Embryology Extra Questions

1. You are counseling a couple about infertility. In your discussion about conception, tubal disease, and implantation, you explain to them that implantation in the uterus occurs at which stage of development?

A. Eight-cell embryo
B. Zygote
C. Morula formation
D. Blastocyst
E. Embryonic disk

2. A 25-year-old G2 P1 had a previous child with ambiguous external genitalia including hypertrophied clitoris and labial fusion. She and her partner are carriers of 21-alpha hydroxylase deficiency.
In this pregnancy you counsel her that her fetus has what chance of recurrence?

A. 50% chance of recurrence
B. 25% chance of recurrence
C. <5% chance of recurrence
D. 100% chance of recurrence
E. Impossible to predict recurrence because of incomplete penetrance

3. A 25-year-old G2 P1 had a previous child with ambiguous external genitalia including hypertrophied clitoris and labial fusion. She and her partner are carriers of 21-alpha hydroxylase deficiency.
She would like to prevent a recurrence. You offer her maternal dexamethasone in order to do which of the following?

A. Calm her anxiety
B. Suppress fetal adrenal glad
C. Block fetal genital steroid receptors
D. Provide negative feedback to the maternal pituitary
E. Block transplacental passage of maternal androgens

4. In counseling a woman about an alcohol binge she had at 6 weeks after her last menstrual period you explain that, with the exception of the brain, organogenesis is completed within how many weeks after her last period?

A. 4 weeks after ovulation
B. 10 weeks after ovulation
C. 18 weeks after ovulation
D. 26 weeks after ovulation
E. 38 weeks after ovulation

5. A couple of Southeast Asian ancestry are both thalassemia carriers. In counseling them you explain that the main form of hemoglobin in the normal fetus is which of the following?

A. Gower 1
B. Hemoglobin A (HbA)
C. Gower 2
D. Hemoglobin F (HbF)
E. Bart’s hemoglobin

6. A woman has had a previous child with renal agenesis. She is a middle school biology teacher and wants to understand more about development of the kidneys. Which of the following best describes the function of pronephros?

A. They begin the developmental sequence that forms the permanent excretory ducts and kidneys.
B. They are the primitive kidney and ureter that will mature into the adult urinary tract.
C. They develop as the primitive kidney and migrate caudally and laterally to form the mesonephros.
D. They will serve as the fetal kidney until 16 weeks and the development of the metanephros.
E. They form the primitive kidney and primitive upper genital ducts.

7. An amniocentesis results show a fetus with 45XO. In counseling the parents, how would you explain that the genetic sex is determined?

A. At ovulation
B. At conception
C. By the presence or absence of testosterone
D. In the absence of Müllerian-inhibiting factor
E. Psychosocially after birth

8. A women is worried because she has been taking “body-building steroids” through week 10 of her pregnancy. One of the steroids has a strong proportion of androgens. You explain that androgens can cause which of the following?

A. Paramesonephros to differentiate into the proximal urinary duct system
B. Wolffian ducts to develop
C. Müllerian ducts to regress
D. The primitive vaginal tube to regress
E. The gonadal ridge to differentiate into a testis

9. Germ cells arise in which of the following?

A. Germinal epithelium of the gonad
B. Endoderm of the primitive gut
C. Müllerian duct
D. Mesonephros
E. Ovarian cortex

10. You are counseling a 32-year-old nulligravida with breast cancer about preserving fertility. You explain that the maximal number of oogonia is found at what age?

A. 1 month’s gestational age
B. 5 month’s gestational age
C. Birth
D. Puberty
E. 21 years of age

11. The paramesonephric ducts will form which of the following?

A. The prostatic utricle
B. Seminal vesicles
C. Oviducts, uterus, and upper vagina
D. Upper vagina only
E. The ureters

12. Vaginal epithelium and the fibromuscular wall of the vagina originate from which of the following, respectively?

A. Mesonephric duct and endoderm of the urogenital sinus
B. Mesonephric duct and the uterovaginal primordium
C. Endoderm of the urogenital sinus and the mesonephric duct
D. Endoderm of the urogenital sinus and the uterovaginal primordium
E. Endoderm of the urogenital sinus and the paramesonephric ducts

13. The urogenital sinus is derived from which of the following?

A. Invagination of the genital ridges
B. Proliferation of the hindgut
C. Partitioning of the endodermal cloaca
D. A track developing in the genital mesoderm
E. Hyperplasia of the metanephros

14. The labia majora are homologous to which male body part?

A. Penis
B. Testicle
C. foreskin
D. Scrotum
E. Gubernaculum testes

15. The female clitoris is homologous to which of the following male body parts?

A. Scrotum
B. Frenulum
C. Prostate
D. Foreskin
E. Penis

16. The absence of the vagina is common in which of the following?

A. Congenital adrenal hyperplasia in a female infant
B. Turner’s syndrome
C. Association with an absent or rudimentary uterus
D. Medication-induced fetal masculinization of a female infant
E. Gonadal dysgenesis

17. The fusion of the Wolffian duct system gives rise to the uterus, cervix, and upper vagina. Incomplete fusion may lead to several uterine anomalies from complete separation with two cervices— uterine didelphys to a mild form of incomplete fusion—uterine septae. Unilateral renal agenesis is associated with metanephros failure. Transverse septum and imperforate hymens are due to lack of dissolution of the cell cord of the fused Mullerian ducts and the urogenital sinus.

