Pre Clinical Medical Science SBAs
Pre Clin Reproduction: (57 questions)

Questions

• 1
  What is the appendix testis (hydatid of Morgangi)?
  Difficulty: Easy     Topic: Appendix testis
  a

  Part of epididymus

  b

  Part of tunica vaginalis

  c

  Remnant of gubernaculum

  d

  Remnant of mesonephric duct

  e

  Remnant of paramesonephric ducts
  Explanation: The appendix testis (or hydatid of Morgangi) is a small piece of tissue on the superior pole of the testicle that is a remnant of the Mullerian (paramesonephric) ducts. It can undergo torsion, which mimics testicular torsion.
• 2
  What is the term given to a placenta that is located abnormally close to the cervix?
  Difficulty: Hard     Topic: Placental abnormalities
  a

  Placenta accreta

  b

  Placenta hydatid mole

  c

  Placenta increta

  d

  Placenta percreta

  e

  Placenta praevia
  Explanation: Placenta praevia is a one that has implanted in the lower segment of the uterus and poses a risk to obstructing the birth canal. Placenta accreta, increta ad percreta are variations of a placenta that is too deeply attached into the uterus. A hydatid mole is a pre-malignant placental tumour with irregular structure and abnormal genetics.
• 3
  Which foetal hormone is the first to rise in stimulating parturition?
  Difficulty: Easy     Topic: Parturition
  a

  Cortisol

  b

  Oestrogen

  c

  Oxytocin

  d

  Progesterone

  e

  Prolactin
  Explanation: Pregnancy is characterised by much higher levels of progesterone than oestrogen. Towards the end of gestation, foetal cortisol rises, which causes a maternal hormones to switch towards increased oestrogen and a fall in progesterone. This causes changes in the myometrium that promote labour.
• 4
  What is the Ferguson reflex?
  Difficulty: Medium     Topic: Ferguson reflex
  a

  Progesterone inhibits release of oxytocin

  b

  Prostaglandins stimulating release of oxytocin

  c

  Suckling stimulates prolactin release

  d

  Vaginal distension causes increases progesterone synthesis

  e

  Vaginal distension causes positive feedback for oxytocin release
  Explanation: The Ferguson reflex is an example of a positive feedback reflex that takes place during labour. Oxytocin (from the posterior pituitary) stimulates myometrial contraction. Movement of the foetus into the vaginal canal causes vaginal distension and mechanoreceptors in the uterus detect increased force - these signal to the hypothalamus to increase oxytocin release.
• 5
  In what orientation does the foetal head normally engage with the pelvis?
  Difficulty: Medium     Topic: Parturition 1
  a

  Face anteriorly

  b

  Face laterally

  c

  Occiput anteriorly

  d

  Occiput laterally

  e

  Occiput posteriorly
  Explanation: Engagement is the process of the widest part of the foetus' skull passing into the true pelvis. The pelvic inlet is widest laterally whereas the pelvic outlet is widest in the antero-posterior direction. Therefore the foetus engages with the occiput laterally, which requires the neck to be flexed. If the neck is extended then the face may engage, which increases risk of injury to mother and foetus - this is relatively rare.
• 6
  In childbirth, what is meant by restitution?
  Difficulty: Easy     Topic: Parturition 2
  a

  Contraction of the myometrium to prevent blood loss

  b

  External rotation of the head to come in-line with the shoulders

  c

  External rotation of the head to the A-P position

  d

  Internal rotation of the shoulders to come in-line with the head

  e

  Internal rotation of the shoulders to the A-P position
  Explanation: Restitution is one of the final movements in childbirth. The head passes through the pelvic outlet with the occiput in the A-P orientation and at this stage the shoulders rotate to also become positioned A-P in preparation for pass through the outlet. The head rotates externally (to face the thigh) to come in-line with shoulders, which is known as restitution.
• 7
  What is the function of the ductus arteriosus?
  Difficulty: Easy     Topic: Ductus arteriosus 1
  a

  Transmit deoxygenated blood from aorta to pulmonary artery

  b

  Transmit deoxygenated blood from pulmonary vein to pulmonary artery

  c

  Transmit oxygenated blood from aorta to pulmonary artery

  d

  Transmit oxygenated blood from aorta to pulmonary veins

  e

  Transmit oxygenated blood from pulmonary artery to aorta
  Explanation: The ductus is a muscular vessel connecting the pulmonary artery and the aortic arch in the foetus. It functions to reduce passage of oxygenated blood through the lungs by passing blood from the pulmonary artery to the aorta. Pulmonary vascular resistance is high in the foetus (as the lungs are fill of amniotic fluid) so pressures are higher than in the systemic circulation, which permits this direction of flow.
• 8
  What key change cardiorespiratory change in the 3rd trimester is stimulated by a rise in foetal cortisol?
  Difficulty: Medium     Topic: Changes at 3rd trimester
  a

