Gametogenesis- Spermatogenesis

GAMETOGENESIS- SPERMATOGENESIS

Q. 1

Male infertility occurs if the sperm count is less than :

 A

100 mill / ml

 B

75 mill / ml

 C

50 mill / ml

 D

20 mill / ml

Q. 1

Male infertility occurs if the sperm count is less than :

 A

100 mill / ml

 B

75 mill / ml

 C

50 mill / ml

 D

20 mill / ml

Ans. D

Explanation:

20 mill / ml


Q. 2

Spermicidal jelly acts through :

 A

Acrosomal enzyme

 B

Cervical enzyme alteration

 C

Glucose uptake inhibition by sperms

 D

Disruption of cell membrane

Q. 2

Spermicidal jelly acts through :

 A

Acrosomal enzyme

 B

Cervical enzyme alteration

 C

Glucose uptake inhibition by sperms

 D

Disruption of cell membrane

Ans. D

Explanation:

Ans. is d i.e Disruption of cell membrane

Spermicides :

“Spermicides are contraceptive chemical agents. They comprise,of a chemical capable of destroying sperm, incororated into an inert base. The commonly used spermicidal agents contgain nonionic surfactants which alter sperm surface membrane permeability, causing osmotic changes resulting in killing of sperm. Most of the spermicides contain nonoxynol-9 which is the best for this purpose.”


Q. 3

Time taken for spermatogenesis is :

 A

31 days

 B

45 days

 C

61 days

 D

90 days

Q. 3

Time taken for spermatogenesis is :

 A

31 days

 B

45 days

 C

61 days

 D

90 days

Ans. C

Explanation:

61 days


Q. 4

Which of the following does not conduct spermatozoa?

 A

Ampulla of the ductus deferens

 B

Duct of the seminal vesicle

 C

Epididymis

 D

Prostatic Urethra

Q. 4

Which of the following does not conduct spermatozoa?

 A

Ampulla of the ductus deferens

 B

Duct of the seminal vesicle

 C

Epididymis

 D

Prostatic Urethra

Ans. B

Explanation:

The duct of the seminal vesicle carries seminal fluid, a basic fluid containing fructose.
The contents of the seminal fluid buffers the acid in the vagina and provides nutrients for sperm.
The duct of the seminal vesicle joins with the ampulla of the ductus deferens (which is carrying sperm) to form the ejaculatory duct.
This is the first place where seminal fluid mixes with sperm.
Sperms are first formed in the seminiferous tubules.
They then travel from the head to the tail of the epididymis, through the ductus deferens, into the ejaculatory duct where they mix with seminal fluid, into the prostatic urethra, through the rest of the urethra, and then out the penis.
So, all of the other answer choices are places that are important for the passage of sperm.
 
Ref: Hoffman B.L., Schorge J.O., Schaffer J.I., Halvorson L.M., Bradshaw K.D., Cunningham F.G., Calver L.E. (2012). Chapter 19. Evaluation of the Infertile Couple. In B.L. Hoffman, J.O. Schorge, J.I. Schaffer, L.M. Halvorson, K.D. Bradshaw, F.G. Cunningham, L.E. Calver (Eds), Williams Gynecology, 2e.

Q. 5

Which of the following is the correct order of steps of fertilization:

l. Penetration of the zona pellucida
ll. Penetration of the corona radiata
lll. Fusion of the oocyte and sperm cell membranes
 

 A

I,II & III

 B

I,III & II

 C

II,I & III

 D

III,II & I

Q. 5

Which of the following is the correct order of steps of fertilization:

l. Penetration of the zona pellucida
ll. Penetration of the corona radiata
lll. Fusion of the oocyte and sperm cell membranes
 

 A

I,II & III

 B

I,III & II

 C

II,I & III

 D

III,II & I

Ans. C

Explanation:

The phases of fertilization include phase 1, penetration of the corona radiata; phase 2, penetration of the zona pellucida; and phase 3, fusion of the oocyte and sperm cell membranes.
 
Ref: Langman’s embryology 11th edition Chapter 3.

Q. 6

A 35 year old male presents to the urologist for an infertility evaluation. A biopsy of his testis is performed to check sperm production and maturation. A microscopic section reveals only a few germ cells near the basal lamina in the seminiferous tubule. Which of the following cells is the germ cell closest to the basal lamina in the seminiferous tubule?

