“Male Reproductive System” MHT-CET Class 12 Biology Crash Course| Chapter “Reproduction in Lower & Higher Animals“
In this session Jyoti A. Shete will discuss the theory and MCQ’s of “Male Reproductive System”. The session will be useful for all the aspirants of MHT-CET 2022. The session will be in Marathi and English.
“Male Reproductive System“:-
Human male reproductive system consists of following
- Primary sex organs -Testis
- Accessory organ accessory duct and accessory glands
- External genitalia: Scrotum and Penis
(1) Primary sex organs Testis
- Testes are pair of primary sex organs which are mesodermal in origin.
- They are located outside the abdomen in a pouch called as scrotum extra abdominal in position.
- During early foetal life the taste is developed in abdominal cavity and later the descend into scrotal sac through a passage called inguinal canal
- They are suspended in scrotal sac by spermatic cord is are connected the wall of scrotum by short fibromuscular band called as Gubernaculum.
- They are oval in shape about 4 to 5 cm long 2 to 3 cm wide and 3cm thick
- The outermost covering of the taste is formed the of dense fibrous membrane called as tunica albuginea.
Histology of testis
Externally testes is covered by three layers
- Tunica vaginalis: it is the outermost incomplete peritoneal covering made up of connective tissue and epithelium
- Tunica albuginea: it is middle layer formed by collagenous connective tissue.
- Tunica vasculosa: it is the innermost layer and it is thin and membranous layer.
- Testis divided into about 200 to 300 testicular lobules by fibres from tunica albuginea each lobule has1 to 4 highly coiled seminiferous tubules.
- Seminiferous tubule is internally lined by single layer of cuboidal germinal epithelium cells that is spermatogonium and few large pyramidal cells called as sertoli cells or sustentacular cells or nurse cell.
- Germinal epithelium cells undergoes Spermatogenesis to form spermatozoa
- Sertoli cells provide nutrition to the developing sperm.
- Various stages of sperm at oogenesis can be seen in the seminiferous tubules the innermost spermatogonial cell(2n) primary spermatocytes (2n)secondaryspermatocyte(n), spermatids and sperms.
- Between seminiferous tubules few groups of interstitial cells (leydig cell)are present.
- After puberty interstitial cells produce type of androgen that is testosterone.
- The outermost covering of the testis is formed of dense fibrous membrane called tunica albuginea.
Accessory sex organs:
It includes accessory ducts, accessory glands.
(1) Rete testis: The seminiferous tubules of the testis at the posterior surface form a network of tubules called rete testis. The rete testis open into vasa efferentia.
(2) Vasa efferentia: Vasa efferentia are 12-20 fine tubules arising from the rete testis and join to the epididymis. They carry sperms from the testis and open into epididymis.
(3) Epididymis: It is a long and highly coiled tube which is differentiated into an upper caput-, middle corpus and lower cauda epididymis.The sperms undergo maturation in the epididymis.
(4) Vasa deferens: The vas deferens travels upto the abdominal cavity and loops over the ureter to open into the urethra. Vas deferens joins the seminal vesicle to form ejaculatory duct.
(5) Ejaculatory ducts: The ejaculatory duct passes through the prostate gland and opens into the urethra.
(6) Urethra: The urethra provides a common passage for the urine and semen and hence is also called urinogenital duct.In males the urethra is long and extends through the penis. It opens to the outside by an opening called the urethral meatus or urethral orifice.
(B) Accessory Glands
(1) Seminal vesicles:
- These are a pair of small fibromuscular pouches present on the posterior side of the urinary bladder.
- They secrete a seminal fluid (alkaline) containing citric acid, fructose, fibrinogen and prostaglandins.
- About 60% of the total volume of semen is made up of seminal fluid.
- Fructose provides energy to sperms for swimming, while fibrinogen helps in coagulation of semen after ejaculation for quick propulsion into the vagina.
- The prostaglandins stimulate reverse peristalsis in vagina and uterus aiding faster movement of sperms towards the egg in the female body.
