20- Male Reproductive System Anatomy
what is unique to feline penises?
penile spines-- fibrous connective tissue that scrape the vagina--> contributed to ovulation 1. testosterone-sensitive 2. bioassay for castration - present when androgens are available - absent when low androgens
what is the blood-testis barreri?
made by junctional complexes between sertoli cells 1. sertoli cell junctional complexes form an "airlock"-like barrier--> escape immune surveillance - they sit in the tubule and are lined up in an array 2. maintains the envrionment in the adluminal space that allows spermatogenesis - excludes haploid cells from immune detection 3. limits the entry of substance produced by the germ cells into the general circulation where they woudl be recognzied as foriegn, thus inducing an immune rection
what is the spermatic cord?
majority of vascular sources feed the testicle are located in this area 1. pampinoform plexus (PP) -- extensive vascular network - thermoregulation - protection - site of castration - site of testicular torsion 2. cremaster muscle - skeletal muscle - outside the spermatic cord - from internal abdominal oblique muscle - can lift testicle up into body wall
what are the comportants of tubules in the testi?
1. adluminal - contains luminal portion of sertoli cells, spermatocytes, spermatids, spermatozoa 2. basal-- basement membrane - contains basal portin of sertoli cells and spermatogeonic and spermatocytes 3. interstitial-- outside tubule - externally surrounds the seminiferous tubules, contains leydig cells
what is the mechanisms of erection?
1. arousal--> increased blood flow to the pudendal arteris 2. blood is shunted to the corpus cavernosum via the deep artery of the penis--> increase arterial blood flow 3. compression of cavernal tissues against the ischium prevent venous outflow - corpus cavernosum becomes compressed preventing venous outflow--> more blood in the penis 4. Tumescence (hardened penis)--overall increase in length and cirumference of the penis or lengthening via simoid flexure straightening 5. increased intracorporeal pressure due to continued engorgement, resulting in axial rigidity of the penis 6. mainteinance of the erection is due to a balance between arterial inflow and venous outflow 1. helicine arteries (helix shaped)--> they straighten out when blood flows through them - helix shape that straightens out during erection 2. NANC-- nonadrenergic noncholinergic neruons - Neurotransmitter is NO - during erection, NO converts GTP to cGMP--> sinudoid smooth muscle relaxes and erection forms - PDE3 causes cGP to become GMP thus stopping erectin - sildenafil (viagra) inhibits PDE3 - overall balance in NO cyclization
what are the unique features of the canine penis?
1. bulbus glandis-- separate type of erectile tissue 2. par longa glandis - erectile tissue arouns gland penia and os penis 3. os penis (baculum) - allow for rigidity so the male can enter the female without full ejaculation - allows them to test if the female will allow him to mount and be able to pull out if she is hostile 4. musculo-cavernous - expands in girth and length during erection More mammals have an os penis than do not
what are the erectile tissues of the horses/
1. corpus cavernosum -- main part of the penis that causes erection - urethra under there 2. corpus spongiosum - surrounds urethra 3. corpis spongiosum glandis-- extension of corpis spongiosum - erects at the end of sex forcing a vacuum suction that encourages sperm into the uterus - they ejacualte directly into uterus - stallion: "belling" or "flowering" 4. urethral process - extends beyong gland penis at time of erection NOTE: the penis gets a belling or flowering shape when they ejaculate (this is the corpis sponsiosium glandis)
what are the types of penises?
1. fibroelastic-- heavy connective tissue surrounding it - ruminant, pigs - does NOT expand - bulls: stored in sigmoid flexus, it can lengthen and project out during erection 2. musculocavernous - length and width expand at time of erection - primate, dog, stallion
what are the accessory glands function? names? what influences them?
1. function-- contributes to ejaculatory fluid 2. vary in size and shape in species 3. influenced by androgens/estrogens secreted by testis 4. ampullae (2), vesicular glands (2), prostate gland (1), bulbourethral glands (2)
what is the sperm transit?