 A

Primary spermatocyte

 B

Secondary spermatocyte

 C

Spermatid

 D

Spermatogonia

Q. 6

A 35 year old male presents to the urologist for an infertility evaluation. A biopsy of his testis is performed to check sperm production and maturation. A microscopic section reveals only a few germ cells near the basal lamina in the seminiferous tubule. Which of the following cells is the germ cell closest to the basal lamina in the seminiferous tubule?

 A

Primary spermatocyte

 B

Secondary spermatocyte

 C

Spermatid

 D

Spermatogonia

Ans. D

Explanation:

Maturation of germ cells (spermatogenesis) within the seminiferous tubules occurs in a concentric pattern with the less mature spermatogonia near the basal lamina and the mature forms near the tubule center. Spermatogonia are 2N cells and mature into larger primary spermatocytes (4N) . These mature into secondary spermatocytes (2N) , and finally into spermatids (1N) . Spermatids undergo spermatogenesis to become mature spermatozoa . Acrosomes form from the Golgi apparatus and a flagellum forms from microtubules. Unneeded organelles are shed. The seminiferous tubules of a reproductive-age male should exhibit all stages of maturation, with mature flagellated sperm in their centers.

 

 


Q. 7

Where does capacitation of sperms occur in the reproductive tract?

 A

Epididymis

 B

Vas deferens

 C

Vagina

 D

Uterus

Q. 7

Where does capacitation of sperms occur in the reproductive tract?

 A

Epididymis

 B

Vas deferens

 C

Vagina

 D

Uterus

Ans. D

Explanation:

After ejaculation into the female, spermatozoa move up the uterus to the isthmus of the uterine tubes where they slow down and undergo capacitation.  

  • Capacitation involves two components : increasing the motility of spermatozoa and facilitating their preparation for the acrosome reaction. From the isthmuses the capacitated spermatozoa move rapidly to the tubal ampullas, where fertilization takes place.
  • Spermatozoa attain progressive motility in the epidydimis. It involves activation of a unique set of proteins from the CatSper family, which are localized to the principal piece of the sperm tail. 
  • Ejaculation of the spermatozoon involves contractions of the vas deferens mediated in part by P2X receptors, ligand-gated cation channels that respond to ATP.
 
Ref: Ganong’s Review of Medical Physiology, 24th Edition, Chapter 23

 


Q. 8

Spermatogenesis occurs at:

 A

Body temperature

 B

Temperature lower than core body temperature

 C

Temperature higher than core body temperature

 D

Temperature does not play a role

Q. 8

Spermatogenesis occurs at:

 A

Body temperature

 B

Temperature lower than core body temperature

 C

Temperature higher than core body temperature

 D

Temperature does not play a role

Ans. B

Explanation:

Spermatogenesis requires a temperature considerably lower than that of the interior of the body.

Ref: Ganong’s Review of Medical Physiology, 22nd Edition, Page 427; Guyton and Hall – Textbook of Medical Physiology, 10th Edition, Page 920


Q. 9

Where does spermatozoa attain maturity during its passage?

 A

Seminal vesicles

 B

Epididymis

 C

Testes

 D

Prostate

Q. 9

Where does spermatozoa attain maturity during its passage?

 A

Seminal vesicles

 B

Epididymis

 C

Testes

 D

Prostate

Ans. B

Explanation:

While passing through epididymis, sperm become motile and their surfaces and acrosomes undergo final maturation steps. Fluid within the epididymis contains glycolipid decapacitation factors that bind sperm cell membranes and block acrosomal reactions and fertilizing ability until the factors are removed as part of the capacitation process in the female reproductive tract.

 
Ref: Mescher A.L. (2013). Chapter 21. The Male Reproductive System. In A.L. Mescher (Ed), Junqueira’s Basic Histology, 13e.

 


Q. 10

All are contents of spermatic cord except:

 A

Pampiniform plexus

 B

Ilio- inguinal nerve

 C

Genital branch of genitofemoral nerve

 D

Cremasteric arteriesSympathetic plexus

Q. 10

All are contents of spermatic cord except:

 A

Pampiniform plexus

 B

Ilio- inguinal nerve

 C

Genital branch of genitofemoral nerve

 D

Cremasteric arteriesSympathetic plexus

Ans. B

Explanation:

B i.e., Ilio – inguinal nerve


Q. 11

All are component of Spermatic cord except :

 A

Pauparts ligament

 B

Genito-femoral nerve

 C

Vas deferens

 D

Pampiniform plexus

Q. 11

All are component of Spermatic cord except :

