1. Lecture 13: Epididymis, Ejaculation and Semen
Animal Science 434
Lecture 13: Epididymis, Ejaculation and Semen

2. Sperm Structure Head Neck Middle Piece Annulus Principal Piece
Acrosome
Neck
Middle
Piece
Annulus
Principal
Piece
End Piece

3. Sperm From Different Species

4. Sperm Head
(Equatorial Segment)
Nucleus
Nucleus

6. Acrosome
Plasma Membrane
Nucleus

7. Acrosin
Hyaluronidase
Acrosome
Nucleus
Plasma
Membrane

8. Laminated columns (flexibility)
Posterior head
Capitulum
Laminated columns (flexibility)
Mitochondrial helix
(energy)
Middle
piece
Axoneme
( )
Course outer
fibers

9. Fibrous Sheath or helix
Annulus
Midpiece
Principal
Piece
Fibrous
Sheath or helix

11. Axoneme
Middle Piece
Principal Piece

12. Axoneme

13. Microtubule Sliding in Sperm Tail

14. Sperm Metabolism Glucose Hexokinase Glucose-6-phosphate Anerobic
phosphatase
Hexokinase
Glucose-6-phosphate
Glucose
Phosphohexoisomerase
Anerobic
Metabolism
(Glycolysis)
Fructose-6-phosphate
Fructose
Hexokinase
Lactate + 2 ATP + 2 H2O
Fatty Acids
Aerobic
Metabolism
Tricarboxcylic Acid
Cycle
36 ATP/Glucose
36 ATP/Fructose

15. 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

16. Sperm Metabolism Temperature dependent
ATP production increases as temperature increases
ATP dependent processes are temperature dependent
motility increases with increasing temperature

17. Effect of Temperature on Motility
Velocity (µm/s)
Temperature (C)

18. Transport of Sperm Vas Efferentia fluid flow cilia Caput contractions
Deferens
Rete
Testis
contractions
fluid flow
RT secretion
Corpus
contractions
Seminiferous
Tubule
bulk fluid flow
contractions of of myoid cells
Cauda
contractions

21. Epididymal Function Maturation Concentration change in fertility
develop motility
nuclear condensation
cytoplasmic droplet
Concentration
remove water

22. Epididymal Function Secretion Transport Storage T DHT
energy substrates (GPC, carnitine)
glycoproteins, lipids, enzymes
Transport
smooth muscle contraction
Storage
cauda

23. Hormonal Control of Epididymis
Caput
tubal testosterone
Corpus
tubal dihydrotestosterone (DHT)
vascular testosterone
Cauda
tubal DHT

24. Erection Sensory Psychic Sympathetic relaxation of penile
retractor muscle
Parasympathetic
contraction of
ischiocavernosus
muscle
dilation of
vessels
Inhibit vasoconstriction
engorgement
of corpus
cavernosum
decreased
venous
outflow

25. Emission and Ejaculation
Sensory
Psychic
Parasympathetic
Sympathetic
smooth muscle contraction of
prostate, seminal vesicles,
vas deferens, cauda epididymis,
closure of the sphincter
to the bladder
striated muscle contraction
of ischiocavernosus,
bulbospongiosus,
pelvic urethral
emission
ejaculation

26. Ejaculate Characteristics
Species Time lapse for Composition of
Bull 1 second single fraction
Ram 1 second single fraction
Boar minutes fractionated sperm-free sperm-rich coagulum
Stallion seconds fractionated sperm-free sperm-rich mucus
Human seconds single fraction but coagulated

27. Components of Semen water sperm substrates inorganic salts proteins
fructose
sorbitol
inositol
glycerol phosphatidyl choline (GPC)
citric acid
inorganic salts
sodium, potassium, calcium, magnesium, chloride
proteins

28. Initial Semen Evaluation
color
volume
concentration
motility
viability
morphology

29. Ejaculate Characteristics
Species Ejaculate Sperm Total Sperm % % Volume Conc. (x109) Motile Normal (x109/ml) /Ejaculate
Bull
Ram
Boar
Stallion
Man