Farm Animal Reproduction

Testes

Produce sperm and testosterone

Epididymis

• Passageway of sperm from testes to vas deferens

• 3 parts: head, body, tail

Vas deferens

Transport sperm from testes to penis (during ejaculation)

Accessory sex glands

Secrete components of seminal fluid

Penis

Fibroelastic or vascular type

Overall functions of the male

• Produce and maintain supply of sperm (spermatogenesis)

• Detect females in estrus (pheromones, visual cues)

• Inseminate females and fertilize the female gamete)

Spermatic cord

Contains vas deferens, pampiniform plexus, and external cremaster muscle nerves

Tunica albuginea

Conmective tissue which holds testis together

Seminiferous tubule

Sperm producing cells— true germinal epithelium

Rete testis

Function in sperm transport from seminiferous tubules- 100 tubules

Caput epididymis

Function in maturation of spermatozoa, fluid absorption

Corpus epididymis

Maturation of spermatozoa

Cauda epididymis

Final maturation and storage, only sperm capable of fertilization

Efferent ducts

6-12 tubules absorb fluid

Scrotum

Protection and temperature regulation

Leydig cells (LC)

Source of testosterone

Mitosis (proliferation)

Spermatogonia undergo multiple divisions to generate a larger number of spermatocytes

Meiosis 1 and 2

Replication of DNA to produce haploid spermatids

Differentiation

No further cell divisions, resulting in a fully differentiated immature sperm (spermatids) that is released into the lumen

Mediastinum

In center of testes, transport spermatozoa from lobules within testes to epididymis

Transport from epididymis to penis

1. Exit epididymis and enter vas deferens

2. Vast deferens becomes urethra once past bladder

3. Pass accessory glands that secrete components of seminal fluid

Accessory glands examples (in chronological order)

Ampullae

Seminal vesicles

Prostate

Cowper’s gland

Penile configuration in body

1. Retained in body until excitation/ejaculation

2. Compressed into sigmoid flexure (s-shaped curve) by the retractor penis muscle

   1. Horses do not have sigmoid flexure

3. At excitation, the retractor penis muscle relaxes to extend penis for mating

Fibroelastic penis

• Fibrous, hard sheath of connective tissue all the way through the penis

• Penis does not expand in diameter during erection, it becomes rigid and extends

• Boar, bull, ram

Vascular penis

• Penis increases in diameter and length when aroused

• “Bells out” to plug cervix of female during ejaculation

• Stallion and men

Flehmen response

• Scent driven stimulation

• Exposure of nasopalatine duct to absorb pheromones

Visual/auditory/tactile stimulation

Animal can be trained to mount live animals or (simulation animal— SA) dummies for breeding and/or collection of semen

Volume and sperm concentration

• Inversely related

• Concentration of semen depends in whether specie is a multiple ovulatory, as well as the complexity of the cervix

Pendulous testes

• Fibroelastic penis with pointed glans in bull and a small projection (filiform appendage) in sheep

Horizontal testes

Vascular penis with belling glans in stallion

Inverted testes

Fibroelastic penis with spiral shaped glans that will lock into sow cervix

Cryptorchidism

Lack of testis descent into scrotum and thus thermoregulation is absent

Common in boars and stallions

Bilateral cryptorchidism

1. Sterile

2. No spermatogenesis

3. Testosterone is produced

Unilateral cryptorchidism

Fertile

Reduced sperm producing capacity

Temperature of testis for spermatogenesis

4-6 degrees celsius less than body temperature

5 factors for testis temp regulation

1. Location: testis are outside and away from the body for air circulation

2. Insulation: thin scrotal skin with subcutaneous fat

3. Sweat glands: For evaporative cooling

4. Tunica dartos muscle: smooth muscle under scrotum that can contract to move testis closer or relax to help testis move away from the body

5. Body supply to testis: warm arterial blood is cooled before entering testis by crossing over cooler veins that are leaving testis

Importance of keeping testis cool

Protect sperm

• The farther from the body, the cooler

• The tail of the epididymis is the coolest

• Elevated temperatures will kill sperm cells

• Typically lower sperm count and motility in very high temperatures