 A

Pauparts ligament

 B

Genito-femoral nerve

 C

Vas deferens

 D

Pampiniform plexus

Ans. A

Explanation:

A i.e. Pauparts ligament


Q. 12

Which of the following is the correct order of pathway for a sperm

 A

Straight tubules -4 Rete testis -s Efferent  tubules

 B

Rete tubules –> Efferent tubules –> Straight tubules

 C

Efferent tubule Rete testis -> Straight

 D

Straight tubule –> Efferent tubules–>Rete tubules

Q. 12

Which of the following is the correct order of pathway for a sperm

 A

Straight tubules -4 Rete testis -s Efferent  tubules

 B

Rete tubules –> Efferent tubules –> Straight tubules

 C

Efferent tubule Rete testis -> Straight

 D

Straight tubule –> Efferent tubules–>Rete tubules

Ans. A

Explanation:

A i.e., Straight tubules -> Rete testes -> Efferent tubule 

The correct sequence of sperm movement from within testis to urethra is Seminiferous tubule -> Straight tubule (Tubulirecti) -* Rete testes -> Efferent tubule        Epidydimis-> Vas (ductus) deferens-> Ejaculatory duct-> Prostatic urethra


Q. 13

Length of a mature human spermatozoon is‑

 A

50-60 microns

 B

10-40 microns

 C

100-200 microns

 D

300-500 microns

Q. 13

Length of a mature human spermatozoon is‑

 A

50-60 microns

 B

10-40 microns

 C

100-200 microns

 D

300-500 microns

Ans. A

Explanation:

A i.e. 50- 60 microns


Q. 14

Meiosis in spermatogenesis occurs in which of the following step?

 A

Primary spermatocyte to intermediate spermatocyte 

 B

Primary spermatocyte to secondary spermatocyte

 C

Secondary spermatocyte to round spermatid

 D

Round spermatid to elongated spermatid

Q. 14

Meiosis in spermatogenesis occurs in which of the following step?

 A

Primary spermatocyte to intermediate spermatocyte 

 B

Primary spermatocyte to secondary spermatocyte

 C

Secondary spermatocyte to round spermatid

 D

Round spermatid to elongated spermatid

Ans. B

Explanation:

B i.e. Primary spermato cyte to secondary spermatocyte


Q. 15

Spermatogenesis occurs at :

 A

Body temperature

 B

Temperature lower than core body temperature

 C

Temperature higher than core body temperature

 D

Temperature does not play a role

Q. 15

Spermatogenesis occurs at :

 A

Body temperature

 B

Temperature lower than core body temperature

 C

Temperature higher than core body temperature

 D

Temperature does not play a role

Ans. B

Explanation:

B i.e. Temperature lower than core body temperature


Q. 16

Capacitance of sperms takes place in:

 A

Seminiferous tubules

 B

Epididymis

 C

Vas deference

 D

Uterus

Q. 16

Capacitance of sperms takes place in:

 A

Seminiferous tubules

 B

Epididymis

 C

Vas deference

 D

Uterus

Ans. D

Explanation:

D i.e. Uterus

  • Spermatogenesis occurs in germinal epithelium of seminiferous tubulesQ
  • Epididymis reabsorbs 99% of testicular fluid and concentrates and stores spermatozoaQ. After a 18-24 hour stay in epididymis sperms develop the capability of motilityQ which is important for fertilization in vivo. But fertilization occurs in vitro even if an immotile spermatozoa from head of epiddymis is microinjected directly into an ovum.
  • Out of 120 million sperms formed each day by both testes, only a small quantity can be stored in epididymis but most are stored in vas deferensQ.
  • Progressive motality (i.e. ability to move forward) is acquired in epididymis by activation of Cat sper protein localized to principal piece of sperm tail. This protein is a Ca++ ion channel that permits cAMP generalized Ca’+ influx.
  • Ejaculation involves P2 x receptor ligand gated cation channels (that respond to ATP) mediated contraction of vas deferens
  • Normal motile, fertile sperms are capable of flagellated movement at 1- 4 mm/min velocity. Its activity is greatly enhanced in a neutral & slightly alkaline medium and with increasing temperature (which also increases metabolism rate & so decreases life span). Mildly acidic medium decreases activity & strongly acidic medium causes rapid death.
  • Although sperm can live for many weeks in male genital ducts, once ejaculated their maximum life is 1-2 days in female genetal tractQ. When frozen at temperatures below – 100°c, sperms can be preserved for years.
  • Seminal vesicle provide the bulk (60%) volume of semenQ that flushes the spermatozoa & prostatic secretion out of urethra. It is rich in fructose, vitamin C (citric acid), K-F, fibrinogen, prostaglandins and flavins (giving yellow color). Prostaglandins aid fertilization by

–  Making female cervical mucus more receptive to sperm movement

–   Causing backward reverse peristaltic contractions in uterus & fallopian tubes to move the ejaculated sperm towards the ovaries.

