Exam 3 Flashcards
Scrotum
between the hind legs away from the body, pendulous, protects the testes
When do the testes descend
Between the last 30 days of gestation to the first 10 days postpartum
Cryptorchidism (ridgling)
One or both testes do not descend into the scrotum
Why is cryptorchidism undesirable
Most males are castrated and castrating one is very expensive ($2,000)
Bilateral C/R
No testes in the scrotum at all- not fertile
Unilateral C/R
Only one teste descends into the scrotum- still fertile
Testes
Sperm and testosterone production, oval shaped, horizontal orientation
Equine sperm
Tail is offset to one side of the head, swims in large arcs
Epididymis
Sperm maturation and storage, tail of the epididymis is towards the end of the stallion, head is towards head
Pampiniform plexus
Blood comes from an artery coming from the body to the testes and the veins around that artery cool the blood
Tunica dartos
One of the external muscles that goes around the whole scrotum- muscle is temperature dependent
Skin
has temperature sensitive sweat glands to help with evaporative cooling when temp is hot
Cremaster muscle
Not temperature dependent- a fight or flight muscle (sensitive to touch and the enviroment)
Accessory sex glands
ejaculate is a mix of seminal fluid and spermatozoa
Ampulla
two, secretions buffer and protect the sperm
Seminal vesicles
produce post ejaculate, gel fraction (very thick and viscous) gel fraction prevents sperm from getting through from other stallions
Prostate gland
produce post ejaculate, cleanse urethra after sperm has passed
Bulbourethral glands
responsible for producing the pre sperm fraction (cleanses the urethra prior to ejaculation)
Urethra
common passageway for both urine and semen, clean out any smegma one time a year (or bean) (geldings and stallions) if cleaned too often, the beneficial bacteria can be decreased
Smegma
Substance that protects the skin
Sheath
tissue that surrounds the non-erect penis, above prepuce
Prepuce and sheath
protect the penis itself, sheath cleaning
Penis
Musculo cavernosis, delivers ejaculate into cervix, bell shaped
Glands penis
bells out after breeding X4 size (stretches the cervix) causes an oxytocin release in mare to contract and take in ejaculate
Pre sperm fraction
Cleanses urethra (BG)
Sperm rich fraction
(75-95% of sperm) ampulla secretions in here as well
Post sperm fraction or gel fraction
seminal vesicle and prostate secretions
HPT-If given exogenous hormone
leads to less testosterone in testes, and less GnRH, sperm production
Leydig cells
in interstitium (between the tubules) , LH targets cells, cells produce testosterone
Sertoli cells
in seminiferous tubules, FSH targets cells, cells care for developing sperm
What is testosterone vital for
Spermatogenesis and libido
Stallion secondary sex characteristics
- Cresty neck, shiny coat, large jowls, and muscling
Seasonal effects- off season
Libido, sperm production, plasma hormone concentrations, and testicular weight and size is reduced
Spermatogenesis
Production of sperm cells, located in the seminiferous tubules
Blood testes barrier
separates basal and luminal layers, blocks blood from destroying sperm with small chromosome numbers
How long does spermatogenesis take
60 days- one sperm cell from the bottom to reach the top
What is included in spermatogenesis
Spermatocytogenesis, meiosis, spermiogenesis
Order of sperm travel
Seminiferous tubule lumen, rete testis, efferent duct, epididymis, efferent duct, urethra
Mitochondrial sheath in midpiece is important for what
Energy for sperm to move
When do we do a semen evaluation
Every time we collect a stallion
Semen handing
Ejaculate will be damaged in UV light and weather
Semen color
Anything from white to light tan is normal- red could indicate blood in sample
Semen Opacity
Affected by sperm count, the more concentrated, the more opaque
Semen Consistency
Should be watery, if thick there could be gel fraction in sample
Semen contamination
Blood, smegma, and urine
Volume of semen
Start with total- entire ejaculate with all components included
Gel free sample- most important sample
Total minus gel, filtered sample that keeps gel back- in line gel filter keeps sperm cells from mixing with gel
pH testing
Normal 7.2-7.7, with ph meter, abnormally high with contamination or infection
Computer Assisted Sperm Analyzer
Shows motility, morphology, concentration, consistent- used by large stallion centers
I sperm
Mini CASA, Ipad app with kit- motility, morphology, concentration
Primary defects- worst to have
Primarily the result of spermiogenesis gone wrong- head and midpiece
Secondary defects
Tail, have to do with error during storage or handling
Hancock/eosin - nigrosine stain
add semen drop, mix, background will be purple, eosin will stain sperm head pink if damaged, generally heat fix can look at defects now – count 100 cells, then get percent of sperm that is normal
Morphology
used at the beginning of season, then spot check as season goes on (concerns)- see if sperm is being handled correctly
Concentration method 1- Hemocytometer (special slide)
Dilute 1:100 in formalin, can be run on the raw and extended samples, can be used to count doses from straws
Unipette
vial with amount of formalin in bottom, puncture hole in the top and insert the capillary tube with sample into the hole and release