Male Reproductive System

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  • Created by: Becca
  • Created on: 30-12-13 12:39
What is the function of the general male reproductive system?
Production/nourishment/temporary storage of haploid male gametes, intromission of spermatozoa suspension into female genital system & poduction of male sex hormones
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What is the individual function of the testes, ductal system, secretory glands & penis?
Testes: production spermatozoa, synthesis & secretion of androgens. Ductal system: carriage of spermatozo to exterior. Secretory glands: provides seminal fluids/nutrients to support/nourish spermaozoa, form bulk of semen. Penis: intromission of semen
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What is the tunica albuginea?
Tunica albuginea (TA) thickens posteriorly to form the mediastinum of the testis. Fibrous septa from TA divides the body of testis into 250-350 lobules, each lobule contains 1 to 4 Seminiferous tubules (80 cm long, 150 micron diameter)
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What are Leydig cells?
Lie in interstitial spaces between seminiferous tubules. Leydig cells have LH receptors. In puberty, stimulation of these receptors leads to synthesis of testosterone and oxytocin which can readily enter the tubules and blood vessels
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What are the two compartments in the testis?
Endocrine & germinal -> Sertoli & Leydig cells respectively
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How do Sertoli cells help to create the blood testis barrier (BTB)?
The tight junctions between adjacent Sertoli cells creates 3 physiologically important tubular compartments for sperm production. These TJs are responsible for creating the blood testis barrier
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What is the function of the basal compartment in sertoli cells?
The area between baso-lateral TJ of Sertoli cells & tunica propria, where spermatogonia reside. The basal compartment is outside the BTB and is accessible to proteins, charged sugars & immune cells
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What is the function of the adlumenal compartment in sertoli cells?
Intercellular space after TJ which isolate it from basal compart. Adlumenal compart ideal for spermatogenesis. Sertoli cells actively secrete molecules here which creates tubular fluid necessary for sperm development creating a niche
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How does the body prevent an immune reaction against its own sperm?
Only unidirectional movement through TJ, allows sperm to enter adlumenal compart but prevents them from leaking back out. If immune response elicited, antibodies against sperm antigens could cause autoimmune inflammation & sub-fertility
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What is spermatogenesis? What are the 3 stages?
The process by which spermatozoa are formed: mitotic proliferation (produces large number cells), meiotic division (generates genetic diversity, halves chromosome no) & cytodifferentiation (packaging of chromosomes for effective delivery to oocyte)
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What happens during spermatocytogenesis & meiosis?
Spermatocytogenesis: at puberty spermatogonia stem cells splits to 1 reserve stem cell (type A dark cell) & 1 cell for differentiation (type A pale cell) which gives rise to type B. Meiosis: type B undergoes maturation to primary spermatocyte
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What happens as the primary spermatocytes are formed?
They replicate their DNA to become 4n (important for genetic recombination). Undergo meiosis again to form secondary spermatocytes (2n) which are attached to cytoplasmic bridges. Meiotic division again to form spermatids (n)
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What happens in spermiogenesis (cytodifferentiation phase)?
Occurs in small hollows in luminal surface of Sertoli cells. Golgi phase: fusion of granules forms acrosomal vesicle. Cap phase: acrosomal vesicle changes shape to enclose ant 1/2 nucleus. Acrosome phase: nucleus elongates, microtubule organisation
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What happens in the maturation phase of spermiogenesis?
Excess cytoplasm is pinched off. Prominent mitochondria appears in neck region. Axonemal complex of tail produced - 2 central microtubules surrounded by a ring of 9 fibres (9+2 arrangement)
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What is the function of Sertoli cells for germinal compartment?
Protective of developing germinal cells, supportive (provision of nutrients to developing germinal cells) & phagocytosis (residual bodies shed by spermatids)
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What is the function of the endocrine part of Sertoli cells (SC)?
Leydig cells produces testosterone, binds to SC receptors & induces receptors for FSH. FSH can now stimulate SC to produce androgen binding protein (ABP) inhibin & activin. ABP carries testosterone in testicular fluid. Inhibin inhibits FSH production
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What is the histology of the rete testis?
Lined with simple cuboidal or low columnar epithelium. Network of channels into which fluid & spermatozoa from seminiferous tubules empty
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What is the histology of the epididymis?
Tall ciliated epithelium, contraction of smooth muscle propel immotile spermatozoa. Non-ciliated cells have microvilli and absorb testicular transport fluid (concentrates sperm) & are involved in phagocytosis
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What is the spermatic cord encased in?
Cremaster muscle. Contains the vas/ductus deferens which contains the sperm & specialised vasculature where veins form a pampiniform plexus around the testicular artery
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What is the structure of the vas/ductus deferens?
3 muscle layers (outer/central/inner) & fibro-elastic lamina propria. Peristalsis propels immotile spermatozoa. Can store here for 2-3 days. In absence of ***********, spematozoa dribble through the terminal ampulla & urethra, washed away by urine
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What is the seminal vesicle?
Vast surface area created by folds. Secretes seminal fluid rich in fructose/prostaglandins (contraction of smooth muscle)/proteins/alkaline secretions (neutralise acidic ******)/fibrinogen (clotting). Secretion propelled into ejaculatory duct
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What is the prostate gland?
Collection of concentric secreting glands, open into urethra. Glands lined with stratified columnar to cuboidal epithelia in folds/papillary ingrowths
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What is the bulbourethral gland?
Opens into the membranous urethra. Produces watery fluid rich in galactose & sialic acid. Acts as lubricant and neutralises acidic urine in urethra and vaginal fluids. Precedes semen during emission
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What does the erectile tissue of the peins contain?
2 dorsal cylinders = corpora cavernosa, and 1 ventral cylinder = corpus spongiosum, contains penile urethra
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What is the blood supply to the corpora cavernosa?
Arteries: Internal pudendal artery, dorsal artery to penis, central deep artery. Venous drainage: emissary veins, deep dorsal vein. Anastomosis between central artery & deep dorsal vein (arterio-venous anastomosis)
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What is the physiology of the flaccid penis?
Sinusoidal smooth muscles contract and blood flows from the internal pudendal arteries via cavernosal and helicine arteries to lacunar spaces and out through the open emissary veins. Low volume, low pressure (AV anastomosis helps shunt blood)
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What is the physiology of the erect penis?
Closure of arterio-venous shunts, more blood flows into helicine arteries which straighten. Smooth muscle relax, blood flows to lacunar spaces. Resultant pressure compresses the emissary veins, reducing venous outflow. High volume, high pressure
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Card 2

Front

What is the individual function of the testes, ductal system, secretory glands & penis?

Back

Testes: production spermatozoa, synthesis & secretion of androgens. Ductal system: carriage of spermatozo to exterior. Secretory glands: provides seminal fluids/nutrients to support/nourish spermaozoa, form bulk of semen. Penis: intromission of semen

Card 3

Front

What is the tunica albuginea?

Back

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Card 4

Front

What are Leydig cells?

Back

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Card 5

Front

What are the two compartments in the testis?

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