a clear watery secretion that may lubricate the urethra
Slightly alkaline secretion neutralises the urethra and vagina in ejaculation
What is BPH and what is the cause and symptoms?
Benign prostatic hyperplasia
Sex hormone dependent
Urinary obstruction and bladder irritation
What factors are implicated in the pathogenesis of prostatic cancer?
Genetic
Hormonal
Environmental
What blood tests are used to assess prostatic disorders?
PSA - prostatic specific antigen produced by normal or abnormal prostatic epithelia
Raised in carcinoma, may not be in BPH
What does a digital rectal examination do?
Allows assessment of the size and consistency of the prostate (posterior)
Where do metastases of prostatic carcinoma tend to travel to?
Internal iliac and sacral nodes via lymph
Vertebrae and brain venous system (internal iliac vein -> plexus in front of vertebral bodies which are valveless (veins of Batson) hence spread of malignancy)
What substances does the seminal vesicle secrete that contributes to semen and what are their function?
Alkaline - neutralise the acidic vagina
Fructose used in ATP production for the sperm
Prostaglandins - Facilitate mobility of the sperm and may promote smooth muscle contraction in the female tract.
Clotting factors, particularly semenogelin - temporarily coagulate semen after ejaculation
What substances does the prostate secrete that contribute to semen and what are their functions?
Milky slightly acidic fluid
Proteolytic enzymes eg PSA and proteolytic enzymes which break down clotting factors from the seminal vesicles hence re-liquifying semen 10-20 mins after ejaculation
Citric acid used by sperm in the krebs cycle for ATP
Acid phosphatase (unknown function)
Approximately what size is the prostate?
3cm (size of a chestnut)
Enlargement of which lobe of the prostate would cause urethral obstruction?
Median
What is the arterial supply to the prostate?
Inferior vesical artery, a branch of the internal iliac artery
Why does cancerous enlargement of the prostate tend to present later than BPH?
Cancerous enlargement is more peripheral than BPH which is closer to the urethra so the urethra is blocked sooner in BPH
How many bodies of erectile tissue are in the penis? Name them.
3 cylindrical bodies:
x2 corpora cavernosa peni (dorsal)
single corpus cavernous urethrae (corpus spongiosum) (ventral)
What is the blood supply to the penis?
Cavernous arteries Branches of the internal pudendal artery: 1. deep arteries 2. dorsal arteries 3. arteries of the bulb
1&2 supply the crura and corpus cavernosa
2&3 supply the bulb and corpus spongiosum
From where does the intern pudendal artery arise?
It is a branch of the anterior division of the internal iliac artery
What is the venous drainage of the penis?
Superficial and deep dorsal veins
What is required to maintain and erection?
Adequate neurological control
Arterial flow
Functioning venous drainage
What are the corpora?
A network-like trabeculae of fibromuscular tissue ramified by cavernous spaces which become filled with blood during erection. In the flaccid condition of the organ the cavernous spaces contain little blood and appear as collapsed irregular clefts
The corpora is surrounded by a thick band of connective tissue
What is the bulbospongiosus and what is its function?
Envelops the bulb of the penis and helps expel the last drops of urine
Helps maintain erections
Where is the ischiocavernosus and what is its function in men?
Muscle just below the surface of the perineum at the crus of the penis
Compresses veins and helps maintain erections
What are the 4 parts of the urethra?
Pre-prostatic
Prostatic
Membranous
Spongy
Which part of the urethra is least distensible and why?
membranous due to the surrounding urethrae muscle and perineal membrane
Name the erectile tissue in the penis.
Corpora cavernosa
Corpus spongiosum
What is the glans penis an extension of?
Corpus spongiosum
Which fibrous capsule surounds the corpus cavernosa?
tunica albuginea
How is an erection formed and maintained?
Vasodilation of the coiled arterioles to the corpora cavernosa increases blood flow.
Tunica albuginea and fascial sheaths are non distensible so corpora cavernosa is rigid, internal pressure rises and occludes venous drainage.
Blood from cavernous spaces drains into the venous plexus then into the deep dorsal vein. This along with increased arterial flow, maintains rigidity of the penis for intercourse
Venous return is also restricted by contraction of the bulbospongiosus and ischiovenous muscles
Why does the corpus spongiosum not become rigid?
Less fibrous and restrictive tunica albuginea. Higher pressure would occlude the urethra and hence prevent ejaculation of the semen
What might happen if the neck of the bladder did not close during ejaculation?
Retrograde ejaculation into the bladder
Which efferent outflow is involved in erection?
Parasympathetic S2-S4 via the inferior hypogastric plexus promotes erection in the erectile tissue through relaxation of smooth muscle in the fibrous trabeculae and coiled arteries
What is the efferent outflow of emission and ejaculation?
Sympathetic L1 and L2
What efferent outflow is involved in depression of erection?
Sympathetic via hypogastric nerve. Increases myogenic tone in arterial smooth muscle
What are some common causes of erectile dysfunction?
Psychological problems
Tear in fibrous capsule of corpus carvernosum
Obstruction of blood flow to corpus cavernosum
Pharmacological
Which part of the penis is removed in circumcision?
Prepuce (foreskin)
What are the potential causes of scrotal swelling?
Haematocoele Hydrocoele Hernia Epididymal cyst Epididymitis Orchitis Spermatocoele Varicocoele Testicular mass (most important) Cyst of the cord
Who is testicular cancer most common in?
19-44 year old men
50% in <35years
How might you discriminate between a hernia and a swelling associated with the testes?
Hernia can be reduced then feel for normal scrotal contents
Why is a varicocoele nearly always on the left?
L testicular vein is almost vertical (drains to L renal vein) so valves have a lot more pressure than those in the oblique R vein (drains to IVC). L valves are therefore more likely to fail with the increased venous weight. R sided varicocoeles are nearly always associated with more serious problems e.g. IVC obstruction
What does a varicocoele feel like on palpation?
A bag of worms
Why might a hydrocoele in young boys increase in size when the patient coughs or cries?
Increased intra abdominal pressure causes more peritoneal fluid to be pushed down through into the scrotum through the communicating tunica vaginalis via the patent processus which is limited in size therefore requires this increase in pressure
What is the difference between an epididymal cyst and a spermatocoele and why does this mean they can be distinguished by trasillumination?
Epididymal cyst arise from unconnected segments of efferent tubules that sprouted from mesonephric ducts and therefore produce clear fluid -> transilluminate well
Spermatocoeles are marginally connected to the rete testis so contains degenerate products of spermatogenesis -> do not transilluminate
Why is NMR very good and palpation poor at assessing lymphatic spread from testicular tumour?
Testicles drain to para-aortic lymph nodes which cannot be palpated until massively enlarged. NMR/CT can detect enlargement <2cm and indicate that XRT or surgical ablation may be beneficial