A. Uterine didelphys
B. Transverse vaginal septum
C. Unilateral renal agenesis
D. Imperforate hymen
E. Ovarian remnant syndrome

18. During early embryonic development the germ cells must migrate. If germ cells fail to enter the developing genital ridge, which of the following is most likely to occur?

A. Ovarian teratomas
B. Ectopic pregnancy
C. Ovarian choriocarcinoma
D. Gonadal agenesis
E. Testicular feminization

19. You are giving a lecture to a college physiology class. They are fascinated with the genetics and development of hermaphrodites. You explain that true hermaphrodites have which of the following?

A. Ovaries and testicular remnants
B. The absence of any Müllerian tissue due to Müllerian-inhibiting factor (MIF)
C. 46, XY karyotype
D. Ambiguous genitalia
E. External genitalia that are responsive to both adrenal and testicular androgens

20. In the examination of the newborn infant with ambiguous genitalia, which of the following is true?

A. Gonads that are palpable in the lower inguinal canal are always testes
B. The presence of descended gonads rules out high testosterone virilization in an otherwise normal female infant
C. Pelvic ultrasound is usually not helpful as a method of assessing a newborn with ambiguous genitalia
D. The presence of a normal uterus rules out the possibility of dysgenetic testes
E. If the urethra is superior to the phallus, the infant is a male

21. On ultrasound, a large isolated cyst is seen in the fetal pelvis. At birth a cloaca is seen in a female fetus. You explain to the parents that urorectal septum did not form thus resulting in which of the following?

A. The single-chambered cloaca did not divide into the urogenital sinus and anorectal canal.
B. The junction of the cloacal membrane and urorectal septum become the labia.
C. The cloacal membrane differentiated into the urogenital membrane and the anal membrane.
D. The urogenital sinus did not form the vagina and the lower bladder wall to the ureterovesical junction.
E. The urorectal septum did not form a rectum and lower third of the sigmoid colon.

22. Of the following anomalies, which is (are) most likely to proceed to a term pregnancy?

A. Uterus didelphys
B. Bicornuate uterus with a rudimentary horn
C. Unicornuate uterus
D. Longitudinal vaginal septum
E. Gartner’s duct cysts

23. With regards to spermatogenesis which of the following is correct?

A. 4 spermatozoa are produced from one primary spermatocyte.
B. The process occurs continuously from birth.
C. A spermatozoon is produced in 30 days.
D. Spermatogonia line the basal lamina of the epididymis.
E. Every spermatogonium develops into a primary spermatocyte.

24. Which of the following is correct with regards to spermiogenesis.

A. Nuclear material forms the acrosomal cap.
B. Mitochondria form a sheath for the neck of the spermatozoon.
C. The axial filament derives from the centriole.
D. In the endpiece of the tail there are 1central & 9 peripheral elements.
E. Spermatozoa may remain linked at cytoplasmic bridges.

25. Which of the following is correct with respect to oogenesis?

A. The early development of the primitive germ cells in the ovary during intrauterine life is meiosis.
B. Primary oocytes are formed after 37 weeks of gestation.
C. Some primary oocytes will remain in prophase for 12-50 years
D. Division of the secondary oocyte occurs at the time of ovulation.
E. At birth there are 7-8 million oocytes present.

26. During fertilisation which of the following events is true?

A. The whole spermatozoon penetrates the ovum.
B. The ovum reaches the uterus within 24 hours
C. After penetration cortical granules appear around the perimeter of the egg.
D. The second meiotic division is completed just before penetration by the spermatozoa.
E. The first division of the ovum occurs 6 hrs after fertilisation.

27. Which of the following in incorrect in early development & implantation

A. The zygote contains blastomeres
B. The morula is contained within the blastocyst
C. The embryo forms from trophoblast
D. The blastocyst implants about 10 days after fertilisation
E. Syncytiotrophoblast arises from the inner cell mass

28. During embryogenesis ,which of the following is incorrect?

A. The endocervical vesicle becomes the yolk sac.
B. The cells adjacent to the amniotic sac form endoderm
C. Ectodermal cells are tall, columnar cells
D. 3 layers of cells lie between the amniotic & yolk sacs.
E. Mesodermal cells develop principally from ectodermal division

29. In organogenesis which of the following statement is correct?

A. The neural tube develops on the ventral surface of the embryo.
B. The vitellointestinal duct may persist as Meckels diverticulum.
C. Paraxial mesoderm deivides into splanchnopleure & somatopleure
D. Limb buds develop from splanchnopleure
E. The buccopharyngeal membrane of the stomatodeum breaks down at the 6th week of life.