  Closure of ductus arteriosus

  b

  Fall in pulmonary artery pressure

  c

  Rise in arterial oxygen tension

  d

  Rise in cardiac output

  e

  Surfactant production
  Explanation: Type 2 pneumocytes in foetal lungs start to secrete surfactant in response to a rise in foetal cortisol levels late in the 3rd trimester; this is vital to facilitate breathing at birth. Entry of air into the lungs causes a fall in pulmonary artery pressures, the rise in oxygen tension, ductus closure and the rise in cardiac output - surfactant facilitates this.
• 9
  What change causes closure of the ductus arteriosus at birth?
  Difficulty: Medium     Topic: Ductus arteriosus 2
  a

  Fall in oestrogen

  b

  Fall in prostaglandins

  c

  Rise in oestrogen

  d

  Rise in progesterone

  e

  Rise in prostaglandins
  Explanation: The ductus arteriosus remains patent during gestation but normally closes within 24-hours of birth in response to a fall in prostaglandins, which is secondary to raised oxygen tension. Prostaglandins maintain the vessel's patency by vasodilatation however in the presence of oxygen prostaglandin levels fall. Use of NSAIDs can promote closure of the ductus arteriosus.
• 10
  Which of the following abnormalities is NOT classically part of the tetralogy of Fallot?
  Difficulty: Hard     Topic: Tetralogy of Fallot
  a

  Over-riding aorta

  b

  Patent ductus arteriosus

  c

  Pulmonary stenosis

  d

  Right ventricular hypertrophy

  e

  Ventricular septal defect
  Explanation: Tetralogy of Fallot is 4 abnormalities that occur together at a higher rate than would be expected spontaneously. The aorta sits over a ventricular septal defect, therefore receives mixed oxygenated and deoxygenated blood, causing cyanosis. In addition, stenosis of the pulmonary outflow tract causes right ventricular hypertrophy. PDA is not part of the tetralogy.
• 11
  What structure leads descent of the testes from the posterior abdominal wall?
  Difficulty: Medium     Topic: Testicular descent
  a

  Cremaster muscle

  b

  Ductus deferens

  c

  Gubernaculum

  d

  Processus vaginalis

  e

  Tunica albuginea
  Explanation: The gubernaculum is an embryological structure that is attached to the gonads on the posterior abdominal wall and guides their descent through the abdominal cavity, inguinal canal and layers of the abdominal wall into the scrotum. The processus vaginalis is an extension of the peritoneal cavity that also moves through the inguinal canal at the same time.
• 12
  From deep to superficial, what are the first three tissues covering the testes?
  Difficulty: Easy     Topic: Testicular coverings
  a

  Internal spermatic fascia, external spermatic fascia, cremastic muscle

  b

  Tunica albuginea, cremasteric muscle, tunica vaginalis

  c

  Tunica albuginea, tunica vaginalis, internal spermatic fascia

  d

  Tunica vaginalis, cremastic muscle, tunica albuginea

  e

  Tunica vaginalis, internal spermatic fascia, cremasteric muscle
  Explanation: The tests is covered by several tissues, from deep to superficial: tunica albuginea, tunica vaginalis (visceral then parietal), internal spermatic fascia, cremasteric muscle, external spermatic fascia, Colles' fascia, Dartos muscle and then skin. These are all derived from the layers of the abdominal wall.
• 13
  Which muscle causes a unilateral elevation of the testis on stroking of the inner thigh?
  Difficulty: Medium     Topic: Penile muscles
  a

  Bulbospongiosus

  b

  Cremasteric muscle

  c

  Dartos muscle

  d

  Ischiocavernosus

  e

  Levator ani
  Explanation: The cremasteric reflex is unilateral testicular elevation following stimulation of the inner thigh due to cremasteric muscle. It is dervied from internal oblique and transversus abdominus. Bulbospongiosus and ischiocavernosus are involved in erection. Dartos muscle wrinkles the scrotal skin. Levator ani forms part of the pelvic floor.
• 14
  What is the role of the rete testis?
  Difficulty: Easy     Topic: Rete testis
  a