1. made in testicle 2. through urethra by musclar force
what are the function of the scrotium
1. maintains spermatogenic temperatures - 2-3 degrees less than body temp - some species have internal testicles 2. holds the testicles - allow for mobility 3. protection -- not very protective, but somewhat 5. sweat glands important for thermoregulation 6. different orientations for different species - horizontal in cattle, horses verticle, dogs between the two
what controls erection?
1. neurologically-mediated vacsular event - vascular events--> engorgement of the corpus cavernosum of the penis with blood 2. PARASYMPATHETIC 3. proximal to distal 4. deep artery of penis sends off branches that become arterioles that then feed into sinuses
how do bovine, equine and canine internal genitalia vary?
1. number of accessory sex glands - bovine= prostate, seminal vescicles, bulbourethral glands, - canine- prostate - stallion: prostate, bulbourethral gland, ampulla, vesicular glands
what are the structures of the testis?
1. parenchyma - surrounds all the lobules 2. lobules with tubulus in it - sperm produced into lumen of tube - seminiferous tubules -- sperm is being produce ALL along this tubule - tubules make sperm - go into efferent ducts (tubules that have merged) 3. efferent ducts merge to form epididymis 4. mediastinum/ VD testes tubules contortus--> seminiferious tubule--> rete tubules
what are the functional and anatomic components of the male reproductive tract/
1. penis - outside the body wall 2. scrotum/testes - outside the body-- need lower temp to produce sperm - scrotum holds the testes 3. spermatic cord - where testicle and scrotum come up through body wall - pampiniform plexus, vaginal tunics 4. urethra - pelvic and penile 5. accesorry sex glands - species dependnet - dogs only have prostate, cattle have 5 6. spermatogenesis - process of making sperm
What is the function of the testicles?
1. produces testosterone and sperm - involved in libido and sexual behavior (testosterone) 2. contained in scrotum in all domestic species - intra-abdominal in whale, elephant, rhino, pinnipeds 3. size, shape and location varies with species
what are the major parts of the penis?
1. root-- anchored on the pelvis near pubis and pelvic bones of ischmium - crus penis (crura): there are two sides, beginning of erectile tissue anchored at the pelvis - bulb 2. body-- part of penis that is free/ not connected - corpus penis 3. glans-- part of penis NOT in the body - glans penis
what is semen comprised of?
1. seminal plasma - portion of ejaculate contributed by the accessory glands 2. sperm
what are the features of the bovine penia?
1. sigmoid flexure at rest - contraction of retractor penic muscle 2. retractor penis muscles - two - erection and urination causes relaxation - smooth muscle 3. dorsal artery is quite extensive
what are the phases of spermatogenesis?
1. spermatocytognesis - differentiation of diploid to haploid 2. meiosis - reduction to haploid 3. spermiogenesis - differentiation to spermatozoa - reductionism, loss of cytoplasm and organelles NOTE: size of testicles dictates the amount of sperm made (~20 million sperm/ gram testis/ days) duration: 10-14 days but varies species to species
what are the striated extrinsic muscles that hold the penis in place and allow it to function?
1. urethralis muscle 2. retractor penis muscle 3. ischiocavernosus muscle 4. bulbospongiosis muscle 5. ischiourethral muscle 6. cremaster muscle - skeletal muscle from external oblique muscles - pulls testicle in and out of body wall
what are the features of a stallion penis?
1. very long with a separate blood supply - internal pudendle like the dog for proximal - external pudendle for the distal 4. corona glandis - specialized glans penis with fossa glandis 5. fossa glandis - potential space that gets cleaned before mating - can get urethral blockage from smegma (bean) - more common in geldings than stallions -- stallions masturbate and clean it out 6. double prepuce that expands at the time of erection 6. corpus cavernosum 7. corpus spongiosum 8. urethral process 9. corpus spongiosum glandis - same tissue as corpus spongiosum/ extension - at the end of erection this gets expanded - causes distal end of penis to suck air out of vagina and gets semen to ejaculate INTO uterus they get belling or flowering when they ejaculate
what are the clinically relevatn vaginal tunics?
