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Embryology MCQ

By AdminPosted On 05-Oct-2016

1. In fertilization : Embryology MCQ



a) The whole spermatozoon penetrates the ovum

b) The ovum reaches the uterus within 24 h

c) After penetration cortical granules appear around the perimeter of the egg

d) The second meiotic division is completed just before penetration by the spermatozoon

e) The first division of the ovum occurs 6 h after fertilization

Correct Answer: c and d. Cortical granules prevents further penetration by any other spermatozoa. Corrected False statements: a) Only head piece containing nucleus passes into the cytoplasm of the oocyte, leaving behind tail piece. b) Movement of ovum into the fallopian tube is temporarily halted into the ampula for upto 38 h, and allows additional time for fertilization. e) Within 30 h of fertilization, the first cell division occurs.


2. Mullerian Anomaly : Embryology MCQ


Complete failure of fusion of the mullerian duct leads to


a) Uterus didelphys

b) Arcuate uterus

c) Subseptate uterus

d) Unicornuate uterus

e) Uterus Bicornis unicollis

Correct Answer: a) Uterus didelphys. The uterus is formed by the union of the two mullerian ducts at about the 10th week. Any failure to fuse the two mullerian ducts or failure to resorb the cavity between them results in separate uterine horns or some degree of persistent uterine septum. Complete failure of fusion of the mullerian duct leads to Uterus didelphys (two separate uteri and cervices). Ref: Williams Obstetrics


3. Median Umbilical Ligament : Embryology MCQ


The median umbilical ligament is the embryological remnant of what fetal structure?


a) Gubenaculum

b) Umbilical arteries

c) Umbilical vein

d) Urachus

e) Vitelline duct


Correct Answer: d) Urachus forms the median umbilical ligament. Be careful not to confuse it with the medial umbilical ligament, which represents the remnants of fetal umbilical arteries. Note there is an umbilical vein, not veins, and this forms the ligamentum teres hepatis.


4. Ovary develop from : Embryology MCQ


a) Mullerian duct

b) Genital ridge

c) Genital tubercle

d) Mesonephric duct

e) Sinovaginal bulbs


Correct Answer: b) Genital ridge. Also called as gonadal ridge.


5. Oocyte : Embryology MCQ


How many oocytes are available at the time of puberty?


a) 100 000

b) 400 000

c) 800 000

d) 1 million

e) 2 million


Correct Answer: b) 400 000. There are 1-2 million primordial follicles present at birth but through the atretic process only 400 000 oocytes are available at puberty.


6. Gonads develop from which cell layer?


a) Endoderm

b) Intermediate mesoderm

c) Lateral mesoderm

d) Paraxial mesoderm

e) Surface ectoderm


Correct Answer: b) Intermediate mesoderm. The gonads and urogenital system develop from the intermediate mesoderm. Skeletal muscles, the skeleton, the dermis and connective tissue develop from paraxial mesoderm. The lateral plate mesoderm develops into the serous membrane of the body.


7. Second Meiotic Division : Embryology MCQ


In the development of the oocyte, when does the second meiotic division occur?


a) At birth

b) At fertilisation

c) At menarche

d) At ovulation

e) Before fertilisation


Correct Answer: b) At fertilisation. The primary oocyte resumes meiotic maturation in response to a surge in luteinising hormone. This results in a polar body and the secondary oocyte. The oocyte is then ovulated and enters the second meiotic cycle. It is arrested in metaphase II and only completes meiosis after the entry of the spermatozoa at fertilisation.


8. Sperm Cell : Embryology MCQ


Which sperm cell type undergoes the second meiotic division?


a) Primary spermatocytes

b) Secondary spermatocytes

c) Sperm

d) Spermatids

e) Spermatogonium


Correct Answer: b) Secondary spermatocytes. Spermatogoniun are diploid and divide by mitosis to produce diploid primary spermatocytes. These divide by the first stage of meiosis to create haploid secondary spermatocytes. Secondary spermatocytes complete the second stage of meiosis to become spermatids. The conversion from spermatids to sperm is known as spermiogenesis.


9. Fertilisation : Embryology MCQ


In the process of fertilisation, what is the correct sequence for sperm penetration into the oocyte?


a) Corona radiata, zona pellucida, perivitelline space, plasma membrane

b) Corona radiata, zona pellucida, plasma membrane, perivitelline space

c) Zona pellucida, corona radiata, plasma membrane, perivitelline space

d) Zona pellucida, perivitelline space, corona radiata, perivitelline space

e) Zona pellucida, perivitelline space, plasma membrane, corona radiata


Correct Answer: a) Corona radiata, zona pellucida, perivitelline space, plasma membrane. The corona radiata is made up of the remnants of the cumulus cells. Once the sperm penetrates the corona radiata, the sperm binds to the zona pellucida and releases acromsomal enzymes, which are needed for penetration. The sperm then moves through the perivitelline space and comes into contact with the plasma membrane of the oocyte, resulting in the fusion of the membranes of the sperm head and oocyte.


10. Alveoli : Embryology MCQ


At what gestational age does the formation of the definitive alveoli take place?


a) 28 weeks

b) 30 weeks

c) 32 weeks

d) 34 weeks

e) 36 weeks


Correct Answer: e) 36 weeks. The alveolar stage starts at 36 week and may take up to 2 years postnatal to complete.


11. Gartner's Cyst : Embryology MCQ


A cystic structure is noted lateral to the vagina. This is believed to be a Gartners duct. What is the embryological origin of this structure?


a) Cloaca

b) Genital tubercle

c) Mesonephric duct

d) Paramesonephic duct

e) Urogenital septum


Correct Answer: c) Mesonephric duct. The mesonephric duct forms the ureter and collecting system and in the female can form the epoophoron, appendix vesiculosa and Gartner's duct.


12. Anal Canal : Embryology MCQ


The inferior one-third of the anal canal originates from which structure?


a) Cloacal membrane

b) Ectoderm of the proctodeum

c) Endoderm of the hind gut

d) Endoderm of the mid gut

e) Urorectal septum


Correct Answer: b) Ectoderm of the proctodeum. The junction between the superior and inferior part is delineated by a pectinate line, just below the anal columns. The endoderm of the hind gut develops into the superior part of the anal canal.


13. Implantation : Embryology MCQ


Implantation of the embryo occurs at which stage?


a) Blastocyst

b) Morula

c) Pronuclear phase

d) Trophoblast

e) Zygote


Correct Answer: a) Blastocyst. Within 24 hours of fertilisation, the zygote undergoes cleavage. It then further subdivides into blastomeres. By the third day, the embryo contains 12 cells. By the fourth day, it is comprised of 16-32 cells and is called a morula. On day 5, the blastocyst hatches from the zona pellucida and implants into the endometrium. For in vitro fertilisation, transfer of the embryo with blastocyst has been shown to be more effective and is recommended with a single embryo transfer.


14. Three Germ Layers : Embryology MCQ


Which of the following structure is derived from all three germ layers?


a) Hymen

b) Anus

c) Lips

d) Tympanic membrane

e) Uterus


Correct Answer: d) Tympanic membrane.

Uterus develops from intermediate mesoderm.

Tympanic membrane forms by the joining of expanding 1st pharyngeal pouch(endoderm lined) and groove (ectoderm lined) which is separated by a thin layer of splanchnic mesoderm. Hence, the 3 layers are derived from the 3 germinal layers.

1. Outer epithelial layer: Ectoderm

2. Middle fibrous layer: Mesoderm

3. Inner mucosal layer: Endoderm

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