This document describes the anatomy and function of the male reproductive system in bulls. It details the structures involved in sperm production (testes, epididymis), maturation (epididymis), storage (epididymis, seminal vesicles), and delivery (vas deferens, penis). Sperm production occurs in the seminiferous tubules of the testes at a rate of 1-25 billion sperm per day. The epididymis is where sperm mature and are stored until ejaculation, with the tail containing 10-50 billion sperm. Upon sexual stimulation, smooth muscle contractions propel the sperm through the vas deferens and out of the penis.

1. Animal/Dairy Science 434
Male Reproductive Tract Anatomy

2. Learning Objectives
• To be able to describe the male
reproductive system in the bull.
– Structure
– Function

3. Factory
• 1-25 X 109
sperm/day
• “Plant” must be air
conditioned
Factory
• 1-25 X 109
sperm/day
• “Plant” must be air
conditioned
Warehouse and Delivery
• Storage 10-50 X 109
sperm
• Sperm for 5-10 ejaculates
• Smooth muscle contractions
upon sexual stimulation
Warehouse and Delivery
• Storage 10-50 X 109
sperm
• Sperm for 5-10 ejaculates
• Smooth muscle contractions
upon sexual stimulation
Finishing School
• Fluid Absorption
• 8-25 X 109
sperm
– membrane changes
– nuclear & flagellar
stabilization
– motility, fertility
– cytoplasmic droplet
translocation
Finishing School
• Fluid Absorption
• 8-25 X 109
sperm
– membrane changes
– nuclear & flagellar
stabilization
– motility, fertility
– cytoplasmic droplet
translocation
Delivery System
• Erection
• Protrusion
• Ejaculation
Delivery System
• Erection
• Protrusion
• Ejaculation
Alterations &
Packaging
• Metabolic substrates
• Surface coatings
• Transport for sperm
Alterations &
Packaging
• Metabolic substrates
• Surface coatings
• Transport for sperm
Testis Epididymis
Tail of Epididymis
Accessory Sex Glands
Penis

4. Bull Reproductive Tract

5. Reproductiv
e Organs of
the Bull

6. Reproductiv
e Organs of
the Bull
Testis
Primary Sex Organ

7. Bull
Testis

8. Bull Tract
Scrotum
• Thermosensor
• Radiator
• Protective sac

9. Bull Tract
Cross Section
Longitudinal Section

10. Scrotal Cross Section

11. Scrotal
Longitudina
l
Section

12. Structure of
the Testis
Rete Testis
(within the mediastinum)
Tunica Albuginea
Seminiferous Tubule

13. The Testis
Mediastinum
Seminiferous
Tubule
Rete Testis

14. Structure of
the Testis
Rete Testis
(within the mediastinum)
Tunica Albuginea
Seminiferous Tubule

15. Structure of
the Testis
Vas Efferentia
6-12 tubules
Caput Epididymis
Cauda Epididymis
Corpus
Epididymis
Vas Deferens
Spermatic Cord
• Vasectomy
Secondary Sex Organs

16. Structure of
the Testis
Rete Testis
(within the mediastinum)
Tunica Albuginea
Vas Efferentia
6-12 tubules
Caput Epididymis
Cauda Epididymis
Corpus
Epididymis
Seminiferous Tubule
Vas Deferens
Spermatic Cord
• Vasectomy

17. Pampiniform
Plexus
Testicular
Artery
Spermatic
Chord
Pampiniform Plexus
• Counter Current Exchange
 39° C - 34° C
 70 ng T/ml - 4.8 ng T/ml
• Vascular, lymphatic and nerves
• Heat exchanger
• Houses cremaster muscle

18. Testis Arterial
Pulse
Spermatic
Artery
Testicular
Artery
Pampiniform
Plexus
Testicular
Artery

19. Spermatic Chord
Pampiniform
Plexus

20. Bull Tract
Tunica Dartos

21. Contraction of the Tunica
Dartos
Tunica Dartos
• Smooth muscle
• Androgen
dependent
(Testosterone)
Testis

22. Bull Tract
Gubernaculum

23. Bull Tract
Pelvic Genitalia

24. Pelvic Genitalia of the Bull
Pelvic Urethra
Muscle

25. Bull

26. Bulb of the Penis

27. Reproductiv
e Organs of
the Bull
Cowpers
Gland
Caput Epididymis
Cauda EpididymisTestis
Scrotum
Glans
Penis
Bladder
Ampulla
Seminal
Vesicles
Prostate
Rectum
Vas Deferens
Gubernaculum
Sigmoid
Flexure
Retractor
Penis
Muscle

28. Cross Section of Bull Penis

29. Penis Cross Section

30. Glans Penis of the Bull
Free Part
of Penis
Glans PenisRaphe
Urethral Process
Prepuce (Retracted)

31. Glans Penis
Free Part
of Penis
Glans Penis Raphe
Urethral
Process
Prepuce (Retracted)

32. Arterial Supply

33. Reproductiv
e Organs of
the Bull
Cowpers
Gland
Caput Epididymis
Cauda EpididymisTestis
Scrotum
Glans
Penis
Bladder
Ampulla
Seminal
Vesicles
Prostate
Rectum
Vas Deferens
Gubernaculum
Sigmoid
Flexure
Retractor
Penis
Muscle
Prepuce