deck_695151 Flashcards
Development of the testis
7th week of gestation: Testes form26th week of gestation: Testes descend into scrotum at thru inguinal canal as the gubernaculum shortens
seminal vesicles, ejaculatory duct, excurrent ducts origin
Mesonephric duct
seminiferous tubules, straight tubules, retes testis origin
Indifferent gonads
prostate origin
Primordium in pelvic urethra
Determination of Sex
1) genetic sex - Y chromosome at time of fertilization2) Gonandal sex - activation of SRY gene3) Hormonal sex - leydig cells produce testosterone 5alpha-reductase - DHT • Sertoli cells produce Mullerian-inhibiting factor
Tunica albuginea
thick dense CT capsule covering each testis divides testes into lobules by septa
Tunica vasculosa
inner looser portion of testicular CT capsule w/ blood vessels
Blood supply to testis
Testicular artery • Pampiniform plexus • VeinsVas deferens w/ blood supplyCremasteric mm. w/ blood supplyVast plexus of arteries to cool blood - counter current heat exchange: warmer blood supplying seminiferous tubules passes cooler blood in plexus • Sperm need slightly lower temperatures for motility
pathway for gamete to travel
Seminiferous tubules - Spermatogenesis (meiosis) and spermiogenesis (maturation)Straight tubules – no spermatogonia or spermatocytes -> empty into retes testisRetes testis (in mediastinum) - efferent ductules - epididymus - vas deferens - ejaculatory duct - merge w/ urethra in prostate
Seminiferous tubules
Leydig cellsSpermatogenic cells Peritubular cells Sertoli cells
Sertoli cells
-supporting or sustentacular cells-do not replicate after puberty (G0)-Columnar epithelium-extensive apical and lateral processes that surround spermatogenic cells -> blood-sperm barrier
Luminal vs basal compartment
barrier formed by sertoli cell processesLuminal compartment – meiotic cells, spermatocytes, post-meiotic cells, spermatidsBasal compartment – mitotic cells, spermatogoniaPhysical compartmentalization Permeability barrier
Exocrine and endocrine secretory function of sertoli cells
• Secrete fluid that facilitates passage of maturing sperm along seminiferous tubules• Secrete androgen-binding protein: binds and concentrates testosterone and DHT in luminal compartment essential in sperm dev.• Secrete inhinin: involved in feedback loop that inhibits FSH release from anterior pit.• Secrete plasminogen activator: converts plasminogen to active hormone plasmin• Secrete transferrin: iron transporting protein
Spermatogenic cells
derived from primordial germ cells (yolk sac)• Spermatogonial cells (mitotic) - on basal lamina• Spermatocytes (meiotic) • Spermatids (post meiotic: mature into sperm) - near tubule lumen
Peritubular cells
specialized smooth muscle cell• Propels maturing gametes out of seminiferous epithelium
Leydig cells
interstitial cells - Synthesize and secrete testosterone• Eosinophilic• Numerous lip drops • Lipofuscin pigment• Distinct rod shaped crystals of Reinke• Extensive SER and Mitochondria with tubular cristae
Hormonal regulation of male reproductive function
• Sertoli cells haveFSH receptors• Leydig cells have LH and estradiol receptors• leydig and serotoli cells communicate
Spermatogenesis
- the process by which spermatogonia develop into sperm- Begins shortly before puberty under rising levels of gonadotropins continues for majority of man’s life - mitosis and meiosis- Spermatogonial phase- Spermatocyte phase- Spermatid phase (spermiogenesis
Spermatogonial phase
spermatogonia/stem cells divide by mitosis to replace themselves and provide a population of committed spermatogonia cells that will undergo meiosis• 3 types of spermatogonia (begin as A dark -> pale -> B -> 1° spermatocytes -> meiosis)
Spermatocyte phase
- spermatocytes undergo meiosis to reduce chromosome # and DNA content producing haploid spermatids• Primary spermatocytes (2N4C) undergo meiosis to reduce both the chromosome number and DNA amount - Crossing over and independent assortment insure genetic diversity of gametes• Secondary spermatocytes (1N2C) -> meitosis 2 lasts a few hours -> spermatids (1N1C)
Spermatid phase
Spermatid undergo extensive remodeling as they differentiate into mature sperm -> 4 stages
Acrosomal cap
contains hyaluronidase, neuramidase, acid phosphatase and acrosin• Like a vesicle• Makes zona pellucida of oocyte permeable- Acrosome reaction -> release of acrosomal enzyme occurs as sperm touches egg
Principal piece
approx. 40 picom and contains the axoneme as well as a dense fibrous sheath of proteins that play a role in directing the beat of flagella
Sperm maturation
• Morphological maturation – in seminiferous tubules: mitosis, meiosis and sperm maturation• Functional maturation – in epididymis as sperm gain motility
process of fertilization
• Stabilization of sperm membrane• Capacitation• Binding of sperm to zona pellucida• Acrosome reaction • Sperm moves through zona pellucida - acrosomal enzymes digest a holeflagella propels spermto the oocyte membrane• Binding of sperm to oocyte membrane and enter of sperm nucleus (penetration)• Fertilization – replication and fusion of pronuclei (amphimixis) and first cleavage division (mitosis).