  Attach testis to the inferior of the scrotum

  b

  Attach testis to the posterior of the scrotum

  c

  Drain into seminiferous tubules

  d

  Drain the epididymus from one testis

  e

  Drain the seminiferous tubules from one testis
  Explanation: The rete testis is the area on the postero-superior aspect of the testis that drains all the seminiferous tubules; it then drains into the epididymus. The gubernaculum attaches the testis to the inferior scrotum; the epididymus attaches to the posterior wall.
• 15
  How is venous blood drained from the left testis?
  Difficulty: Easy     Topic: Testicular drainage
  a

  Gonadal vein drains into the IVC

  b

  Gonadal vein drains into the left renal vein

  c

  Via the pampiniform plexus into the external iliac vein

  d

  Via the pampiniform plexus into the internal iliac vein

  e

  Via the pampiniform plexus into the sacral venous plexus
  Explanation: The gonadal (testicular) blood supply originates from the level of L1 on the posterior abdominal wall. The right vein drains directly into the IVC whereas the left vein drains into the left renal vein. Both testicles have a pampiniform plexus that lead into their gonadal veins.
• 16
  What is the underlying pathology in pre-eclampsia?
  Difficulty: Hard     Topic: Pre-eclampsia
  a

  Bleeding from between the placenta and decidua

  b

  Inefficient foetal-maternal oxygen exchange

  c

  Insufficient macronutrient supply to the foetus

  d

  Insufficient spiral artery remodelling

  e

  Malignant transformation of the placenta
  Explanation: Pre-eclampsia is a systemic condition caused by failure of invasion of the extravillous trophoblastic, with consequent insufficient remodelling of the maternal spiral arteries. The high-resistance vessels causes systemic endothelial hyperactivation with potential to cause multiple organ failure.
• 17
  The ejaculatory duct is formed from the union of which two structures?
  Difficulty: Easy     Topic: Ejaculatory duct
  a

  Bulbo-urethral glands and seminal vesicles

  b

  Seminal vesicles and ductus deferens

  c

  Urethra and bulbo-urethral glands

  d

  Urethra and ductus deferens

  e

  Urethra and seminal vesicles
  Explanation: The ductus deferens passes posterior to the bladder and is joined by the ducts from the seminal vesicles within the prostate, called the ejaculatory duct. This meets the descending urethra also within the prostate. The bulbo-urethral glands are at the base of the penis and drain into the urethra.
• 18
  What is the covering of the corpora cavernosa?
  Difficulty: Easy     Topic: Penile tissues
  a

  Corpus spongiosum

  b

  Cremasteric fascia

  c

  Ischiocavernosus

  d

  Tunica albuginea

  e

  Tunica vaginalis
  Explanation: The corpora cavernosa are two highly vascular structures that run the length of the penis. They are bound by the fibrous tunica albuginea, which also encircles the corpus spongiosum, which transmits the urethra. The cremasteric fascia is in the scrotum and spermatic cord. Ischiocavernosus is a muscle that attaches to the corpora cavernosa and the ischial tuberosities.
• 19
  How is an erection generated?
  Difficulty: Easy     Topic: Erection
  a

  Parasympathetic vasodilatation and physical venous compression

  b

  Parasympathetic venoconstriction alone

  c

  Physical arterial compression and sympathetic venoconstriction

  d

  Sympathetic vasodilatation and physical venous compression

  e

  Sympathetic venodilatation alone
  Explanation: Parasympathetic mediated vasodilatation causes increased blood flow through the internal pudendal artery, which results in swelling of the blood channels in the corpora cavernosa. They expand but are limited by the tunica albuginea, which exerts physical compression on penile veins to reduce venous outflow.
• 20
  What forms the medial floor of the inguinal canal?
  Difficulty: Easy     Topic: Inguinal canal boundaries 1
  a

  Conjoint tendon

  b

  Inguinal ligament

  c

  Lacunar ligament

  d

  Pubic bone

  e

  Transversalis fascia
  Explanation: The floor of the inguinal canal is made of the inguinal ligament (running from the pubic tubercle to the anterior superior iliac spine) for the lateral 2/3rd. The medial 1/3rd is called the lacunar ligament and it is formed from the a continuation of the inguinal ligament plus the insertion of the conjoint tendon.
• 21
  What structure(s) form(s) the posterior wall of the medial inguinal canal?
  Difficulty: Easy     Topic: Inguinal canal boundaries 2
  a

