Equine Reproductive Anatomy - Male Flashcards
What is the source and role of GnRH (male)
Hypothalamus
stimulate pituitary to secrete FSH/LH
What is the source and role of FSH (male)
Pituitary
stimulate Sertoli cells to mature sperm
What is the source and role of LH (male)
Pituitary
stimulates leydig cells to release testosterone
What is the source and role of testosterone (male)
Testes (leydig cells) and adrenal glands
stimulate sertoli cells to produce sperm
What is the source and role of oestrogen (male)
Testes (leydig cells)
regulation of laminal fluid
Are males seasonal breeders
Yes - long day breeder
sperm production all year but quantity/quality poor
Describe testes morphology
- ovoid shape
- sit in inguinal region horizontally
- 10cm length average
Describe testicular development
- start in abdomen and decend into scrotal position
- right decends first
Why is it important to check if testes descended
problem when one is retained in abdomen
need lower temperature for sperm to survive, too hot at body temperature in abdomen
maintain at 35-36 celcius
Cryptorchid and rig
= one testes decended and one inside retained testicle
abdominal pressure doesnt push testes down through ingunor canal
= castrated one testicle, one remain
How to check if testes descended/are there
feel for testicle
test testosterone levels
HCG test
blood test for oestrogen sulfate in leydig cells (oestrogen higher in stallion)
What is the HCG stimulation test
inject horse with human chorionic gonadotropin
high level = stallion with testes
low level = no testes
What is androgen-binding hormone
glycoprotein produced by sertoli cells and binds to testosterone. keeps testosterone at elevated level in seminiferous tubule
What temperature should testes maintained and how adapted to do so
30.5-32.5 celcius
external location close to body wall
scrotal skin - contains sweat gland to aid temp regulation
What is the tunica dartos, cremaster muscle and pampiniform plexus
lining of muscle within the scrotum which contracts (testes closer to abdomen, reduce scrotal surface and heat loss) and relaxes to temperature regulation
moves testes up/down/sideways also for temp reg and protection
formed by dense cappilary network where arterial and venous supplies come into close contact
- warm blood enter testes by artery loses heat to cooler venous return
Where and how testes suspended
from abdominal cavity wall by spermatic cord which contains blood vessels, nerves and ductus deferens
What is the ductus deferens
transports sperm from testes through penis
between epididymus and urethra (through spermatic cord, abdomen and ampulla
What is pampiniform plexus
site where artery and vein intertwine
temp reg = form of heat
at the most cranial aspect of testes
What is the tunica albuginea
- lobes
fibrous layer that arises from peritoneum covering spermatic cord, testes and epididymis
provide support to suspended testes
- sheets of tunica albugina divide into lobes
- each lobe is mass of convoluted seminiferous tubules with intertubular areas
- each area responsible for oneof 2 functions ~ gameotogenic (sertoli cells and SemT) or ~ steroidogenic (leydig cells and intertubual tissue)
Describe the testes internaly
composed of semineferous tubules
embedded with supportive tissue (leydig cells)
semineferous tubules lined with sertoli cells where spermatogenesis occurs
Claudin 11 in spermatogenesis
expresed by sertoli cells
role = tight junction formation in the testis, helps the sertoli cells for the blood testis barrier, if absent stops spermatogenesis progressing past meiosis and leads to infertility
What is the epididymis
seminiferous tubules empty into it lies dorsally over testes cylindrical 70cm Caput(head)/Corpus(body)/Cauda(tail) surrounded by muscle to aid sperm movement
What is the urethra and corpus spongeosum
excretory canal for urine and semen
surrounded by striated muscle - contracts during ejaculation
surrounded by corpus spongiosum (spongy tissue that aids erection)
urethra opens within urethral fossa at the end of glans penis w/urethral process projecting beyond glans
What are the seminal vesicles
- lie adjacent to neck of bladder
- add seminal plasma and nutrients to semen via urethra ~ (SP) high conc of potassium, citric acid and gel
- volume of secretion depends on testosterone cocs
- 15-20cm long 5cm wide
What is the prostate
- bilobed structure with single exit to urethra
- situated between bulbourethral glands and ampulla
- H-shaped gland
- produces alkaline secretion to buffer acidic urine before and during ejaculation
What are the Bulbourethral glands
- lie either side of urethra near ischial arch
- secrete pre-ejaculatory fluid to flush urethra of urine and bacteria and thick mucous (lubrication)
- contain lots of fibrous connective tissue
Penis - physical structure
- cylindrical, muscular
- extends from ischial arch of pelvis to the umbilicus
root body and shaft - resting = lies retracted within prepuse and held by retractor muscle
- 50cm length and 2.5-5cm diameter (not erect)
- many sebaceous glands within folds of prepuce - build up of smegma
Penis - root
- attatched to pelvis via ischiocavernous muscles
- bulbospongious muscle covers root and ventrally w/in penis around urethra
Penis - body
- composed mostly corpus cavernosum - spongy tissue that becomes engorged (swell with blood)
- corpus spongiosum - spongy tissue that surrounds urethra (also engorges), surrounded by bulbospongious muscle ~ contained w/in tunica albugina
- contains erectile tissue
- haemodynamic = responds to blood pressure
What is the glans penis
What is strange about the retractor muscle in stallions
enlarged free end of penis, filled with nerve endings and where fossa glandis located
under-developed
ventral to bulbospongiosus muscle
What cell no. increases during breeding season and why
role of sertoli cells
setoli cells becuase increase in seminiferous tubule length
- aid sperm development
- form blood testis barrier (claudin 11)
- phagocytic (digest degenerating germinal cells
- secrete luminal fluid and proteins
Where is sperm stored
- cauda epidydimis
- if not passed up vas deferens as result of ejaculation, degenerate and absorbed overtime = allow fresh supply of sperm available
What are the vas deferens
= connects epidydimis to urethra, passing the accessory glans and into penis
- thick muscular wall w/ 3 layers ~ inner oblique ~ middle circular ~ outer longitudinal = propell sperm and surrounding fluid by peristalsis (wave muscle contractions)
- lumen = small and folded ~ maximise surface area aiding sperm storage and reabsorption of testicular fluids
What is the ampulla glands and why important
- glands paired outfoldings of vas deferens where meets the urethra
- secretions high in ergothionine = antioxidising agent that cleans up toxic by-products of sperm metabolism
What is seminal plasma and role
= major fluid fraction of semen
- provision of energy and protection of sperm form changes of pH, osmotic pressure and oxidisation
- contains gel which forms partial clot in semen
What are accessory glands
4 glands
- bulbourethral
- seminal vesicles
- prostate
- ampulla
primarily responsible for secretion of seminal plasma
What is prepuse and retractor muscle
= double folded covering to penis
- w/in inner fold lies glans end penis
- runs along bottom of penis
- contraction returns penis to prepuse