  • Prostatic fluid is rich in calcium, citrate ion, phosphate ion, a clotting enzyme and a profibrinolysin and it provides slightly alkaline medium by neutralizing the acidity of other seminal fluids & voginaQ. It is important to note that fluid of vas deferens is acidic d/ t presence of citric acid & metabolic end products of sperm and so are vaginal secretions (pH 3.5- 4). Sperms are not optimally motile until pH of surrounding fluid is 6- 6.5 Spermatozoa express olfactory receptors & ovaries produce odorant molecules (chemotaxis)
  • After ejaculation spermatozoa undergo two processes in female genital tract to acquire the capability of fertilization.

Q. 17

Spermatogenesis is maintained by which hormones (s)

 A

Testosterone

 B

FSH

 C

LH

 D

All

Q. 17

Spermatogenesis is maintained by which hormones (s)

 A

Testosterone

 B

FSH

 C

LH

 D

All

Ans. D

Explanation:

A, B, & C i.e. Testosterone, FSH, & LH


Q. 18

Antibodies against sperms may develop after:

 A

Trauma

 B

Infection

 C

Vasectomy

 D

Orchidectomy

Q. 18

Antibodies against sperms may develop after:

 A

Trauma

 B

Infection

 C

Vasectomy

 D

Orchidectomy

Ans. C

Explanation:

C i.e. Vasectomy

50% of men who have been vasectomized develop antibodies against spermatozoaQ. This holds significance, as because of these antibodies reversal of vasectomy may not restore fertility, even when the reversal is successful.


Q. 19

All are tests for sperm, EXCEPT

 A

Florence test

 B

Luminal test

 C

Barberio test

 D

Acid phosphatase test

Q. 19

All are tests for sperm, EXCEPT

 A

Florence test

 B

Luminal test

 C

Barberio test

 D

Acid phosphatase test

Ans. B

Explanation:

B i.e. Luminal test


Q. 20

Spermin is detected in semen by which test‑

 A

Barberio test

 B

Florence

 C

ELISA

 D

Agglutination inhibition

Q. 20

Spermin is detected in semen by which test‑

 A

Barberio test

 B

Florence

 C

ELISA

 D

Agglutination inhibition

Ans. A

Explanation:

A i.e. Barberio test


Q. 21

Oligospermia caused by-

 A

Methotrexate

 B

Hydroxychloroq uine

 C

Leflunomide

 D

D-penicillamine

Q. 21

Oligospermia caused by-

 A

Methotrexate

 B

Hydroxychloroq uine

 C

Leflunomide

 D

D-penicillamine

Ans. A

Explanation:

Ans. is ‘a’ i.e., Methotrexate

“Transient but reversible oligospermia has been reported in males receiving high dose methotrexate for cancer chemotherapy”.

Defective oogenesis or spermatogenesis “Occurs in methotrexate therapy”


Q. 22

Spermicide acts by

 A

Release of acrosomal enzymes

 B

Lysis of cell membrane

 C

Glucose uptake inhibition

 D

None

Q. 22

Spermicide acts by

 A

Release of acrosomal enzymes

 B

Lysis of cell membrane

 C

Glucose uptake inhibition

 D

None

Ans. D

Explanation:

Ans. is None 

Chemical methods

o Include spermicides (vaginal chemical contraceptives).

  • Example —> Nanoxynol – 9

o Spermicides are surface – active agents which attach themselves to spermatozoa and inhibit oxygen uptake and kill sperms.


Q. 23

Internal spermatic fascia is derived from:

 A

External oblique aponeurosis

 B

Internal oblique fascia

 C

Fascia transversalis

 D

All of the above

Q. 23

Internal spermatic fascia is derived from:

 A

External oblique aponeurosis

 B

Internal oblique fascia

 C

Fascia transversalis

 D

All of the above

Ans. C

Explanation:

Spermatic fascia

  • It is a bilayered fascia covering the testis; both layers are derived from abdominal muscle or fascia.
  • The more superficial of these two layers,

– The external spermatic fascia, lies deep to the skin and dartos fascia of the testes, superficial to the cremaster muscle, and is a continuation of the aponeurosis of the external oblique muscle.

