Human Reproduction ISC Class 12 Biology: Notes and Questions

What Human Reproduction is about

Weightage: Human Reproduction is part of the unit Reproduction, which carries 16 of the 70 marks in the ISC Biology Paper 1 (Theory), shared with 2 other chapters. Questions on it can appear in any section of the paper.Source: CISCE ISC Biology syllabus, examination year 2027, distribution of marks

Key concepts

Male reproductive system and the testis

Testes: in the scrotum, which keeps them 2-2.5 °C below body temperature, needed for spermatogenesis. Each testis is covered by a dense tunica albuginea and divided into about 250 testicular lobules, each with 1-3 highly coiled seminiferous tubules. Seminiferous tubule (T.S.): lined by spermatogonia (male germ cells) on the basement membrane, which divide to form sperms (stages arranged from outside inwards: spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, sperms near the lumen); tall Sertoli cells (nurse cells) nourish the developing germ cells. Interstitial spaces between tubules contain blood vessels and Leydig (interstitial) cells, which secrete androgens (testosterone). Duct system: seminiferous tubules → rete testis → vasa efferentia → epididymis (along the back of the testis; sperm storage and maturation) → vas deferens (loops over the bladder) → joins the duct of the seminal vesicle to form the ejaculatory duct → urethra → urethral meatus. Accessory glands: paired seminal vesicles (fructose, prostaglandins, clotting proteins; most of the semen volume), single prostate (milky alkaline fluid, citrate, enzymes), paired bulbourethral (Cowper's) glands (mucus, lubrication). Semen = sperms + seminal plasma. Penis: erectile tissue; tip is the glans penis covered by the foreskin.

Worked example

Why are the testes located in the scrotum outside the abdominal cavity? What would happen if they failed to descend?

Try it first, then show the solutionSolution

1. The scrotum keeps the testes about 2-2.5 °C below normal body temperature, the temperature needed for spermatogenesis.
2. Undescended testes (cryptorchidism) remain at body temperature, so sperm production fails and the man is sterile (hormone secretion continues).

Answer: Lower temperature for spermatogenesis; otherwise sterility

Female reproductive system and the ovary

Ovaries: a pair of almond-shaped organs (2-4 cm) in the lower abdomen, held by ligaments; they produce ova and the hormones oestrogen and progesterone. Ovary (T.S.): covered by germinal epithelium; inside, the ovarian stroma has a peripheral cortex containing follicles at different stages and a central medulla with blood vessels. Follicles: primordial (primary oocyte with a layer of flat granulosa cells), primary (cuboidal granulosa cells), secondary (more granulosa layers and a theca), tertiary (fluid-filled antrum, theca interna and externa), and the mature Graafian follicle (secondary oocyte surrounded by zona pellucida and corona radiata, on a mound of cells, the cumulus). After ovulation the ruptured follicle becomes the corpus luteum, which degenerates to the corpus albicans if no pregnancy occurs. Oviduct (about 10-12 cm): infundibulum with finger-like fimbriae (collect the ovum at ovulation), ampulla (site of fertilisation), isthmus joining the uterus. Uterus: inverted pear shape; wall of perimetrium, thick muscular myometrium (strong contractions in labour) and glandular endometrium (cyclical changes; implantation). Cervix opens into the vagina; the cervical canal and vagina form the birth canal. External genitalia: mons pubis, labia majora and minora, clitoris, hymen. Mammary glands: glandular tissue in 15-20 mammary lobes with alveoli secreting milk; ducts → mammary ampulla → lactiferous duct → nipple.

Worked example

Name the part of the oviduct where (a) the ovum is collected, (b) fertilisation usually occurs, (c) the oviduct joins the uterus.

Try it first, then show the solutionSolution

1. (a) Infundibulum with fimbriae.
2. (b) Ampulla; (c) isthmus.

