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ANSC4045 - week 2
farm animal repro - male repro
| Term | Definition |
|---|---|
| spermatic cord | • location of spermatogenesis • extends from body cavity into scrotum; pathway for blood, lymph, nerves |
| testis | • male gonad; production of sperm + endocrine function (testosterone production) |
| epididymus | • location of storage + final maturation of sperm |
| accessory sex glands | • produce seminal plasma --> volume + metabolic function of semen |
| penis | • copulatory organ |
| cremaster muscle | • supports testis and aids in temperature control • striated muscle; continuous with internal abdominal oblique muscle |
| fibroelastic penis | • seen in the bull, boar, and ram • limited erectile tissue encased in dense connective tissue • sigmoid flexure allows retraction inside the body; extends to lengthen penis during erection - no change in diameter |
| vascular penis | • seen in the stallion • penis made of highly flexible tissue that fills with blood during erection, increasing in size and firmness |
| reason for testicular temperature control methods | • in mammals, testis must be 4 to 6 degrees C cooler than body for successful spermatogenesis |
| pampiniform plexus | • vascular structure providing countercurrent heat exchange between the body and the testis • heat from arterial blood entering the testis is transferred to cooler venous blood exiting the testis |
| exchange of testosterone in the pampiniform plexus | • testosterone levels up to 10x higher in venous blood exiting the testis vs. arterial blood entering the testis • concentration gradient means some testosterone re-enters arterial flow back into the testis |
| pulse pressure | • difference between systolic (beat) vs. diastolic (relax) blood pressures |
| mean arterial pressure | • average systolic + diastolic blood pressures |
| pulse pressure elimination in the pampiniform plexus | • blood pressure is maintained between inguinal canal + testicular surface with no systolic/diastolic difference |
| contractions of the cremaster muscle | • rhythmic contraction + relaxation facilitates blood flow through the pampiniform plexus • striated muscle --> contractions are not long-term --> only minor role in controlling testicular temperature • ram + bull: promoted by sexual arousal |
| scrotum | • thermosensor, radiator, protective sac • skin heavily populated with sweat glands innervated by sympathetic nerves • thermosensitive nerves affect sweating + respiration |
| four major layers of the scrotum | 1. skin 2. tunica dartos 3. scrotal fascia 4. parietal tunica vaginalis |
| tunica dartos | • smooth muscle layer just beneath scrotal skin; responds to scrotal skin temperature • sustained contractions hold testis close to body when cold; when hot, muscle relaxes to increase surface area |
| control of tunica dartos' contractile characteristics | • depends on presence of androgens • castrated males do not have the ability to contract the tunica dartos |
| two layers of the testicular capsule | 1. visceral tunica vaginalis 2. tunica albuginea |
| testicular tunica albuginea | • sends projections into testicular parenchyma that form lobules around the mediastinum • pumping action of smooth muscle move sperm into rete tubules |
| testicular parenchyma | • functional cellular mass • consists of tubular compartment + interstitial compartment |
| tubular compartment of testicular parenchyma | • seminiferous tubules, site of spermatogenesis |
| interstitial compartment of testicular parenchyma | • cells of Leydig, site of testosterone production |
| cells of Leydig | • within interstitial compartment of testicular parenchyma • produce testosterone |
| testicular medistinum | • central connective tissue core • contains rete tubules, which connect to efferent ducts |
| efferent ducts | • lead out of the testis into the epididymal duct |
| seminiferous tubules | • highly convoluted, microscopic tubules that connect to rete tubules • site of spermatogenesis • basement membrane + layer of seminiferous epithelium |
| seminiferous epithelium of the seminiferous tubule | • basal compartment + adluminal compartment • Sertoli cells anchored to basement membrane and surround developing germ cells |
| Sertoli cells | • only somatic cells in seminiferous epithelium • they don't make the sperm, just support them • tight junctions separate basal + adluminal compartments and form blood-testis barrier |
| basal compartment of the seminiferous epithelium | • closer to basement membrane • spermatogonia + early spermatocytes |
| adluminal compartment of the seminiferous epithelium | • primary + secondary spermatocytes, spermatids |
| blood-testis barrier | • prevents immune reaction to haploid germ cells, considered foreign • allows for unique environment within adluminal compartment |
| excurrent duct system | • efferent ducts converge to epididymal duct for transport out of the testis |
| epididymal duct | • highly convoluted duct • length of 30-60 meters • final maturation of spermatozoa + acquisition of motility + fertility (in 1st segment) |
| three regions of epididymis | • head (caput) at the top of the testis • body (corpus) in the middle of the testis • tail (cauda) at the bottom of the testis - sperm spend the most time here in storage |
| sperm characteristics - head (caput) of epididymis | • 8-25 billion spermatozoa • not motile or fertile • proximal cytoplasmic droplet • low disulfide crosslinking |
| sperm characteristics - body (corpus) of epididynus | • 8-25 billion spermatozoa • some motility + fertility • translocating cytoplasmic droplet • moderate-high disulfide crosslinking • can bind to oocytes |
| sperm characteristics - tail (cauda) of epididymus | • 10-50 billion spermatozoa • normal motility + fertility • distal cytoplasmic droplet • high disulfide crosslinking • can bind to oocytes |
| accessory sex glands | • produce seminal plasma, many components have unknown function • ampullae, vesicular glands, prostate gland, bulbourethral glands |
| seminal plasma | • non-cellular fluid vehicle for spermatozoal delivery during copulation |
| ampullae | • enlargements of ductus deferens between the epididymus and pelvic urethra |
| vesicular glands | • paired glands |
| prostate gland | • singular gland |
| bulbourethral glands | • paired glands |
| volume of ejaculate - bull | • 5 mL |
| volume of ejaculate - stallion | • 30-100 mL |
| volume of ejaculate - boar | • up to 200 mL |
| three parts of the penis | 1. base (root) 2. shaft (main portion) 3. glans penis (specialized distal end) |
| glans penis | • specialized end of penis • stimulation is primary factor initiating ejaculation |
| corpus cavernosum | • main area of erectile tissue in the shaft of the penis |
| corpus spongiosum | • another, lesser layer of erectile tissue surrounding the urethra in the penis |
| muscles associated with the penis | 1. urethralis 2. bulbospongiosus 3. ischiocavernosus 4. retractor penis |
Created by:
junoreg
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