1/08/2021

Male reproductive system

 

Introduction: 

  • Reproduction is the ability of individual to produce a new individual, and is considered as one of vital sign of living organisms,

  • Human life starts when a male gamete called “Sperm” fuses with female gamete called “Ovum” to form a single cell called “Zygote”.

  • Male and female reproductive organs are called “Gonads” they are responsible for production of sex hormones and gametes.

Male reproductive system

  • Male reproductive system is divided into internal organs and external organs.

  • External Organs include,

    • Penis.

    • Scrotum.

    • Testes.

  • Internal Organs include,

    • Vas deferens

    • Seminal vesicles

    • Ejaculatory ducts.

    • Prostate gland,

    • Cowper’s Gland (Bulbourethral gland.)

    • Urethra.

Scrotum:

  • It is a muscular sac covered with highly pigmented skin, present behind penis, held hanging between the legs.

  • Scrotum is divided into two compartments by scrotal septum, one houses each testes.

  • The scrotum is supplied with two muscles,

    • Dartos Muscle.

    • Cremaster Muscle.

  • These muscles relax and contract as per body's temperature to keep the temperature of testes 2 to 4 degrees lesser than body temp.

Testes:

  • These are male gonads.

  • They produce male gamete “Sperm” and androgen “Testosterone.”

  • They are “Two” in number, oval in shape and are housed in the each compartment of scrotal sac.

  • Length is 4-5 cm.

  • They are covered with two layers of connective tissues,

    • Tunica vaginalis: Outer.

    • Tunica albuginea: Internal.

  • Tunica albuginea also distributes parts of ovaries in 300 to 400 compartments called “Lobules” by forming curtain-like structures called “Septa”.

  • Each lobules contain “Seminiferous tubules” the site where sperm production takes place.

  • The process of sperm production is called “Spermatogenesis.”

  • Spermatogenesis starts from the basement membrane of seminiferous tubules resulting in maturation of Germ cells to sperms. 

  • In between the developing Germ cells there are some elongated cells called “Sertoli cells” they form a protective”Blood-testis barrier” and also control sperm production by forming a hormone called “Inhibin' '.

  • The formed sperms are then stored in a structure adjoining testes called “Epididymis”, which acts as “Storage and maturation site of sperms

  • During ejaculation the sperms are transferred from epididymis to vas deferens (ductus deferens).

  • Surrounding the seminiferous tubules there are scattered “Leydigs Cells” that secrete male sex hormone “Testosterone”.

Vas deferens:

  • There are two vasa deferentia.

  • Also called “ductus deferens

  • They are thick muscular tubes arising from epidermis and go through the “Inguinal canal” into the pelvic cavity.

  • They can be accessed in scrotum as they form a part of “Spermatic cord”, they can be cut to prevent the transfer of sperms into the semen.

  • The surgical removal of small parts of vas deferens is called as “Vasectomy” and is a “Permanent Sterilization method” for males.

  • Vas deferens ends behind the prostate gland by forming a flask like structure called ampoula which forms “ejaculatory duct” along with seminal vesicle.


Seminal Vesicle:

  • These are slender glandular structures present on either side of the prostate gland.

  • The seminal vesicle along with the ampulla of vas deferens forms a structure called “ejaculatory duct” where sperms coming from vas deferens mixes with secretion of seminal vesicle.

  • Seminal vesicle’s secretion forms 60% of the bulk of Semen (A thick milky white liquid ejaculated by male during sexual intercourse).

  • Secretion of seminal vesicles is rich in fructose which is utilized by sperms as energy source for travel in the female reproductive system.

Prostate Gland:

  • It is a walnut shaped gland located at the base of the urinary bladder.

  • The prostate glands surround a part of urethra called “prostate urethra”.

  • The ejaculatory ducts carrying semen joins urethra in the prostate gland.

  • Prostate glands secrete an alkaline secretion which is essential for,

    • Neutralizing acidity of urethra to protect sperms.

    • Coagulating and decoagulating the semen in female reproductive system (This provides time to the sperms to utilize fructose in semen for further movement)

Bulbourethral Glands:

  • Also called “Cowper’s Glands”.

  • They are situated at the base of the penis and joined to the urethra.

  • They secrete a thick salty secretion that neutralizes the acidic environment of urethra present in penis called “Penile Urethra” and in female vagina.

  • The secretions are secreted just before the ejaculation and also called pre-ejaculate, it doesn't contain sperm but may carry sperms present in urethra.

Penis:

  • The penis is the male organ of copulation (sexual intercourse). 

  • It is flaccid for non-sexual actions, such as urination, and turgid and rod-like with sexual arousal. 

  • When erect, the stiffness of the organ allows it to penetrate into the vagina and deposit semen into the female reproductive tract.

  • Penis consists of a body, glans penis and root. 

  • The body of the penis is made up of three cylindrical masses of erectile tissue.

  • The two lateral masses are called the corpora cavernosa.

  • The smaller middle part which contains the urethra is called corpus spongiosum. 

  • The lower end of the corpus spongiosum is slightly enlarged called the glans penis. 

  • The glans penis is covered with the folded skin called the prepuce (foreskin).

  • An erection and the enlargement of penis are maintained by parasympathetic division of the spinal cord.

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