Answer: Infundibulum, ampulla, isthmus

Spermatogenesis, spermiogenesis and the sperm

Begins at puberty under hormones. Multiplication: spermatogonia (2n = 46) divide mitotically. Growth: some become primary spermatocytes (2n). Maturation: each primary spermatocyte completes meiosis I to form two secondary spermatocytes (n = 23), which complete meiosis II to form four spermatids (n). Spermiogenesis: transformation of the round spermatid into a motile sperm (no division): acrosome from the Golgi body, nucleus condenses, mitochondria gather in the middle piece, tail forms. Spermiation: release of sperms from the Sertoli cells into the lumen of the seminiferous tubule. Hormonal control: at puberty the hypothalamus increases GnRH, which makes the anterior pituitary release LH (acts on Leydig cells: androgen secretion, which stimulates spermatogenesis) and FSH (acts on Sertoli cells: factors that help spermiogenesis). Sperm structure: head with an elongated haploid nucleus and the cap-like acrosome (enzymes to penetrate the ovum); neck; middle piece with many mitochondria (energy for swimming); tail. The whole sperm is covered by plasma membrane. A normal ejaculate has 200-300 million sperms; at least 60% should have normal shape and 40% vigorous motility for normal fertility.

Worked example

How many sperms are formed from (a) 20 primary spermatocytes, (b) 20 secondary spermatocytes, (c) 20 spermatids?

Try it first, then show the solutionSolution

1. Each primary spermatocyte → 2 secondary → 4 spermatids → 4 sperms.
2. (a) 20 × 4 = 80. (b) 20 × 2 = 40. (c) 20 × 1 = 20 (spermiogenesis has no division).

Answer: 80, 40, 20

Oogenesis and the ovum

Before birth: millions of oogonia form in each foetal ovary by mitosis; they enter meiosis I and arrest in prophase I as primary oocytes, each in a primordial follicle. Many degenerate (atresia), so at puberty only about 60 000-80 000 primary follicles remain in each ovary. From puberty: each month a follicle grows (primary → secondary → tertiary). In the tertiary follicle the primary oocyte completes meiosis I unequally, forming a large haploid secondary oocyte and a tiny first polar body. The Graafian follicle ruptures and releases the secondary oocyte (ovulation). Meiosis II is completed only if a sperm enters, giving the ovum and a second polar body. So one primary oocyte gives one ovum (and two or three polar bodies). Ovum structure: large cell with abundant cytoplasm (little yolk: alecithal) and a haploid nucleus; surrounded by the zona pellucida (glycoprotein layer) and the corona radiata (follicle cells). Hormonal control: FSH stimulates follicle growth and oestrogen secretion; the LH surge triggers ovulation and corpus luteum formation.

Worked example

A woman reaches menarche at 12 and conceives for the first time at 25, with regular 28-day-like monthly cycles. About how many secondary oocytes has she ovulated before conceiving (one per cycle)?

Try it first, then show the solutionSolution

1. Ovulation occurs once a month from puberty: 25 − 12 = 13 years.
2. 13 × 12 = 156 ovulations (counting from menarche, not from birth).

Answer: About 156

Menstrual cycle, menarche and menopause

The menstrual cycle is the cyclical change in the ovary and uterus of primate females, about 28/29 days. Menarche: the first menstruation at puberty; menopause: permanent stop at about 50 years. Phases: (1) Menstrual phase (days 1-5): if the ovum was not fertilised, the corpus luteum degenerates, progesterone falls, and the endometrium breaks down; blood and tissue flow out. (2) Follicular (proliferative) phase (days 5-13): FSH (and LH) rise; primary follicles grow into a Graafian follicle that secretes oestrogen; oestrogen makes the endometrium regenerate and proliferate. (3) Ovulatory phase (about day 14): LH and FSH peak (the LH surge) in mid-cycle; the Graafian follicle ruptures and releases the secondary oocyte (ovulation). (4) Luteal (secretory) phase (days 15-28): the ruptured follicle becomes the corpus luteum (under LH), which secretes large amounts of progesterone; the endometrium becomes thick, glandular and vascular, and its glands secrete fluid: hence both names, 'luteal' (corpus luteum) and 'secretory' (endometrial secretion). Progesterone maintains the endometrium for implantation. If pregnancy occurs, the corpus luteum persists and cycles stop. Oestrous vs menstrual cycle: oestrous cycles occur in non-primate mammals (cow, dog); females are receptive only during oestrus ('heat'); there is no menstrual bleeding; the endometrium is reabsorbed. Menstrual cycles occur in primates; females are receptive throughout; the endometrium is shed with bleeding.

Worked example

Explain why menstruation begins when the progesterone level falls at the end of the luteal phase.