  Conjoint tendon alone

  b

  Conjoint tendon and transversalis fascia

  c

  External and internal oblique

  d

  Internal oblique and transversalis fascia

  e

  Transversalis fascia alone
  Explanation: The posterior wall of the inguinal canal is formed by transversalis fascia only laterally but laterally but medially the conjoint tendon has looped over the canal and joins the posterior wall. The conjoint tendon is the fused insertion of internal oblique and transversus abdominus.
• 22
  What are the borders of Hesslebach’s triangle?
  Difficulty: Hard     Topic: Hesslebach's triangle
  a

  Linea alba, inferior epigastric vessels, inguinal ligament

  b

  Linea alba, superior epigastric vessels, inguinal ligament

  c

  Linea semiluminares, inferior epigastric vessels, inguinal ligament

  d

  Linea semiluminares, superior epigastric vessels, arcuate line

  e

  Linea semiluminares, superior epigastric vessels, inguinal ligament
  Explanation: Hesslebach's triangle describes the area through which direct inguinal hernias occur. It is bound medially by the linea semiluminares (the lateral border of rectus abdominus), superolaterally by the inferior epigastric vessels (that traverse the inguinal canal) and the inguinal (and lacunar) ligament inferiorly.
• 23
  Which ligament carries the ovarian artery from the lateral wall of of the abdomen?
  Difficulty: Easy     Topic: Ovarian artery
  a

  Broad ligament

  b

  Ligamentum flavum

  c

  Round ligament

  d

  Suspensory ligament of ovary

  e

  Utero-ovarian ligament
  Explanation: The ovarian arteries branch from the aorta at L1 and pass inferiorly along the posterolateral abdominal wall. At the level of the pelvic brim they turn towards the ovaries and run inside the suspensory ligament of the ovary. The broad ligament covers the uterus and Fallopian tubes. The ligamentum flavum is within the spinal column. The round ligament passes from the uterus, through the inguinal canal to the labia minora. The utero-ovarian ligament is short and passes between the two structures.
• 24
  At what level does the muscular pelvic diaphragm support the female reproductive organs?
  Difficulty: Easy     Topic: Pelvic diaphragm
  a

  Uterine fundus

  b

  Cervix

  c

  Upper 1/3 vagina

  d

  Lower 2/3 vagina

  e

  Introitus
  Explanation: The pelvic diaphragm is made of several muscles (levator ani, puborectalis, obturator internus) and it lies at the level of the bladder neck, external anal sphincter and lower 1/3 of the vagina. There are also a number of ligaments that support the cervix (pubocervical, sacrocervical and cardinal), which may be damaged during childbirth.
• 25
  In a nulliparous woman, what is the normal position for the uterus?
  Difficulty: Medium     Topic: Uterine position
  a

  Anteverted, anteflexed

  b

  Anteverted, retroflexed

  c

  Retroverted, anteflexed

  d

  Retroverted, neutral flexion

  e

  Retroverted, retroflexed
  Explanation: The position of the uterus is described using two terms. The angle between the body of the uterus and the vagina determines if the uterus is anteverted (angled forwards) or retroverted. The angle between the cervix and the uterine fundus determines if it is anteflexed (bent forwards) or retroflexed. Anteverted, anteflexed is normal before pregnancy.
• 26
  Which two vessels anastamose to supply the uterus?
  Difficulty: Easy     Topic: Uterine blood supply
  a

  Inferior epigastric and ovarian arteries

  b

  Internal pudendal and ovarian arteries

  c

  Internal pudendal and uterine arteries

  d

  Ovarian and uterine arteries

  e

  Uterine and inferior epigastric arteries
  Explanation: The uterine artery ascends from internal iliac arteries and passes superior to the ureters then along the lateral aspect of the uterus. The ovarian arteries run in the broad ligament between the ovary and the uterus then descend to anastamose with the uterine arteries.
• 27
  Where do the ureters pass in relation to the female reproductive organs?
  Difficulty: Medium     Topic: Ureters
  a

  Anterior to the cervix

  b

  Anterior to the uterine fundus

  c

  Inferior to the uterine arteries

  d

  Superior to the Fallopian tubes

  e

  Superior to the uterine veins
  Explanation: The ureters run along the posterior abdominal wall, descending approximately in line with the medial border of psoas major. They cross the pelvic brim and pass posterior to the uterus as they head towards the bladder. They run inferior to the uterine arteries and then approach the bladder from the posterior aspect.
• 28
  Where is the cervical transformation zone located?
  Difficulty: Medium     Topic: Transformation zone
  a

  At the internal os

  b

  In the anterior fornix

  c

  In the endocervix

  d

  In the posterior fornix

  e

  On the ectocervix
  Explanation: The transformation zone is the area on the ectocervix close to the external os where the epithelium changes from stratified squamous (of the vagina) to simple columnar (of the endocervix). There is a high rate of dysplasia here and it is where cervical cancer develops.
• 29
  Which vessel supplies blood to breast tissue?
  Difficulty: Medium     Topic: Breast supply
  a

