Male reproduction 3

• Types of penis

  • fibroelastic penis
  • Musculovascular penis
• fibroelastic penis


  • ram, bull, boar
  • erectile tissue - corpus cavernosum and corpus spongiosum
  • sigmoid flexure - allows penis to be retracted int body until erection
  • Sigmoid flexure held by retractor penis muscles
  • relaxation of retractor penis muscles causes penis to protrude out the prepuce

  
• corpus cavernosum function


  • fills with blood and expands - outer part of penis
• corpus spongiosum function


  • tissue around the penile urethra ( urethra stays open during erection to ejaculate sperm out) - high pressure
  • rigid area of erectile tissue that allows the urethra to stay open
• musculovascular penis 


  • stallion and humans
  • large corpus cavernosum as it fills with blood during erection. - high volume and high pressure
  • no sigmoid flexure- so always protrudes out of body.
  • Corpus cavernosum in this type of penis is much larger to maintain erection - need extreme engourgement.

  
• glands penis (tip)


  • highly specialised between species as it relates to mating strategy and where the sperm is deposited into the female
• tom cat glans penis 


  • barbs on tip - androgen dependent spines - as females are induced ovulators -
  • as penis withdraws the barbs traumatise the female tract and initiate release of egg.
• boar glans penis 


  • corkscrew shaped- spins to screw through cervix and into uterus - ensures large sperm volume is not lost
  • boars have large ejaculate so sperm has to be deposited into the uterus
• ram glans penis 


  • have a urethral process on the tip which at ejaculation thrashes around spraying sperm in a thin layer across the cervix
  • ensures it sticks
• echidna penis 


  • monotreme
  • most primitive living mammal - closest to reptile and similar to reptile penis
  • penis has 4 branches at erection one side of penis retracts and engorgement of the alternative side occurs
  • ejaculation alternates between sides - maintains sperm concentration if interval between mating is brief - mate lots of females in short period of time
• psychogenic stimuli for an erection

  • visual cues
  • mating in others - used in cattle
  • lordosis - in cats
  • olfactory cues
  • sniffing of vulva
  • female urination
  • pheromones
• Erection and ejaculation 


  Erection-

  • stimulation of pelvic nerve
  • Arterial dilation and increased blood flow - to corpus cavernosum and spongiosum
  • Relaxation of retractor penis muscle - straightens sigmoid flexure - penis protrudes from prepuce
  • Muscle of vas deferens, seminal vesicles and prostate contract
  • Spermatozoa and seminal plasma expelled
  • Can be very forceful in some species - stallion and boar
• types of ejaculation

  • single spurt- 1-3 second ejaculation - bulls
  • extended - camel - ejaculates for 6-20 mins
• erection and ejaculation pressure

  • flaccid penis
  • sexual arousal
  • Vasodilation of helicine arteries - inc blood flow
  • Blood flow increases to cavernous tissue and venous outflow decreases
  • Ejaculation occurs
  • Venous outflow and cavernous pressure drops to pre ejaculate pressure

  
• Os penis 


  • bone in penis of canid animals - needed as penis enters female not fully erect.
• erection in dog penis

  • male and female are tied
  • Penis enters female not fully erect as once inside muscles in female vulva contracts
  • Bulbus glandis enlarges as venous outflow is restricted and forms a copulatory lock
• types of semen collection

  • artificial vaginas - used in bulls ,rams and stallions
  • hand collection - in dogs and pigs - pigs require that screwing motion
  • electro ejaculation - low voltage pulses rectally inserted - most get seminal plasma as contraction occurs around tail of epididymis and vas deferens
• copulation in dog

  First stage coitus

  • male mounts female
  • First and second fractions of semen ejaculated
  • lasts 1-2 mins

  The turn

  • dog turn by lifting one leg over the bitch

  Second stage coitus

  • third fraction of semen ejaculated - 30ml
  • 5 - 45 mins lasts for
  • Inter- uterine deposition
  • Still being locked Maintains high vagina pressure - helps force sperm into uterus and increased retention of sperm in female