Try it first, then show the solutionSolution

1. If no embryo implants, there is no hCG to maintain the corpus luteum, so it degenerates into the corpus albicans.
2. Progesterone (and oestrogen) levels fall; the thick, secretory endometrium is no longer maintained, and its blood vessels constrict.
3. The endometrium breaks down and is shed with blood through the vagina: the menstrual flow of the next cycle.

Answer: Progesterone withdrawal after the corpus luteum degenerates causes the endometrium to break down

Fertilisation: physico-chemical events

Fertilisation happens in the ampulla of the oviduct, within about 24 hours of ovulation. Capacitation: sperms in the female tract become able to fertilise over 5-6 hours: cholesterol and glycoproteins are removed from the membrane over the head and acrosome, the membrane becomes more permeable, and Ca²⁺ ions enter the sperm, increasing the permeability of the acrosomal membrane and the beating of the tail. Acrosome reaction: on contact with the zona pellucida, the acrosome releases lytic enzymes (sperm lysins, e.g. hyaluronidase dissolves the corona radiata cement; acrosin digests the zona) so the sperm can reach the oocyte membrane. Fertilizin-antifertilizin reaction: fertilizin (glycoprotein on the egg surface) binds species-specifically with antifertilizin on the sperm head, so sperms adhere to the egg (species recognition). Entry and block to polyspermy: contact with the oocyte membrane triggers the cortical reaction: cortical granules release contents that change the zona pellucida (zona reaction), forming a fertilisation membrane that blocks entry of more sperms. Activation: sperm entry makes the secondary oocyte complete meiosis II (ovum + second polar body); male and female pronuclei fuse (karyogamy) to give the diploid zygote. Sex determination: the ovum carries X; a sperm carrying X gives a female (XX), one carrying Y a male (XY).

Worked example

Arrange in the correct order and state where each happens: cortical reaction, capacitation, karyogamy, acrosome reaction.

Try it first, then show the solutionSolution

1. Capacitation: in the female reproductive tract, before the sperm meets the egg.
2. Acrosome reaction: at the zona pellucida, releasing lysins.
3. Cortical reaction: in the oocyte cortex just after one sperm enters, blocking polyspermy.
4. Karyogamy: fusion of the male and female pronuclei inside the egg, giving the zygote.

Answer: Capacitation → acrosome reaction → cortical reaction → karyogamy

Cleavage, blastocyst, implantation and foetal development

The zygote divides by mitosis (cleavage) as it moves down the oviduct: 2, 4, 8, 16 cells (blastomeres); the 8-16 celled embryo is a morula. The morula forms a blastocyst: an outer layer of trophoblast and an inner group of cells, the inner cell mass, around a cavity. The trophoblast attaches to the endometrium and the blastocyst becomes embedded in it: implantation (about 7 days after fertilisation), leading to pregnancy. The trophoblast forms chorionic villi that interdigitate with uterine tissue to form the placenta. The inner cell mass differentiates into the ectoderm, mesoderm and endoderm (and contains stem cells able to give all tissues and organs). Milestones: end of 1 month: heart forms (first sign of growing foetus is the heartbeat); end of 2nd month: limbs and digits develop; end of 12 weeks (first trimester): most major organ systems formed, limbs and external genital organs well developed; 5th month: first movements of the foetus and appearance of hair on the head; end of 24 weeks (second trimester): body covered with fine hair, eyelids separate and eyelashes form; end of 9 months: foetus fully developed, ready for delivery.

Worked example

Distinguish between a morula and a blastocyst. Which part of the blastocyst attaches to the endometrium, and which part forms the embryo?

Try it first, then show the solutionSolution

1. Morula: a solid ball of 8-16 blastomeres formed by cleavage in the oviduct.
2. Blastocyst: a hollow stage with an outer layer, the trophoblast, and an inner cell mass on one side of a cavity.
3. The trophoblast attaches to the endometrium (implantation); the inner cell mass gives rise to the embryo.