1. visceral vaginal tunics (VVT) - origin: visceral peritoneum - open castration, pvt is incised 2. parietal vaginal tunic (PVT) - origin: parietal peritoneum - closed castraction, pvt is NOT incised
what impacts testicular size?
1. volume of testicular parenchyma 2. breed/ species 3. age 4. nutrition 5. season 6. pathology 7. genetics 8. hemicastration 9. testicular degeneration
what is detumscence?
Loss of an erection. Starts when the proper signal to stop the shunting of blood are initiated - loose NO production, loose arterial inflow into penis, loose compression against base of penis - venous outflow then exceed arterial inflow - the smooth muscle in the trabecular of the corpis cavernosum contract to push blood out
How does spermatogensis progress when looking histoogically?
as you go farther into the lumen, the sperm are more mature
what is unique about canine mating?
canine copulatory "tie"
what is the epididymis?
conduit of sperm leaving the testicle, place for sperm to mature after sperm leaves testicle - sperm is not motile or fertile when they leave the testes - 10-14 days -- head to tail of epididymis--> at that time, they are ejectable, fertile and mobile - 60% total sperm contained (most sperm in body is in the epididymis) - fever can inhibit sperm formation, would take 10-14 days or it to show up again there are 3 part 1. caput (head)-- where the spermatic cord inserts 2. corpus (body) 3. cauda (tail)-- distal
how is the heat exchange mechanism in testicles?
counter current heat exchange - how we maintain the cooler temperature for spermatogensis - blood from testicle is colder then core body temp - cools hot arterial blood as it enter testicle
what is emission?
deposition of seminal fluid into pelvic urethra - erection--> simtulation of penis--> sympathetic reflex causes release of fluids in accessory sex glands into pelivc urethra NOTE: erection= parasympathetic, emission= sympathetic deposition of seminal fluid into the pelvic urethra - sympathetically mediated spinal cord reflex wtih some voluntary control - initated by smooth muscle contraction of the accessory glands, pipdidymia and ductus deference - filling sensation in the urethra initiates ejeculation
what is spermiogenesis? how does it work?
final differentation from "round cell" to terminally differentiated spermatozoa
what is spermatogenesis?
process by which haploid spermatozoa develop from diploid germ cells in the seminiferous teubules of the testis 1. seminierous tubule is a loop and site of sperm production in both direction and from basal to luminal direction - sertoli cells hold seminiferious tubules - diploid on the outside--> haploid in the lumen 2. function: to ensure constant sperm production in males during breeding season
what is ejaculation?
sense of expnansion of pelvis urethra (filling sensation in the urethra)--> sympathetic activation--> ejaculation
what is spermatogenesis versus spermiogenesis?
spermatogenesis - production of sperm spermiogenesis - maturation of sperm
what are the erectile tissues of the penis?
surround the urethra 1. corpus cavernosum (Cc) - surrounded by tunica albuginea and trabeculae - trabeculae extend into the erectile tissue-- matrix that allow for erection 2. corpus spongiosum penis (Cs) - surrounds the urethra 3. bulcospongiosus muscle - radial muscle that surround urethra, helps propel sperm out 4. tunica albuguinea - connective tissue - dense tissue trabecula go into tissue - provides framework for erection
what are the layer of the scrotium?
there are a number of layer 1. tunics-- parietal, visceral 2. scrotal wall 3. spaces between the tunics-- cavity of the vaginal process 4. there are ligaments anchorin them in place - scortal ligament - ligament of the tail of the epididymis - proper ligament of testis
what are phosphodisterase 5 inhibitors?
viagra - tragets the cGMP--> GMP pathway
