Animal Science 434 Lecture 13:Epididymis, Ejaculation and Semen

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

Sperm From Different Species

Nucleus Sperm Head Nucleus (Equatorial Segment)

Plasma Membrane Acrosome Nucleus

Acrosome Nucleus Plasma Membrane Acrosin Hyaluronidase

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

Midpiece Annulus Principal Piece Fibrous Sheath or helix

Axoneme Middle Piece Principal Piece

Axoneme

Microtubule Sliding in Sperm Tail

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

Sperm Metabolism Glucose-6-phosphate Anerobic Metabolism (Glycolysis) Fructose-6-phosphate Phosphohexoisomerase Lactate + 2 ATP + 2 H 2 O Tricarboxcylic Acid Cycle Glucose Fructose 36 ATP/Glucose 36 ATP/Fructose Fatty Acids Aerobic Metabolism 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 Motility Velocity (µm/s) Temperature (C)

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

Epididymal Function 1.Maturation –change in fertility –develop motility –nuclear condensation –cytoplasmic droplet 2.Concentration –remove water

Epididymal Function 3. Secretion –T DHT –energy substrates (GPC, free fatty acids, carnitine) –glycoproteins, lipids, enzymes 4. Transport –smooth muscle contraction 5. Storage –cauda

Hormonal Control of Epididymis Caput –tubal testosterone Corpus –tubal dihydrotestosterone (DHT) –vascular testosterone Cauda –tubal DHT –vascular testosterone Absolute need for Androgen

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

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

Ejaculate Characteristics SpeciesTime lapse forComposition of Bull1 secondsingle fraction Ram1 secondsingle fraction Boar minutesfractionated sperm-free sperm-rich coagulum Stallion secondsfractionated sperm-free sperm-rich mucus Human secondssingle 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 Characteristics SpeciesEjaculateSpermTotal Sperm% VolumeConc. (x10 9 ) MotileNormal (x10 9 /ml) /Ejaculate Bull Ram Boar Stallion Man