  2nd-6th posterior intercostal arteries

  b

  Axillary artery

  c

  Internal thoracic artery

  d

  Subclavian artery

  e

  Subcostal artery
  Explanation: The breasts are supplied by the internal thoracic artery, which descends inside the thoracic cage, giving rise to the anterior intercostal arteries and branches to the breast. The breast overlies ribs 2-6 but it is anterior branches that supply the tissue. The subcostal artery is below rib 12.
• 30
  What form of male gamete is found in the basal compartment of seminiferous tubules?
  Difficulty: Easy     Topic: Seminiferous tubules
  a

  Primary spermatocyte

  b

  Secondary spermatocyte

  c

  Spermatid

  d

  Spermatogonia

  e

  Spermatozoa
  Explanation: Seminiferous tubules are separated into basal and adluminal compartments by tight junctions between Sertoli cells. Proliferation of germ cells (spermatogonia) occurs in the basal compartment. Division of spermatocytes occurs in the adluminal compartment. Spermatids undergo spermiation within the tubule lumen.
• 31
  In women, what factor causes negative feedback on release of GnRH?
  Difficulty: Easy     Topic: GnRH 2
  a

  FSH

  b

  GnRH

  c

  Inhibin

  d

  LH

  e

  Oestradiol
  Explanation: GnRH is almost entirely controlled by oestradiol in women. GnRH (from the hypothalamus) acts on gonadotrophin cells in the anterior pituitary to cause release of LH and FSH. These together cause increased oestrogen from the ovaries, which acts at the hypothalamus to reduce GnRH (it also reduces LH at the pituitary).
• 32
  How is inhibin produced?
  Difficulty: Medium     Topic: Inhibin
  a

  Action of FSH on granulosa cells

  b

  Action of FSH on theca externa cells

  c

  Action of FSH on theca interna cells

  d

  Action of LH on theca externa cells

  e

  Action of LH on theca interna cells
  Explanation: Inhibin is a peptide produced by granulosa cells in mature follicles and the corpus luteum in response to FSH. Inhibin acts on the anterior pituitary to inhibit FSH production.
• 33
  What is the role of FSH in oestradiol production?
  Difficulty: Medium     Topic: Oestrogen production
  a

  Increases 5-alpha-reductase activity in granulosa cells

  b

  Increases 5-alpha-reductase activity in theca cells

  c

  Increases aromatase activity in granulosa cells

  d

  Increases aromatase activity in theca cells

  e

  Increases conversion of cholesterol to pregnenolone
  Explanation: Oestradiol is produced by LH acting on theca interna cells to stimulate conversion of cholesterol to pregnenolone. This, and other steroid derivatives diffuse into granulosa cells where FSH act to increase activity in aromatase. This enzyme is needed for conversion of androgens to oestrogen derivatives.
• 34
  What hormone profile would be seen in primary ovarian failure?
  Difficulty: Easy     Topic: Ovarian failure
  a

  High oestrogen, high FSH, high LH

  b

  High oestrogen, low FSH, low LH

  c

  Low oestrogen, high FSH, high LH

  d

  Low oestrogen, low FSH, high LH

  e

  Low oestrogen, low FSH, low LH
  Explanation: In ovarian failure there is low oestrogen (and progesterone). Primary ovarian failure refers to damage to the ovaries but intact pituitary/hypothalamus. The lack of oestrogen causes a loss of negative feedback and high levels of FSH and LH. Secondary ovarian failure would occur in pituitary damage, causing low FSH and LH with consequently low oestrogen due to a lack of stimulation.
• 35
  What does oogenesis refer to development of?
  Difficulty: Easy     Topic: Oogenesis 1
  a

  From primary oocytes to secondary oocytes

  b

  From primordial germ cells to primary oocytes

  c

  From primordial germ cells to secondary oocytes

  d

  Ovarian follicles

  e

  Ovarian tissue
  Explanation: Primordial germ cells (PGC) are a group of cells in the embryo that later go on form oocytes in women or spermatids in men. PGC migrate to the genital ridge in lateral plate mesoderm then proliferate, then divide to form oogonia. When oogonia enter meiosis then they are termed oocytes.
• 36
  When does the 1st meiotic block occur?
  Difficulty: Easy     Topic: Oogenesis 2
  a

