Learning Reproduction in Farm Animals

02-Male Reproductive Anatomy  
 

LEARNING OBJECTIVES:

Reproductive Organs in the Male:

Male Reproductive Tract

 

 
 Overall functions of the male:

Structure of the Testis:

 Functions of the testis:
  1. Produce Sperm

  2.  

     
     

  3. Transport sperm out of testis

  4.  
     
     
     
     
     
  5. Produce testosterone
  6.  
     
     
     Testosterone functions
     

 

Thermoregulation of the Testis:

Temperatures 3-5°C less than body temperature are required for Spermatogenesis to occur.
 

One major factor is the Scrotum

 2nd Major Factor - Blood supply to testis.

  1. Pampiniform Plexus

  2.  

     
     
     

  3. Convoluted testicular artery on the surface of the testis.

  4.  
 
 

Cryptorchidism - Lack of testis descent into scrotum and thus thermoregulation.

Functions of the Epididymus:

  1. Transport of sperm - 9-11 days in bull

  2.  

     

 Mechanisms
    1. Pressure of new sperm

    2.  
       

       

    3. Regular contraction of smooth muscle

    4.  

       
       

    5. Stimulated contractions of cauda

    6.  

       

 2. Concentration of sperm
     

     
    Mechanism
     
     
    Fluid absorbed in Caput

       
       
 3.  Maturation of sperm in Caput to Corpus region
     
     
    1. Sperm gain ability to be motile and fertilize the oocyte

    2.  

       

    3. Involves biochemical and physical changes to sperm

    4.  
       
       
    5. Controlled by rate of transport through epididymis and epididymal secretions

    6.  
       
       
    7. Epididymal fluid changes

    8.  

       

    Examples of changes sperm undergo:
     
     
    1. Increase in specific gravity
    2.  

    3. Nucleus more condensed and stable

    4.  
       
    5. Increase (-) charge on plasma membrane

    6.  
       
    7. Sperm become less resistant to cold shock

    8.  
       
    9. Migration of cytoplasmic droplet

    10.  
       
 4.  Storage of sperm - Cauda 
     

     

    1. ~70% of sperm in cauda

    2.  

       

    3. 4 days of testicular sperm prod. stored

    4.  

       

    5. Can be stored for several weeks

    6.  

       

    Factors conducive to storage
     
     
    1. Reduced pH

    2.  

       

    3. Low O2 High CO2

    4.  

       

    5. High K:Na ratio

    6.  

       

    7. Low concentrations of energy substrates

    8.  
       
    Other factors related to epididymal function
     
     
    1. Temperature

    2.  
       
       
    3. Testicular androgens

    4.  
       
       
    5. Ejaculation frequency

    6.  
       
       
     

    Sperm Numbers in regions of the male tract (X 109)

     
    Sexually 
    Rested Bull 
    Depleted 
    Bull
    (20 ejac 5 hr) 
    Bull on 
    (6 ejac/wk) 
    Caput
    19.4 
    16.2
    22.6 
    Corpus
    4.7 
    3.0
    5.2 
    Cauda
    37.6 
    13.7
    26.4 
    Vas Deferens & Ampulla
    7.9 
    2.1
    3.3 
     
 
 

Fate of unejaculated sperm

 

Functions of Vas Deferens and Ampulla for transport of sperm

  1. Low level steady contractions of Vas Deferens

  2.  

     

  3. Increased contractions caused by sexual excitement

  4.  

     

  5. Sperm stored in ampulla age rapidly

  6.  
     

Functions of seminal plasma:

  1. Transport media

  2.  

     

  3. Culture media

  4.  
     
  5. Stimulates sperm motility

  6.  
     
     
  7. Retards sperm capacitation

  8.  
     

     

  9. Stimulates sperm transport in female

  10.  
     
 

Sources of seminal plasma:

    1.
     
    2.
     
    3.
     
    4.

    5.

    6.

    7.
     
     

Chemical composition of seminal plasma:

 

Semen and ejaculation characteristics of farm species

 
Cattle 
Dairy 
Beef 
Sheep 
Swine 
Horses 
Volume (ml) 
1-2 
225* - 400 
60* - 100 
Sperm  
concentration (billion/ml)
1.2 
1.0 
3.0 
0.2 
0.15 
Total sperm (billion)
45 
Motile  
Sperm %
70 
65 
75 
60 
70 
Morphologically normal sperm %
80 
80 
90 
60 
70 
pH
6.5-7.0 
6.5-7.0 
5.9-7.3 
6.8-7.3 
6.2-7.8 
 

Bull (Ram)

Stallion Boar

Illustrated Notes

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