Stabilization
in seminiferous tubules, epididymus and secretion of seminal vessicles- cholesterol and glycoproteins added to sperm plasma membrane
Capacitation
in female tract – cholesterol is removed from sperm plasma membrane and sugar-specific selectins are inserted into the sperm membrane at equatorial region of head
Binding of sperm to zona pellucida
in oviduct as sugar receptors on sperm bind to sugar residues on glycoproteins of zona pellucida
Acrosome reaction
– in oviduct – sperm makes contact w/ zona pellucida• Fusion of acrosomal and plasma membrane occurs and acrosome contents are released near and contacting zona pellucida
Rete Testis
complex series of interconnecting channels w/ highly vascular CT of the mediastinum testis• Simple cuboidal or low columnar• Single apical cilium• Few short microvillisperm from straight tubules -> efferent ductules
Intratesticular Ducts
– seminiferous tubules, tubuli recti/straight tubules and retes testi
Excurrent Duct System
efferent ductules, epididymis, vas deferens, ejaculatory ducts, seminal vesicles
Efferent Ductules
connect rete testis to epidydimus• Pseudostratified columnar epithelium• Alternate b/w tall and short cells saw tooth or festooned appearance• Tall cells – few cilia• Short cells – actively reabsorb fluid secreted by the seminiferous epithelium- Several cell layers of smooth mm cells and interspersed elastic tissue• Ciliary action and smooth mm contraction aid in transport of sperm through efferent d’s
Epididymis
contains the efferent ductules and the duct of the epididymis• Highly coiled• Site of sperm maturation; gain motility and ability to fertilize an oocyte• Androgen dependent• Highly vascular CT and smooth mm covering• Pseudostratified columnar epithelium w/ stereocilia - principle cells: reabsorb fluid; phagocytose residual bodies not removed by sertoli cells and any degraded sperm• First place of male reproductive that lymphocytes appear
Vas Deferens
– longest and thickest portion of the excurrent ducts 3 distinct and thick layers of smooth mm (longitudinal, circular, longitudinal)- Pseudostratified columnar epithelium with sterocillia; basal cells; mucosa thrown into folds b/c of thick muscle layers- Direct continuity with epididymis- Ascends along posterior border of testis close to testicular vessels and nerves- Enters abdomen as part of spermatic cord, passes thru inguinal canal
Accesory sex glands
- Seminal vesicles – secrete a fructose rich fluid; metabolic substances for sperm- Prostate gland (largest male sex gland) – secretes acid phosphatase, fibrinolysin, citric acid and prostate-specific antigen (PSA)- Bulbourethral/ Cowper’s glands – secrete pre-seminal fluid, mucus w/ galactose to lubricate penile urethra
prostate
Parenchyma divided into 4 anotomical zones• Peripheral zone – site of most prostatic carcinoma• Central zone – resistant to inflammation and carcinoma• Transitional zone – mucosal glands; site of BPH - nodular masses compress urethra• Periurethral zone - main site of benign tumor• Glands are highly irregular in shape and lined with variable epithelium• Concretions (diagnostic) calcium carbonate deposites, accumulate w/ age• Stroma is rich in Smooth mm. (diagnostic)