– The deeper internal spermatic fascia is deep to the cremaster muscle, directly surrounds the spermatic cord and its contents, and is a continuation of the abdominal transversalis fascia.



Q. 24

NOT a constituent of spermatic cord:

September 2012

 A

Ducts deferens

 B

Testicular artery

 C

Ilio-inguinal nerve

 D

Genital branch of genitofemoral nerve

Q. 24

NOT a constituent of spermatic cord:

September 2012

 A

Ducts deferens

 B

Testicular artery

 C

Ilio-inguinal nerve

 D

Genital branch of genitofemoral nerve

Ans. C

Explanation:

Ans. C i.e. Ilio-inguinal nerve

Ilioinguinal nerve

  • It is a branch of the first lumbar nerve (L1).
  • It separates from the first lumbar nerve along with the larger iliohypogastric nerve.
  • It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, and passes obliquely across the quadratus lumborum and iliacus.
  • The ilioinguinal nerve then perforates the transversus abdominis near the anterior part of the iliac crest, and communicates with the iliohypogastric nerve between the transversus and the obliquus internus.
  • It then pierces the obliquus internus, distributing filaments to it, and then accompanies the spermatic cord through the superficial inguinal ring.



Q. 25

Asthenospermia means:       

September 2005

 A

Reduction in number of sperms

 B

Reduction in motility of sperms

 C

Absence of sperms

 D

Absence of semen

Q. 25

Asthenospermia means:       

September 2005

 A

Reduction in number of sperms

 B

Reduction in motility of sperms

 C

Absence of sperms

 D

Absence of semen

Ans. B

Explanation:

Ans. B: Reduction in motility of sperms

Asthenozoospermia/”asthenospermia” is the term for reduced sperm motility. It decreases the sperm quality and is therefore one of the major causes of infertility or reduced fertility in men


Q. 26

WHO guidelines for minimal sperm count is:

September 2007

 A

10 million/ ml

 B

20 million/ml

 C

50 million/ ml

 D

60 million/ ml

Q. 26

WHO guidelines for minimal sperm count is:

September 2007

 A

10 million/ ml

 B

20 million/ml

 C

50 million/ ml

 D

60 million/ ml

Ans. B

Explanation:

Ans. B: 20 million/ml

According to WHO guidelines, minimum sperm values of normal sperm are

  • Volume: 2 ml
  • Concentration:20 million/ ml
  • Motility: 50%
  • Normal morphology: 30%

Q. 27

In azoospermia, the diagnostic test which can distinguish between testicular failure and obstruction in the vas deferens is:           

September 2012

 A

Estimation of FSH level

 B

Estimation of testosterone level

 C

Karyotyping

 D

FNAC of testes

Q. 27

In azoospermia, the diagnostic test which can distinguish between testicular failure and obstruction in the vas deferens is:           

September 2012

 A

Estimation of FSH level

 B

Estimation of testosterone level

 C

Karyotyping

 D

FNAC of testes

Ans. A

Explanation:

A i.e. Estimation of FSH level


Q. 28

Homologous sperm in IVF is:       

AFMC 12

 A

Between donor and wife

 B

Between husband and wife

 C

Between husband and surrogate

 D

Between donor and surrogate

Q. 28

Homologous sperm in IVF is:       

AFMC 12

 A

Between donor and wife

 B

Between husband and wife

 C

Between husband and surrogate

 D

Between donor and surrogate

Ans. B

Explanation:

Ans. Between husband and wife


Q. 29

Motile spermatozoa found in wet mount of vaginal secretions are indicative of intercourse within the past:

Karnataka 09; LIP 09; MAHE 11

 A

6 h

 B

12 h

 C

24 h

 D

48 h

Q. 29

Motile spermatozoa found in wet mount of vaginal secretions are indicative of intercourse within the past:

Karnataka 09; LIP 09; MAHE 11

 A

6 h

 B

12 h

 C

24 h

 D

48 h

Ans. B

Explanation:

Ans. 12 h


Q. 30

Spermine is detected by:

TN 08

 A

Takayama test

 B

Barberio’s test

 C

Florence test

 D

Acid phosphatase test

Q. 30

Spermine is detected by:

TN 08

 A

Takayama test

 B

Barberio’s test

 C

Florence test

 D

Acid phosphatase test

Ans. B

Explanation:

Ans. Barberio’s test


Q. 31

Following changes are seen during capacitation of a sperms except ‑

 A

Increased permeability to calcium

 B

Decreased permeability to calcium

 C

Removal of cholesterol from acrosome

 D

Increased motility

Q. 31

Following changes are seen during capacitation of a sperms except ‑

 A

Increased permeability to calcium

 B

Decreased permeability to calcium

 C

Removal of cholesterol from acrosome

 D

Increased motility

Ans. B

Explanation:

Ans. is ‘b’ i.e., Decreased permeability to calcium

Capacitation of sperm (spermatozoa)

Spermatozoa leaving the testis (seminiferous ubules) are not fully mobile. They continue their maturation and acquire their mobility during their passage through epididymis. From epididymis they come to vas deference, distal end of which also receives the secretions of seminal vesicle, and continues as the ejeculatory duct. The ejeculatory duct joins the prostatic urethra.

Once ejeculated into the the female, vaginal secretions improve the motility and fertilizing ability of sperms. Further exposure to secretions of female genital tract (in uterus and/or fallopian tube) further improves the mobility and fertilizing ability of the sperms. The beneficial effects of stay in the female genital tract are collectively called capacitation, from the isthmus, capacitated sperms move rapidly to the ampullas, where fertilization takes place.

Following changes occur during capacitation :-

i)     Uterine and fallopian tube fluids wash away the various inhibitory factors that suppress sperm activity in male genital tract.

ii)     Removal of cholesterol vesicle from acrosome so that acrosomal membrane becomes weak and can release enzyme at the time of fertilization.

iii)   Increase membrane permeability to calcium ion.


Q. 32

Spermatogenesis takes place in ‑

 A

Epididymis

 B

Seminiferous tubule

 C

Ductus deferens

 D

Prostate

Q. 32

Spermatogenesis takes place in ‑

 A

Epididymis

 B

Seminiferous tubule

 C

Ductus deferens

 D

Prostate

Ans. B

Explanation:

Ans. is ‘b’ i.e., Seminiferous tubule

Spermatogenesis occurs in seminiferous tubules.

  • Spermatogenesis refers to the process of formation of spermatozoa (sperm) from primitive germ cells (spermatogonia).
  • Steps in spermatogenesis involve :‑

i) Spermatogonia (primitive germ cells) undergo mitosis to form primary spermatocytes. Both spermatogonia and primary spermatocytes have diploid chromosomes (46 chromosomes or diploid of 23 chromosomes).

ii) Primary spermatocytes undergo meiosis to form secondary spermatocytes. Secondary spermatocytes have haploid (23) chromosomes.

iii) Secondary spermatocytes undergo mitosis to form spermatids.

iv) Spermatids do not divide further but undergo morphological changes to form sperms (spermatozoa). This step of formation of spermatozoa from spermatids is called spermiogenesis. The spermiogenesis takes place in the deep folds of cytoplasm of sertoli cells.


Q. 33

Role of growth hormone in spermatogenesis ‑

 A

Late division of spermatocytes

 B

Early division of spermatogonia

 C

Formation of Acrosomes

 D

Stimulation of sertoli and Leydig cells

Q. 33

Role of growth hormone in spermatogenesis ‑

 A

Late division of spermatocytes

 B

Early division of spermatogonia

 C

Formation of Acrosomes

 D

Stimulation of sertoli and Leydig cells

Ans. B

Explanation:

Ans. is `b’ i.e., Early division of spermatogonia

Growth hormone specifically promotes early divisions of spermatogonia themselves. In the absence of GH, spermatogenesis is severely deficient or absent.

Growth hormone is also essential for general metabolic process in testis.

Hormones involved in spermatogenesis

 Spermatogenesis is influenced by many hormones. Hormones required for spermatogenesis are FSH, LH, testosterone, estrogen, growth hormones inhibin and activin.

FSH is responsible for initiation of spermatogenesis. It binds with sertoli cells and spermatogonia and induces the proliferation of spermatogonia. It stimulates certoli cells to secrete endrogen binding protein, inhibin, mullerian inhibing substance and estrogen.

LH stimulates leydig cells to secrete testosterone.

Testosterone is the principles hormone which directly stimulates spermatogenesis. It is responsible for the sequence of remaining stages of spermatogenesis (after initiatin by FSH). It is also responsible for maintenance of spermatogenesis.