(2) Prostate gland:
- Prostate gland consists of 20 to 30 lobes and is located under the urinary bladder. It surrounds the urethra.
- It releases a milky white, alkaline fluid called prostatic fluid into the urethra.
- Prostatic fluid forms about 30% of the total volume of semen.
- It contains citric acid, acid phosphatase and various other enzymes.
- The acid phosphatase protects the sperm from the acidic environment of the vagina.
(3) Cowper’s glands:
- Cowper’s glands are also known as bulbourethral glands.
- These are pea-sized and lie on either side of membranous urethra.
- They secrete a viscous, alkaline, mucous like fluid which acts as a lubricant during copulation.
Semen:
- It is the viscous, alkaline and milky fluid (pH 7.2 to 7.7) ejaculated by the male reproductive system
- Generally, 2.5 to 40 ml of semen is given out during a single ejaculation and it contains about 400 million sperms.
- Semen contains secretion of the epididymis and the accessory glands for nourishing (fructose), neutralizing acidity (Ca, bicarbonates), activation for movement (prostaglandins).
External genitalia:
(a) Penis:
- The penis is the male copulatory organ.
- It is cylindrical and muscular with three bundles of erectile tissue: a pair of postero-lateral tissue called corpora cavernosa and a median corpus spongiosum. The swollen tip of the penis is called glans penis. It is covered by a loose fold of skin called foreskin or prepuce.
(b) Scrotum:
- It is a loose pouch of pigmented skin lying behind the penis and is divided into a right and left scre sac by a septum of tunica dartos made of smooth muscle fibres. The foetal testes are guided into retained in the scrotum by a short fibro muscular band called gubernaculum. The testes re suspended in scrotum by a spermatic chord.
“Male Reproductive System“:-
Let’s solve the following multiple choice questions………..!
(1) Testis is externally covered by
(A) tunica albuginea
(B) tunicavasculosa
(C) tunicavaginalis
(D) tunica gubernaculum
Ans. (A) tunica albuginea
(2) Outer to the tunica albuginea is an incomplete peritoneal covering called
(A) prepuce
(B) tunicavasculosa
(C) tunicavaginalis
(D) tunica gubernaculum
Ans. (B) tunica vasculosa
(3) Tunica vasculosa is
(A) present inner to tunica albuginea
(B) a thin non-membranous and non-vascular layer
(C) the layer from which fibres divide to formtesticular lobules
(D) present inner to tunica vaginalis
Ans. (D) present inner to tunica vaginalis
(4) Lobules are present in testis.
(A) 50 – 100
(B) 150 – 250
(C) 200 – 300
(D) 350 – 450
Ans. (C) 200 – 300
(5) Each testicular lobule hashighly coiledseminiferous tubule.
(A) 1-4
(B) 5-10
(C) 10-14
(D) 15-20
Ans. (A) 1-4
(6) Each seminiferous tubule is internally lined by
(A) spermatogonia
(B) spermatozoa
(C) spermatocyte
(D) spermatid
Ans. (A) spermatogonia
(7) Scrotum is
(A) A loose pouch of pigmented skin lyingbehind the penis
(B) Divided into a right and left scrotal sac bytunica albuginea
(C)Covered by prepuce
(D) The tip of penis
Ans. (A) a loose pouch of pigmented skin lying behind the penis
(8) Tunicadartos is made of
(A) Skeletal muscles fibres
(B) Smooth muscle fibres
(C) Cardiac muscles fibres
(D) Both skeletal and smooth muscles.
Ans. (B)smooth muscle fibres
(9) Failure of testis to descend from abdomen intoscrotum leads to sterility called
(A) Atresia
(B) Cryptorchidism
(C) Gastrulation
(D) Amniocentesis
Ans. (B) cryptorchidism
(10) Inguinal hernia is the condition in which
(A) Loop of intestine may pass throughinguinal canal into the scrotum.
(B) Testisfail to descend in scrotum
(C) Inguinal canal fails to form
(D) Scrotum fails to descend in abdominalcavity
Ans.(A) loop of intestine may pass through inguinal canal into the scrotum.
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