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Animal Science 434. Lecture 13:Epididymis, Ejaculation and Semen. Head. Sperm Structure. Acrosome. Neck. Middle Piece. Annulus. Principal Piece. End Piece. Sperm From Different Species. Sperm Head. (Equatorial Segment). Nucleus. Nucleus. Acrosome. Plasma Membrane. Nucleus. - PowerPoint PPT Presentation
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Animal Science 434
Lecture 13: Epididymis, Ejaculation and Semen
Head
NeckMiddlePiece
Annulus
PrincipalPiece
End Piece
AcrosomeSperm Structure
Sperm From Different Species
Nucleus
Sperm Head
Nucleus(Equatorial Segment)
Plasma MembraneAcrosome
Nucleus
Acrosome
Nucleus
PlasmaMembrane
•Acrosin•Hyaluronidase
Middlepiece
Laminated columns(flexibility)
Capitulum
Course outerfibers
Mitochondrial helix(energy)
Posterior head
Axoneme(9 + 9 + 2)
MidpieceAnnulus
PrincipalPiece
FibrousSheath or helix
Axoneme
Middle Piece Principal Piece
Axoneme
Microtubule Sliding in Sperm Tail
Sperm MetabolismGlucose-6-phosphate
AnerobicMetabolism(Glycolysis)
Fructose-6-phosphatePhosphohexoisomerase
Lactate + 2 ATP + 2 H2O
Tricarboxcylic AcidCycle
Glucose
Fructose
36 ATP/Glucose36 ATP/Fructose
Fatty AcidsAerobic
Metabolism
Hexokinase
Hexokinase
phosphatase
ATP Utilization in Sperm• motility (60%)• substrate cycling (40%)– wasted
• maintenance of ionic gradients– very small amount
• transcription and translation– none after condensation of nucleus and
loss of residual body
Sperm Metabolism• Temperature dependent– ATP production increases as temperature
increases• ATP dependent processes are
temperature dependent–motility increases with increasing
temperature
Effect of Temperature on MotilityVe
loci
ty (µ
m/s
)
Temperature (C)
Transport of Sperm
Caput
ReteTestis
SeminiferousTubule
VasEfferentia
VasDeferens
Corpus
Cauda
• bulk fluid flow• contractions of
of myoid cells
• fluid flow• RT secretion
• fluid flow• cilia
• contractions
• contractions
• contractions
• contractions
Epididymal Function1. Maturation– change in fertility– develop motility– nuclear condensation– cytoplasmic droplet
2. Concentration– remove water
Epididymal Function3. Secretion– T DHT– energy substrates (GPC, carnitine)– glycoproteins, lipids, enzymes
4. Transport– smooth muscle contraction
5. Storage– cauda
Hormonal Control of Epididymis• Caput– tubal testosterone
• Corpus– tubual dihydrotestosterone (DHT)– vascular testosterone
• Cauda– tubal DHT– vascular testosterone
ErectionSensory
Sympathetic
Inhibit vasoconstriction
relaxation of penileretractor muscle
Parasympathetic
contraction of ischiocavernosus
muscle
decreasedvenousoutflow
dilation ofvessels
engorgementof corpus
cavernosum
Psychic
Emission and EjaculationSensory Psychic
Sympathetic
smooth muscle contraction ofprostate, seminal vesicles,
vas deferens, cauda epididymis,closure of the sphincter
to the bladder
emission
Parasympathetic
striated muscle contractionof ischiocavernosus,
bulbospongiosus,pelvic urethral
ejaculation
Ejaculate CharacteristicsSpecies Time lapse for Composition of
Bull 1 second single fraction
Ram 1 second single fraction
Boar 5 - 25 minutes fractionatedsperm-freesperm-richcoagulum
Stallion 30 - 60 seconds fractionatedsperm-freesperm-rich
mucus
Human 10 - 30 seconds single fraction but coagulated
Components of Semen• water• sperm• substrates– fructose– sorbitol– inositol– glycerol phosphatidyl choline (GPC)– citric acid
• inorganic salts– sodium, potassium, calcium, magnesium, chloride
• proteins
Initial Semen Evaluation• color• volume• concentration• motility• viability• morphology
Ejaculate CharacteristicsSpecies Ejaculate Sperm Total Sperm % %
Volume Conc. (x109) Motile Normal(x109) /Ejaculate
Bull 8.0 1.5 12 75 95
Ram 1.0 3.0 3 95 95
Boar 200 .25 50 70 90
Stallion 80 .15 12 70 40-90
Man 2-6 .15 .9 65 30-70