Estrogen is formed from testosterone (by aromatase) in sertoli cells. It is essential for spermeogenesis (last step of spermatogenesis, i.e. formation of spermatozoa from spermatids).

Growth hormone is essentialy promotes early division of spermatogonia.

Inhibin plays an important role in regulation of spermatogenesis by feedback inhibition of FSH secretion.

Activin stimulates FSH secretion and stimulates spermatogenesis.


Q. 34

All of the following are involved in sperm pathway, except ‑

 A

Efferent tubule

 B

Afferent tubule

 C

Rete testes

 D

Epididymis

Q. 34

All of the following are involved in sperm pathway, except ‑

 A

Efferent tubule

 B

Afferent tubule

 C

Rete testes

 D

Epididymis

Ans. B

Explanation:

The correct sequence of sperm movement from within testis to urethra is

Seminiferous tubule  Straight tubule (Tubulirecti) → Rete testes → Efferent tubule → Epididymis → Vas (ductus) deferens Ejaculatory duct → Prostatic urethra

Testis consists of 200-300 lobules. Each lobules consists of 2-3 seminiferous tubules (where spermatozoa are formed). Seminiferous tubules join at the apex of lobules to form straight tubules, which anastomose with each other to form rete testis. Which emerge from upper pole and enter the epididymis. Each tubule becomes highly coiled to form a lobe of the head of epididymis. All tubules end in a single duct which is coiled on itself to form the body and tail of the epididymis. It is continuous with ductus deference.


Q. 35

Middle piece of sperm contains ‑

 A

Golgi apparatus

 B

Mitochondria

 C

Lysosome

 D

Ribosome

Q. 35

Middle piece of sperm contains ‑

 A

Golgi apparatus

 B

Mitochondria

 C

Lysosome

 D

Ribosome

Ans. B

Explanation:

Ans. is ‘b’ i.e., Mitochondria


Q. 36

Ion responsible to prevent polyspermy at the time of fertilization in mammals is –

 A

Na

 B

K

 C

Ca

 D

Mg

Q. 36

Ion responsible to prevent polyspermy at the time of fertilization in mammals is –

 A

Na

 B

K

 C

Ca

 D

Mg

Ans. C

Explanation:

Ans. is ‘c’ i.e., Ca

Only one sperm can enter into oocyte, and further entry of sperms is prevented by the activation of ovum.

  • Fusion of membranes of the gametes (sperm and ovum) leads to ovum activation which involves following events:-
  • Membrane potential of ovum decreases (depolarization).
  • Release of calcium ions from intracellular egg reserve leads to exocytosis of cortical granules into the perivitelline space.
  • The spread of cortical granules along perivitelline membrane prevents further entry of sperm into the ovum.
  • This is called vitelline block to polyspermy.

Q. 37

Acrosome cap of sperm is derived from ‑

 A

Golgi body

 B

Mitochondria

 C

Nucleus

 D

Centromere

Q. 37

Acrosome cap of sperm is derived from ‑

 A

Golgi body

 B

Mitochondria

 C

Nucleus

 D

Centromere

Ans. A

Explanation:

Ans. is ‘a’ i.e., Golgi body

Formation of acrosome starts with the coalescence of a series of granules from the Golgi complex, which migrates to come into contact with nuclear membrane, where it covers like a cap-like structure ove 30% to 50% of nuclear surface.

The acrosome covers the nucleus and contains the hydrolytic enzymes necessary for fertilization.

`The head also contains the acrosome, which is a cap-like structure represented by golgi complex and covers about two thirds of anterior head area’     Clinical reproductive medicine.


Q. 38

Development of spermatozoa (sperm) from spermatogonium takes how much time ‑

 A

30-35 days

 B

40-45 days

 C

50-55 day

 D

70-75 days

Q. 38

Development of spermatozoa (sperm) from spermatogonium takes how much time ‑

 A

30-35 days

 B

40-45 days

 C

50-55 day

 D

70-75 days

Ans. D

Explanation:

Ans. is ‘d’ i.e., 70-75 days

  • Spermatogenesis refers to the process of formation of spermatozoa (sperm) from primitive germ cells (spermatogonia).
  • Spermatogenesis begins at puberty and continues throughout adult life to decline in old age.
  • In humans, it takes an average of 74 days to form a mature sperm from primitive germ cells.
  • Spermatogenesis occurs in seminiferous tubules.