  In utero

  b

  As a neonate

  c

  At menarche

  d

  During reproductive years

  e

  At menopause
  Explanation: Primary oocytes enter meiosis during foetal life but pause at Prophase 1, which is known as the first meiotic block. They stay at this stage until they continue oogenesis just before ovulation, which may be at any time during the reproductive years. Secondary oocytes are those that have completed the first meiotic division. They pause at metaphase 2 - this is only completed at zygote formation.
• 37
  What term is given to the follicle and oocyte immediately before ovulation?
  Difficulty: Medium     Topic: Oogenesis 3
  a

  Primary oocyte, primary follicle

  b

  Primary oocyte, secondary follicle

  c

  Secondary oocyte, secondary follicle

  d

  Secondary oocyte, tertiary follicle

  e

  Tertiary oocyte, tertiary follicle
  Explanation: From birth till puberty all gametes are primary oocytes, surrounded by primordial follicles. Each menstrual cycle several follicles enter folliculogenesis and develop into primary and secondary follicles. They compete for LH in late follicular phase, such that only the follicle with the highest LH-receptor density continues development into a tertiary (Graafian) follicle. At this time the primary oocyte continues into meiosis 2 to become a secondary oocyte. There is no tertiary oocyte.
• 38
  In a 28-day menstrual cycle, approximately when is LH highest?
  Difficulty: Easy     Topic: Menstrual cycle 1
  a

  Day 1

  b

  Day 7

  c

  Day 13

  d

  Day 15

  e

  Day 21
  Explanation: A 28-day cycle consists of 14-days follicular phase plus 14-days luteal phase. In late follicular phase oestrogen changes its feedback at the pituitary from negative to positive. This causes increased LH in response to high oestrogen. Follicle development permits increased oestrogen production and consequently a peak in LH, which stimulates final follicular development and ovulation.
• 39
  In a 28-day menstrual cycle, approximately when is progesterone highest?
  Difficulty: Easy     Topic: Menstrual cycle 2
  a

  Day 1

  b

  Day 7

  c

  Day 13

  d

  Day 15

  e

  Day 21
  Explanation: In the luteal phase, progesterone and oestrogen are made by the corpus luteum, which has a preference for producing progesterone and results in high levels. This is required for formation of a glandular endometrium. However there is negative feedback at the pituitary, causing low LH and FSH and in the absence of hCG the corpus luteum regresses spontaneously, with a fall in progesterone by day 27.
• 40
  What is the role of progesterone in the luteal phase?
  Difficulty: Easy     Topic: Menstrual cycle 3
  a

  Increase endometrial proliferation

  b

  Increase endometrial vascularity

  c

  Reduce endometrial mucus production

  d

  Reduce endometrial proliferation

  e

  Reduce GnRH production
  Explanation: In the luteal phase, the follicular remnants form the corpus luteum. It produces high levels of oestrogen and progesterone initially however requires LH (or hCG made by a fertilised ovum) to survive. The oestrogen causes proliferation of endometrial cells, and then progesterone increases the vascularity by stimulating angiogenesis, vessel dilatation and increased mucus production. The sharp fall in progesterone at day 27-28 causes vessel constriction and results in menses.
• 41
  In men, how is testosterone produced?
  Difficulty: Easy     Topic: Testosterone
  a

  Action of FSH on Leydig cells

  b

  Action of FSH on Sertoli cell

  c

  Action of LH on granulosa cells

  d

  Action of LH on Leydig cells

  e

  Action of LH on Sertoli cells
  Explanation: Testosterone is produced by LH acting on leydig cells, that lie between seminiferous tubules, to increase conversion of cholesterol to pregnenolone. FSH acts on Sertoli cells to stimulate spermatozoa development and production of inhibin for negative feedback on FSH.
• 42
  In men, where is most dihydroxytestosterone produced?
  Difficulty: Easy     Topic: Dihydroxytestosterone
  a

  Adipose

  b

  Leydig cells

  c

  Sertoli cells

  d

  Spermatids

  e

  Spermatozoa
  Explanation: Dihydroxytestosterone (DHT) is production by the action of 5-alpha-reductase on testosterone. FSH acts on Sertoli cells to increase activity of 5-alpha-reductase, which converts testosterone from leydig cells into the more active DHT.
• 43
  What does spermiogenesis refer to development of?
  Difficulty: Easy     Topic: Spermiation 1
  a