30. In development of the pharyngeal region which of the following holds true?

A. The upper & lower jaws develop from the first arch.
B. The styloid process develops from the 2nd arch.
C. The inferior parathyroids develop from the 3rd pouch.
D. The superior parathyroids develop from the 3rd pouch.
E. The arch of aorta develops from from the 4th arch artery

31. With regards to pharyngeal region,which of the following is incorrect?

A. The muscles of the tongue are developed from the 1st & 3rd arches.
B. The thyroid gland develops from the distal end of the thyroglossal duct.
C. A branchial cyst arises following failure of occlusion of the 2nd pharyngeal pouch.
D. The 5th pharyngeal arch is rudimentary & disappears.
E. The 4th & 6th arches contribute to the bones of the larynx.

32. Regarding development of the cardiovascular system,which of the following is incorrect?

A. The heart develops from the angiogenic cells.
B. The cardinal veins run into the sinus venosus.
C. The vitelline veins run into the right horn of sinus venosum.
D. A beating fetal heart tube can be recognised by ultrasound techniques from 32nd day of intrauterine life.
E. In the foramen ovale blood passes from left to right.

33. With respect to the cardiovascular system which of the following is correct?

A. The proximal bulbar septum divides the aorta from the pulmonary artery.
B. Deoxgenated blood passes via the umbilical vein to the left branch of the portal vein.
C. The ligamentum venosum is the obliterated umbilical vein.
D. There is a single umbilical artery.
E. The foramen ovale usually closes 1 month after birth.

34. In development of the alimentary system which of the following is correct?

A. The foregut ends at the pyloric sphincter.
B. The spleen is a derivative of the foregut.
C. The pancreas is a derivative of the midgut.
D. The stomach forms a sac at the 5th week of intrauterine life.
E. The hindgut opens into the vitellointestinal duct.

35. Which of the following is incorrect with regards to development of diaphragm?

A. Develops from septum transversum.
B. Develops from pleuroperitoneal membrane
C. Develops from the costal margin.
D. Develops from the gastrohepatic ligament.
E. Has a small contribution from the endoderm around the aorta.

36. Which of the following is incorrect with regards to development of the nervous system?

A. The cerebral hemispheres originate from the cerebral vesicles.
B. The lateral ventricles develop from the side wall of the foremost part of the neural tube.
C. The neural crest cells give rise to the adrenal medulla.
D. The commonest form of spina bifida is cervicothoracic.
E. The notochord is ectodermal.

37. Which of the following is correct with regards to development of the skeletal system?

A. There are 3 ossification centres in each vertebra.
B. The nucleus pulposus is derived from a cartilaginous ring.
C. The vault of the skull is preformed in cartilage.
D. Limb buds appear at the 7th week of intrauterine life.
E. Synovial joints arise from endoderm

38. Which of the following is correct with regards to development of the muscles & skin?

A. The muscles of the head & neck develop from mesenchyme of the pharyngeal arches.
B. The skin plate arises from proliferation of spindle cells of the dermomyotome.
C. The involuntary muscles of the bladder arise from the dorsal part of the muscle plate.
D. Sweat glands arise from the skin plate.
E. Sebaceous glands are endodermal structures.

39. Which of the following is incorrect ,in development of the genital organs?

A. The pronephros arises in intermediate mesoderm
B. The pronephros is found in the trunk.
C. The mesonephros appears in the thoracic & lumbar region.
D. The wolffian duct connects with the tubules of the mesonephros.
E. The genital ridge appears on the lateral aspect of the mesonephros.

40. During development of uterus,tubes & vagina which of the following is correct?

A. The paramesonephric ducts reach the urogenital sinus by week 7.
B. At 9 weeks both mesonephric & paramesonephric ducts are present.
C. Muscular walls develop in the uterus in the 6th month.
D. The vaginal plate is composed of urogenital sinus epithelium & mesonephric ducts.
E. The vagina is a solid organ until 30 weeks.

41. Which of the following is correct with regards to development of the external genitalia?

A. The genital swellings are medial to the genital folds.
B. The genital tubercle becomes the clitoris in females.
C. The phallic part of the urogenital sinus reaches cranially to the point where the Mullerian ducts enter the sinus wall.
D.The vestibule is derived from both the pelvic & phallic portions of the urogenital sinus.
E. Ectopia vesicae results from deficient development of the genital folds.

42. Which of the following is correct with respect to the developing testes?

A. Primitive germ cells arise from beneath the epithelium of the amniotic sac.
B. Gonadal differentiation can be seen at 5 weeks
C. Sex cords develop from coelomic epithelium
D. The interstitial cells of Leydig arise from coelomic epithelium
E. The rete testis arises from the underlying mesoderm

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