MLT GlobePhysiology: Reproductive physiology
25 Physiology MCQs on Reproductive physiology with answers and explanations.
In human development, the term 'embryo' applies to the conceptus during which period?
The embryonic period covers the first 8 weeks, when organs form; from week 9 onward the conceptus is called a fetus.
Serum testosterone in men is produced mainly by which testicular cells under LH stimulation?
LH acts on Leydig cells between the seminiferous tubules to make testosterone. Sertoli cells respond to FSH and support spermatogenesis.
A semen analysis evaluates sperm made in the male gonads. These gonads are the:
The testes produce sperm and testosterone. Seminal vesicles and prostate are accessory glands adding fluid; the epididymis stores and matures sperm.
Which hormone is a gonadotrophin that stimulates the ovary?
LH and FSH are anterior pituitary gonadotrophins acting on the gonads. GnRH is hypothalamic, and oestradiol and progesterone are ovarian steroids.
Mid-cycle ovulation is triggered directly by a surge of which pituitary hormone?
Rising oestrogen from the dominant follicle exerts positive feedback, producing the LH surge that causes follicle rupture about 36 hours later. Progesterone rises only after ovulation.
A breastfeeding mother notices milk flowing when her baby starts to suckle. Which hormone causes this milk ejection?
Suckling triggers oxytocin release from the posterior pituitary, contracting myoepithelial cells to eject milk. Prolactin controls milk production, not its release.
Oxytocin ejects milk by contracting which cells surrounding the mammary alveoli?
Myoepithelial cells wrap around the alveoli and ducts and contract in response to oxytocin. The secretory epithelial cells make the milk but do not expel it.
The single diploid cell formed when a sperm fuses with a secondary oocyte is the:
Fertilisation produces a zygote. Its cleavage forms a morula and later a blastocyst, which implants.
Which hormone's release during labour is amplified by a positive feedback loop?
Cervical stretch triggers oxytocin release, which strengthens contractions and further stretches the cervix until delivery. Most other hormones are controlled by negative feedback.
Fertilisation of a secondary oocyte normally occurs in which part of the female tract?
The oocyte is fertilised in the ampulla of the uterine tube; the zygote then travels to the uterus and implants as a blastocyst about a week later.
A urine pregnancy test detects which hormone made by the placental syncytiotrophoblast?
Syncytiotrophoblast secretes hCG early in pregnancy to maintain the corpus luteum; it is the basis of pregnancy tests. The placenta also makes oestrogen and progesterone.
The period during which a person becomes capable of sexual reproduction is called:
Puberty is the whole process of attaining reproductive capacity. Menarche is only the first menstrual period, a single event within female puberty.
Rising serum progesterone after ovulation comes mainly from the:
After ovulation the ruptured follicle becomes the corpus luteum, which secretes progesterone and oestrogen. The corpus albicans is its non-secreting scar.
A semen analysis report lists the following. Which value is abnormal?
Normal semen is slightly alkaline (pH 7.2 or higher); acidic semen suggests seminal vesicle obstruction or absence. The other values exceed the WHO lower reference limits.
In the secretory (luteal) phase of the menstrual cycle, which hormone mainly prepares the endometrium for implantation?
After ovulation the corpus luteum secretes large amounts of progesterone (with oestrogen), making endometrial glands secretory and vascular. FSH dominates the early follicular phase instead.
In the luteal phase, why do new ovarian follicles normally fail to develop?
Oestrogen and progesterone from the corpus luteum (with inhibin) exert negative feedback on the hypothalamus and anterior pituitary, keeping FSH and LH low until the corpus luteum regresses.
In the male, FSH acts on Sertoli cells in the seminiferous tubules to:
FSH stimulates Sertoli cells to nurture developing sperm and make androgen-binding protein. LH, not FSH, stimulates Leydig cells to secrete testosterone.
Which hormone pattern is expected in a postmenopausal woman's serum?
With ovarian follicles exhausted, oestradiol and inhibin fall, removing negative feedback, so FSH (especially) and LH rise sharply. Raised FSH is a laboratory marker of menopause.
The acrosome cap on the sperm head contains:
The acrosome is a lysosome-like vesicle holding enzymes such as hyaluronidase and acrosin, released during the acrosome reaction. Mitochondria lie in the midpiece.
Why do the testes lie in the scrotum? Spermatogenesis works best at about:
Normal sperm production needs a temperature about 2-3 °C below core. That is why undescended testes (cryptorchidism) have impaired spermatogenesis.