  Primordial germ cells into spermatids

  b

  Primordial germ cells into spermatozoa

  c

  Primordial germ cell proliferation

  d

  Spermatids into spermatozoa

  e

  Testes
  Explanation: Spermatogenesis is the development of mature spermatozoa from primordial germ cells (PGC), and is in 3 phases: proliferation, meiosis and differentiation. PGC proliferate in utero to form spermatogonia. These undergo further division at puberty into spermatocytes, which divide by meiosis to form spermatids. Spermatozoa are formed by differentiation of spermatids and this process is known as spermiation.
• 44
  In what manner is GnRH released from the hypothalamus in adults?
  Difficulty: Hard     Topic: GnRH 1
  a

  Continuous release

  b

  High in morning, low at night

  c

  Low in morning, high at night

  d

  Pulsatile release only at night

  e

  Pulsatile release throughout the day
  Explanation: GnRH is released in a pulsatile fashion with peaks each 1-2 hours. This begins at puberty and is initially only a night however it then becomes present throughout the day. Cortisol peaks in the morning and is low at night.
• 45
  Which of the following is NOT part of spermiation?
  Difficulty: Medium     Topic: Spermiation 2
  a

  Acrosome development

  b

  Centriole migration

  c

  Flagellum formation

  d

  Nuclear condensation

  e

  Proliferation
  Explanation: Spermiation is the process of maturation of spermatids into spermatozoa, which involves several specialisations but there is no proliferation or increase in cell number. The acrosome is a modification of the lysosomes that surrounds the nucleus and contains hydrolytic enzymes. Centrioles migrate and then form a flagellum for sperm motility. The nucleus condenses and exchanges histones for protamines.
• 46
  How many spermatozoa are formed from one division of a spermatogonium?
  Difficulty: Hard     Topic: Male gamete production
  a

  4

  b

  16

  c

  64

  d

  128

  e

  256
  Explanation: There is a population of stem cells (As spermatogonia) that undergo asymmetrical mitosis to form one A1 spermatogonium and a further stem cell. The A1 spermatogonium undergoes 5 divisions, after which they are termed a B spermatogonium (x 32) that divide by mitosis again to become primary spermatocytes (x 64). Primary spermatocytes complete meiosis 1 to make secondary spermatocytes (x 124) and then meiosis 2 to form spermatids (x 256). Spermatids mature into spermatozoa.
• 47
  What does sexual determination refer to?
  Difficulty: Medium     Topic: Sexual determination
  a

  Development of secondary sexual characteristics

  b

  Menarche or first ejaculation

  c

  Presence of a Y-chromosome

  d

  Presence of ovaries or testes

  e

  Presence or absence of SRY
  Explanation: Sexual determination is whether or not there is the sex-determining region of Y-chromosome (SRY) present in the cells, not necessarily just a Y-chromosome. This is the only factor that is needed to determine whether testes or ovaries develop, and then these go on to form the hormones that are needed for development of the external genitalia. Puberty describes development of secondary sexual characteristics.
• 48
  What is the most important factor in determining development of external genitalia?
  Difficulty: Easy     Topic: External genitalia development
  a

  Dihydroxytestosterone

  b

  Oestradiol

  c

  Oestratriol

  d

  SRY

  e

  Testosterone
  Explanation: The external genitalia begins as undifferentiated structures: genital tubercle, urogenital fold and labioscrotal folds. In the presence of DHT (dihydroxytestosterone) they go on to form the male external genitalia. In the absence of DHT (regardless of other factors), the structures go on to form predominantly female external genitalia but testosterone does play some role in promoting male external development.
• 49
  What is required for development of male internal genitalia?
  Difficulty: Easy     Topic: Internal genitalia development
  a

  Mullerian inhibitory substance for regression of mesonephric ducts

  b

  No factors are required

  c

  Testosterone for persistence of paramesonephric ducts

  d

  Testosterone for persistence of Wolffian ducts

  e

  Testosterone for regression of Müllerian ducts
  Explanation: Internal reproductive development is driven by the sex-determining region on Y-chromosome (SRY). SRY drives testis development, which then produce Mullerian inhibitory substance (MIS) that causes degeneration of the Müllerian ducts (paramesonephric), which otherwise go on to form the female internal organs. Testicular production of testosterone is needed for persistence of the Wolffian (mesonephric) ducts that go on to form male internal structures.
• 50
  What hormones mediate development of pubic hair during puberty in women?
  Difficulty: Easy     Topic: Puberty
  a

  Androgens

  b

  Gonadotrophins

  c

  GnRH

  d

  Oestrogens

  e

  Progesterones
  Explanation: Development of pubic and axillary hair in both sexes is due to androgens (DHEA, androsteinedione, testosterone). Women produce androgrens in the ovaries and adrenals, which mediates these secondary sexual characteristics. Oestrogens mediate breast and genitalia development in women.
• 51
  What is the underlying pathology of congenital adrenal hyperplasia?
  Difficulty: Hard     Topic: Congenital adrenal hyperplasia
  a