Q. 39

Acrosome cap of sperm derived from ‑

 A

Golgi body

 B

Mitochondria

 C

Nucleus

 D

Centromere

Q. 39

Acrosome cap of sperm derived from ‑

 A

Golgi body

 B

Mitochondria

 C

Nucleus

 D

Centromere

Ans. A

Explanation:

Ans. is ‘a’ i.e., Golgi body


Q. 40

Primary spermatocytes, chromosome is ‑

 A

23-X

 B

23-Y

 C

46-XY

 D

None

Q. 40

Primary spermatocytes, chromosome is ‑

 A

23-X

 B

23-Y

 C

46-XY

 D

None

Ans. C

Explanation:

Ans. is ‘c’ i.e., 46-XY


Q. 41

In early phase division of spermatogonia by‑

 A

Meiosis

 B

Mitosis

 C

Both Meiosis & Mitosis

 D

Maturation

Q. 41

In early phase division of spermatogonia by‑

 A

Meiosis

 B

Mitosis

 C

Both Meiosis & Mitosis

 D

Maturation

Ans. B

Explanation:

Ans. is ‘b’ i.e., Mitosis


Q. 42

Sperm acquires motility in ‑

 A

Seminal vesicle

 B

Testes

 C

Epididymis

 D

Ejaculatory duct

Q. 42

Sperm acquires motility in ‑

 A

Seminal vesicle

 B

Testes

 C

Epididymis

 D

Ejaculatory duct

Ans. C

Explanation:

Ans. is ‘c’ i.e., Epididymis

Spermatozoa leaving the testis (seminiferous ubules) are not fully mobile. They continue their maturation and acquire their mobility during their passage through epididymis. From epididymis they come to vas deference, distal end of which also receives the secretions of seminal vesicle, and continues as the ejeculatory duct. The ejeculatory duct joins the prostatic urethra.

Once ejeculated into the the female, vaginal secretions improve the motility and fertilizing ability of sperms. Further exposure to secretions of female genital tract (in uterus and/or fallopian tube) further improves the mobility and fertilizing ability of the sperms. The beneficial effects of stay in the female genital tract are collectively called capacitation, from the isthmus, capacitated sperms move rapidly to the ampullas, where fertilization takes place.


Q. 43

True about spermatid ‑

 A

Derived from primary spermatocyte

 B

Derived from secondary spermatocyte

 C

Undergoes mitotic division

 D

Undergoes meiotic division

Q. 43

True about spermatid ‑

 A

Derived from primary spermatocyte

 B

Derived from secondary spermatocyte

 C

Undergoes mitotic division

 D

Undergoes meiotic division

Ans. B

Explanation:

Ans. is ‘b’ i.e., Derived from secondary spermatocyte


Q. 44

After ejaculation into vagina sperm retains motility for ‑

 A

24hrs

 B

36hrs

 C

72 hrs

 D

1 week

Q. 44

After ejaculation into vagina sperm retains motility for ‑

 A

24hrs

 B

36hrs

 C

72 hrs

 D

1 week

Ans. A

Explanation:

Ans. is ‘a’ i.e., 24hrs

“In ejaculated semen the maximum life span of sperm is 24-48 hours at body temperature”.           — Indu Khurana


Q. 45

 Spermatic structure  (marked with B ) shown in the photograph is 

 A

 Head 

 B

 Neck 

 C

 Middle piece 

 D

. End piece

Q. 45

 Spermatic structure  (marked with B ) shown in the photograph is 

 A

 Head 

 B

 Neck 

 C

 Middle piece 

 D

. End piece

Ans. C

Explanation:

Middle piece (Description: Contains mitochondria)


Q. 46

Internal spermatic fascia is derived from ‑

 A

External oblique muscle

 B

Internal oblique muscle

 C

Fascia transversalis

 D

Colle’s fascia

Q. 46

Internal spermatic fascia is derived from ‑

 A

External oblique muscle

 B

Internal oblique muscle

 C

Fascia transversalis

 D

Colle’s fascia

Ans. C

Explanation:

Ans. is ‘c’ i.e., Fascia transversalis 

Layers of the scrotum

  • The scrotum is made up of the following layers from outside inwards.
  1. Skin, continuation of abdominal skin.
  2. Dartos muscle which replaces the superficial fascia. The dartos muscle is prolonged into a median vertical septum between the two halves of the scrotum.
  3. The external spermatic fascia from external oblique muscle.
  4. The cremasteric muscle and fascia from internal oblique muscle.
  5. The internal spermatic fascia from fascia transversalis


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