Answer: Solid vs hollow; trophoblast attaches, inner cell mass forms the embryo

Placenta functions, parturition and lactation (elementary)

Placenta functions (structure and types not required): structural and functional link between embryo and mother via the umbilical cord; supplies oxygen and nutrients and removes CO₂ and wastes by diffusion (maternal and foetal blood do not mix); acts as a barrier to many harmful substances and passes some antibodies; works as an endocrine tissue secreting hCG (human chorionic gonadotropin, maintains the corpus luteum; detected in pregnancy tests), hPL (human placental lactogen), oestrogens, progestogens and relaxin (late pregnancy). During pregnancy maternal levels of oestrogens, progestogens, cortisol, prolactin and thyroxine also rise. Gestation in humans: about 9 months. Parturition (birth): the fully developed foetus and placenta send signals that trigger mild uterine contractions, the foetal ejection reflex; this makes the maternal pituitary release oxytocin, which causes stronger contractions, stimulating more oxytocin (positive feedback) until the baby is expelled through the birth canal, followed by the placenta. Ovarian/placental hormones in parturition: relaxin softens the pubic symphysis and cervix to widen the birth canal; a rise in oestrogen relative to progesterone increases oxytocin receptors and uterine contractility, while the fall in the progesterone block allows contractions. Lactation: the mammary glands produce milk towards the end of pregnancy. Prolactin (anterior pituitary) stimulates milk production; oxytocin causes milk ejection (let-down) during suckling. The first milk, colostrum, is rich in antibodies (IgA), giving the newborn passive immunity. During breastfeeding high prolactin suppresses GnRH/LH and hence ovulation, so menstruation is absent (lactational amenorrhoea).

Worked example

Name two hormones that appear in a woman's blood only during pregnancy and state where each is produced.

Try it first, then show the solutionSolution

1. hCG (human chorionic gonadotropin): produced by the trophoblast and then the placenta; it maintains the corpus luteum.
2. hPL (human placental lactogen): produced by the placenta; it helps prepare the mammary glands and alters maternal metabolism.

Answer: hCG and hPL, both from the placenta (trophoblast)

Human Reproduction in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Male and Female Reproductive Systems
• Gametogenesis: Spermatogenesis and Oogenesis
• Menstrual Cycle and Hormonal Control

Human Reproduction: key facts

Spermatogenesis count

$1\text{primary spermatocyte}\to 2\text{secondary spermatocytes}\to 4\text{spermatids}\to 4\text{sperms}$

Spermiogenesis involves no division.

Oogenesis count

$1\text{primary oocyte}\to 1\text{secondary oocyte}+\text{polar body}\to 1\text{ovum}+\text{polar body}$

Meiosis II only after sperm entry.

Chromosome numbers

$\text{spermatogonium, primary spermatocyte, primary oocyte, zygote}=46;\text{secondary spermatocyte, spermatid, sperm, secondary oocyte, ovum}=23$

Meiosis I halves the number.

Hormone axis

$\text{GnRH (hypothalamus)}\to \text{LH, FSH (anterior pituitary)}\to \text{gonads}$

Male: LH → Leydig cells; FSH → Sertoli cells.

Ovulation day

$\text{ovulation day}\approx \text{cycle length}-14$

Luteal phase is fairly constant (about 14 days).

Sex determination

$\text{X ovum}+\text{X sperm}=\text{XX (girl)};\text{X ovum}+\text{Y sperm}=\text{XY (boy)}$

Probability of each is 1/2 per pregnancy.

Early development

$\text{zygote}\to \text{cleavage}\to \text{morula (8-16 cells)}\to \text{blastocyst}\to \text{implantation}$

Implantation about 7 days after fertilisation.

Human Reproduction: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the board asks Human Reproduction

The question patterns to expect, and the method that works for each.

Tricks to remember Human Reproduction

Short memory aids. Say each one aloud once, then use it on a question the same day.

• SEVEN UP

  Sperm path: Seminiferous tubules, Epididymis, Vas deferens, Ejaculatory duct, (Nothing), Urethra, Penis.

  Use it when: Male duct system.

• LH for Leydig, FSH for Sertoli

  L-L and S-S (FSH starts with F, but think Sertoli Supports).

  Use it when: Hormonal control of spermatogenesis.

• MFOL

  Menstrual, Follicular, Ovulatory, Luteal: 'My Friends Often Laugh'.

  Use it when: Order of menstrual phases.

• One oocyte, one egg

  Primary spermatocyte → 4 sperms; primary oocyte → 1 ovum.