  Reduced androgens, increased glucocorticoids

  b

  Reduced androgens, increased mineralocorticoids and glucocorticoids

  c

  Reduced glucocorticoids, increased mineralocorticoids

  d

  Reduced mineralocorticoids and androgens, increased glucocorticoids

  e

  Reduced mineralocorticoids and glucocorticoids, increased androgens
  Explanation: Congenital adrenal hyperplasia is caused by 21-hydroxylase deficiency, which prevents conversion of steroids into mineralocorticoids (aldosterone) or glucocorticoids (cortisol). Instead there are excess androgrens produced, which causes growth of ambiguous genitalia. There is a lack of negative feedback so there are high levels of ACTH that simulate adrenal hyperplasia.
• 52
  What is the genital phenotype of male patients who cannot produce any dihydroxytestosterone?
  Difficulty: Hard     Topic: DHT in development
  a

  Ambiguous internal, male external

  b

  Ambiguous internal and external

  c

  Female internal, male external

  d

  Male internal, ambiguous external

  e

  Male internal, female external
  Explanation: DHT is required only for development of male external genitalia. Testosterone and anti-mullerian hormone (from testes) is sufficient for male internal genitalia development. Therefore patients with 5-alpha-hydroxylase deficiency have male internal features but are ambiguous externally. Though, in theory, if they were to have zero 5-DHT they may have fully-female external genitalia, in reality there is some action of testosterone at the 5-DHT receptor, therefore the genitalia is ambiguous. This is unlike complete androgen insensitivity syndrome, where due to a defective androgen receptor the external genitalia is entirely female despite being XY karyotype.
• 53
  What is the genital phenotype of a male patient who is not able to respond to any androgen?
  Difficulty: Hard     Topic: Androgen insensitivity
  a

  Ambiguous internal, female external

  b

  Ambiguous internal, male external

  c

  Ambiguous internal and external

  d

  Female internal, ambiguous external

  e

  Male internal, ambiguous external
  Explanation: Androgens are needed for development of external genitalia and in the absence of this full female external genitalia develop. The presence of SRY (and testes) causes production of anti-Mullerian hormone, which blocks internal female structures but androgens are needed for full male development. These are the features of a patient with androgen insensitivity syndrome.
• 54
  On approximately what day after fertilisation does implantation occur?
  Difficulty: Easy     Topic: Implantation
  a

  Day 0

  b

  Day 2

  c

  Day 5

  d

  Day 9

  e

  Day 13
  Explanation: Fertilisation most commonly occurs in the ampulla of the Fallopian tube but it takes until day 9 (or 8-9) until implantation into the endometrium occurs.
• 55
  In a fully developed placenta, which tissue is in direct contact with maternal blood in intervillus spaces?
  Difficulty: Easy     Topic: Villus structure
  a

  Cytotrophoblast

  b

  Mesoderm connective tissue

  c

  Spiral artery endothelium

  d

  Syncytiotrophoblast

  e

  Villus endothelium
  Explanation: A tertiary villus has several layers: foetal capillaries (lined by endothelium) are the innermost structure, surrounded by mesodermal connective tissue, outside this is a layer is a cytotrophoblast with syncytiotrophoblast on the outside in contact with maternal blood.
• 56
  What is a placental cotyledon?
  Difficulty: Easy     Topic: Cotyledon
  a

  All branches from one stem villus

  b

  Area between two anchoring villi

  c

  Area drained by one terminal villus

  d

  Area supplied by one spiral artery

  e

  Quarter of a placenta
  Explanation: A cotyledon is the placental area that is drained by one stem villus. They can be seen macroscopically on top of the placenta. There are multiple spiral arteries for each cotyledon.
• 57
  What is the role of the extravillous trophoblast?
  Difficulty: Medium     Topic: Extravillous trophoblast
  a

  Increase resistance in spiral arteries

  b

  Increase spiral artery flow

  c

  Increase spiral artery smooth muscle

  d

  Reduce decidual inflammatory cells

  e

  Reduce decidual thickness
  Explanation: The extravillous trophoblast cells pass away from the villi and enter the decidua basalis along the maternal spiral arteries. They recruit inflammatory cells and then cause gradual breakdown of the vessel walls with loss of smooth muscle. Eventually the trophoblasts replace the endothelial cells.