Good morning students,

Writing an answer is a skill. It should be precise and to the point and must be with all necessary points. The answer should be with proper diagram which is relevant to the answer. Length of an answer never decides the marks given. If it explains everything which has been asked in the question you will be given full marks.

You can label the diagram on both sides. The labels must include all main parts which are described in the answer. 

HUMAN MALE REPRODUCTIVE SYSTEM

It consists of following parts.

     (A) Pair of testes

     1.  A pair of testis is present outside abdominal cavity in thin pouch of skin called scrotum, suspended by spermatic cord.

     2.  Testis are oval in shape.

     3.  Testes are held in position with the help of gubernaculum, short fibromuscular band.

     4.  Functions:

          A)  Primary function of testes is spermatogenesis i.e. development of sperms.

          B)  Testes secrete hormone called as testosterone responsible for development
     of secondary sexual characters in males.

     5.  Testes are considered as primary sex organs in males.

          [Testes descend down into scrotum before birth (7th month of pregnancy),
in some animals like elephant, whale, dolphin testis never descend down. This is called as cryptorchidism].

     (B) Scrotum:

     1.  It is a thin pouch of skin and extra abdominal in position.

     2.  It shows presence of testis, epididymis and testicular end of spermatic cord. Inside it.

     3.  Scrotal sac is divided internally by muscle septum into two compartments of which left scrotal sac is slightly downwards than right scrotal sac.

     4.  Scrotum acts as thermoregulatory and regulates temperature for proper functioning of testis (2-3)0 C less than normal body temperature.

     5.  Scrotum protects testis from mechanical injuries. Cavity of scrotum remains filled up with watery fluid.

     6.  Scrotum is internally lined by dortos tunic muscle which functions according to change in temperature of surroundings.

     (C) Duct System                                                                                      

     Duct system shows presence of different types of ducts which are as follows:

(I)  Vasa efferentia.

     1.  Numerous ducts join together to form a single structure at base of testis

     2.  It carries sperms from testis to epididymis.

(II) Epidydimis.                                                                                            

     1.  It is compact mass of coiled ducts present along margin of each testis.

     2.  It is paired in nature.

     3.  It measures nearly 6m in length when uncoiled, longest duct in male reproductive system.

     4.  It shows presence of three subparts such as head or caput epidydimis,

          Corpus or middle epidydimis and tail or cauda epidydimis.

Functions:                                                                                                   

     (a)  It acts as passage for sperms.

     (b) It stores sperms temporarily

     (c) It provides nourishment to sperms and provides viability.

(III) Vasa differentia:

     1.  These are long muscular tubes originating from caudal epidydimis.

     2.  It measures nearly 30 cm in length.

     3.  Two vasa differentia are supported by arteries and connectives tissues called as inguinal canal.

     4.  It receives duct from seminal vesicle and continues as ejaculatory duct.

     Function: It carries sperms from epidydimis to urethra.                                 

(IV) Urethra:

     1.  Downward extension of urinary bladder is called as urethra.

     2.  It is 15-20 cm in length, passes through penis and runs upto tip of penis.
It opens as urethral opening at tip.

     3.  It is divided into three parts namely prostatic urethra, membranous urethra and penile urethra.

     4.  Functions: Serves as common passage for both urine as well as sperms hence name urinogenital duct.      

     (D) Accessory Sex Glands:-

          Three additional sex glands are present in male reproductive system which are as follows

(I)  Seminal Vesicles.

     1.  Present in pair near urinary bladder

     2.  Glands open into ejaculatory duct.

     3.  Their secretions form major part of semen.

     4.  Secretion is rich in fructose and keeps sperms healthy as well as provide energy.

(II) Prostate Gland:

     1.  It is a multilobulated gland present near proximal part of urethra and opens into prostatic urethra.

     2.  Its secretion is termed as prostatic fluid which contains acid phosphatase.

     3.  Fluid is alkaline in nature and protects sperm from acidic environment of male urethra and vagina of female reproductive system.

     4.  Secretions of Glands are also responsible for increasing motility.

(III) Cowper’s gland/Bulbourethral gland:-

     1.  These are small sized glands present on either sides of urethra.

     2.  Glands open through tiny duct into urethra.

     3.  Glands secrete a sticky substance which lubricates passage during coitus or copulation.

(E) External genitalia or Penis.

          1.  It is cylindrical muscular, erectile organ.

          2.  It consists of root of penis, shaft of penis, glans penis (tip of penis)

          3.  Shaft shows presence of three erectile tissues of which corpora cavernosa
     is paired and corpus spongiosum is unpaired.

          4.  Tissues show rich blood supply and are responsible for erection.

          5.  Corpus spongiosum is slightly expanded and conical part forming glans 
     penis.

          6.  Glans penis shows presence of retractile fold of skin called as prepuce
     or foreskin. [In some animals, penis shown bone called as bacculum]

          Functions:

          1.  It acts as copulatory organ.

          2.  It is responsible for ejaculation of sperms.

          3.  Glans penis helps in stimulation and erection.

 Histology of Testis.

  1.  Externally each testis is covered by three layers namely tunica albuginea,

     tunica vaginalis, tunica vasculosa (outside to inside)

  2.  Internally each testis is divided into lobule by strip of tunica albuginea.

  3.  Each lobule is consisting of coiled structures called as seminiferous tubules.

  4.  Each seminiferous tubule considered as structural and functional unit of testis.

  5. Inner lining of seminiferous tubule is formed by germinal epithelium and subtentacular cells on sertoli cells or nurse cells.

  6.  Germinal epithelial cells show spermatogenesis to produce sperms.

 7. These remain attached to sertoli cells which are few and column like or pyramidal.­

 8.  Sertoli cells provide nourishment to developing sperms hence the name nurse cells.

  9.  Scattered in connective tissue, groups of polyhedral cells are present called  as interstitial cells or leydig’s cells.

  10. These cells are endocrine in nature and are responsible for secretion of  testosterone which brings development of secondary sexual characters in   males.

 11. Thus, testes are dual functioning show spermatogenesis and secrete
     testosterone.

Questions:-

1. Describe human male reproductive system.

2. Describe internal structure of testis.

3. Write a short note on duct system in male reproductive system.

4. Give an account of various types of accessary glands associated with human male reproductive system.

5. Draw a well labelled diagram of human male reproductive system.

6. Draw a well labelled diagram  of  v.s. human testis.

7. Draw a well labelled diagram of t.s. human testis.