Male Reproductive system. - Biology Of Things

Male reproductive system – a easy understanding.

Consists of four major parts namely:

                                                                   

               1. Pair of testes,
               
            2. Accessory duct,
            
            3. Accessory glands,
               
            4. External genitalia.

Pair of testes:

Function: As primary male sex organs.

Structure: Pair of ovoid bodies.

Shape: Oval in shape

Colour: Pinkish in colour.

Thickness: 2-4 cm.

Each testis weights: 0.35 - 0.5 ounces (10 - 15 grams).

Location: Lying in scrotum region.

Scrotum: It is a loose sac of skin.

Function: provides temperature 2-3 degree Celsius lower than the normal body temperature to produce sperms, since viable sperms are not produced in normal body temperature. Acts as a thermoregulator for spermatogenesis.

Location: hanging outside of the abdominal cavity.

Each testis covered by: A fibrous membrane – Tunica albuginea.

Testis divided by: Septa into 200-250 lobules. Each lobule consists of 2-4 testicular (seminiferous) tubules.

Testicular or seminiferous tubules:

Testicular tubules are highly coiled one.

Function: this highly convoluted tubules forms 80% of the testicular substance are the sites for sperm production.

Seminiferous tubules are surrounded by: Interstitial cells or Leydig cells

Leydig cells or Interstitial cells:

Location: embedded in the soft connective tissue

Nature: endocrine in nature, and characteristics features of testis in mammals.

Secretion: androgens namely testosterone hormone, and other immunologically competent cells are also present.

Stratified epithelium of seminiferous tubules is made of Sertoli cells and Male germ cells.

 

Sertoli cells or Nurse cells:

Shape: elongated and pyramidal.

Function: provides nourishment to sperms till maturation.

Secretion: Inhibin hormone.

Function of Inhibin: Involves in negative feedback control of sperm production.

Male germ cells or spermatogenic cells.

Function: divides meiotically and differentiates to produce spermatozoa.

Accessory Ducts:

Consists of:

                                                                                          

            1. Rete testis,                                       

            2. Vasa efferentia,
            3. Epididymis,
            4. Vas deferens.
                                                                                              

Flow chart of accessory ducts:

 Seminiferous tubules of each lobule converge to form a tubules rectus.

                                                                       
    ↓               

                                                 
 Tubules rectus conveys sperms.

                                                                   
        ↓                          

  
 Sperms reaches the rete testis (It is a tubular structure network on the posterior side of testis).

                                      
         ↓                        

        
 The sperms leave rete testis, through vasa efferentia, it enters epididymis.

 EPIDIDYMIS:

 Function: single, highly coiled tube. It temporarily stores the spermatozoa and they undergo   physiological maturation and acquire increased motility and fertilizing capacity.

                                                                                         

          ↓                          

                                                     
 Epididymis leads to vas deferens.

                                                                        
          ↓                       

                                                 
 Vas deferens joins to seminal vesicle and forms an ejaculatory duct

                                                                       
          ↓                                            

                               
 This duct passes through prostate and opens into the urethra.

 Urethra:

• It is the terminal portion of male reproductive system.
• Used to convey both urine and semen at different times.
• Originates from Urinary bladder.
• Extends through the penis by an external opening called urethral meatus.

         ↓                      

                                                                       
 Finally semen reaches Penis.

Accessory glands.

Includes:

        1. Pair of Seminal vesicles,

                                                    

        2. Pair of Bulbourethral glands (also called Cowper’s gland),

                                                    

        3. Single prostate gland.

Seminal vesicle:

Secretion: Seminal plasma (alkaline fluid).

Seminal Fluid contains: fructose sugar, ascorbic acid, prostaglandins, and a coagulate enzyme called vesiculase.

Function of vesiculase: Enhances sperm motility.

Bulbourethral glands:

It is inferior to prostate gland.

Function: helps in lubrication of penis.

Prostate gland:

Encircles urethra and just below the urinary bladder, and secretes a slightly acidic fluid that contains citrate, several enzymes, and prostate specific antigens.

Semen:

• Also known as seminal fluid.
• It is a milky white fluid.
• It contains sperms, and the seminal plasma (secreted from the seminal vesicles, prostate gland and bulbourethral glands).
• It acts as a transport medium.
• Provides nutrients.
• Contain chemicals that protects and activates sperms.
• It facilitates movement of sperms.

Penis:

• It is the male external genitalia.
• It functions as copulatory organ.
• It is made of a special type of tissue that helps in the erection of penis to facilitate insemination.
• The large enlarged portion (end) called glans penis is covered by a loose fold of skin called   foreskin or prepuce.

Diagrammatic view of Male Reproductive System.