  Use it when: Gamete counts.

• CAP-ACRO-CORTICAL

  Capacitation (in tract), Acrosome reaction (at zona), Cortical reaction (after entry).

  Use it when: Sequence of fertilisation events.

Human Reproduction: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section D style)

Read the situation, then answer every part. In the board paper this is a 5-mark question split into 1 + 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Human Reproduction

The slips examiners see most often, and what to write instead.

• ✗Mistake: Wrong section in diagrams

  CISCE examiners' comments, 2024 and 2025: for T.S. of ovary, candidates drew L.S. of a plant ovule or only a Graafian follicle; for T.S. of testis, they drew L.S. of testis, T.S. of ovary or a sperm; labels were unclear and label lines overlapped.

  Wrong working

  A single Graafian follicle labelled 'ovary'.

  Right working

  Whole ovary with germinal epithelium, follicles at all stages, corpus luteum and stroma.

  ✓Do this: Practise each of the two T.S. diagrams until you can draw them in five minutes.

  Usually costs: 2-3 marks.

• ✗Mistake: Confusing stages and terms of spermatogenesis

  CISCE examiners' comments, 2024: candidates wrote spermatogonia instead of spermatocyte and spermatogenesis instead of spermiogenesis; they also confused the functions of LH and FSH when explaining the luteal phase.

  Wrong working

  Spermatid → sperm is spermatogenesis.

  Right working

  Spermatid → sperm is spermiogenesis (part of spermatogenesis); release is spermiation.

  ✓Do this: Learn the five terms in order: spermatogonium, spermatocyte I, spermatocyte II, spermatid, spermatozoon.

  Usually costs: 1 mark each.

• ✗Mistake: Naming pituitary hormones as ovarian hormones

  CISCE examiners' comments, 2025: asked for two ovarian hormones in parturition, candidates named oxytocin, FSH and LH.

  Wrong working

  Oxytocin and LH.

  Right working

  Relaxin and oestrogen (with the fall of progesterone).

  ✓Do this: Sort hormones by source before answering.

  Usually costs: 1-2 marks.

• ✗Mistake: Counting ovulations from birth

  CISCE examiners' comments, 2025: for a woman who reached puberty at 14 and conceived at 30, candidates counted from birth instead of from puberty to conception.

  Wrong working

  30 × 12 = 360

  Right working

  (30 − 14) × 12 = 192

  ✓Do this: Ovulation starts at menarche.

  Usually costs: 1 mark.

Practice questions on Human Reproduction

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   Leydig cells are found in the:
   (a) seminiferous tubules
   (b) interstitial spaces of testis
   (c) epididymis
   (d) prostate

   Hint

   Between tubules.

   Answer

   (b)

2. Q2 · 1 mark · MCQBoard level

   Which hormone surge causes ovulation?
   (a) FSH
   (b) progesterone
   (c) LH
   (d) prolactin

   Hint

   Mid-cycle peak.

   Answer

   (c) LH

3. Q3 · 1 mark · Assertion-reasonBoard level

   Assertion: A primary oocyte gives only one ovum.
   Reason: Both meiotic divisions in oogenesis are unequal, producing polar bodies.
   (a) Both true, Reason explains Assertion
   (b) Both true, Reason does not explain
   (c) Assertion true, Reason false
   (d) Both false

   Hint

   Cytoplasm goes to one cell.

   Answer

   (a)

4. Q4 · 1 mark · Very short answerBoard level

   What is the function of the bulbourethral glands?

   Hint

   Lubrication.

   Answer

   They secrete mucus that lubricates the penis (and neutralises acidity of the urethra).

5. Q5 · 2 marks · Short answerHarder board level

   How many sperms will be produced by 150 secondary spermatocytes, and how many ova by 150 primary oocytes?

   Hint

   2 per secondary spermatocyte; 1 per oocyte.

   Answer

   300 sperms; 150 ova.

6. Q6 · 2 marks · Short answerHarder board level

   Distinguish between oestrous and menstrual cycles (two points). Why is a cow receptive to the bull only for a short period?

   Hint

   Receptivity, bleeding and the timing of ovulation.

   Answer

   Oestrous: non-primate mammals; receptive only during heat; no bleeding, endometrium reabsorbed. Menstrual: primates; receptive throughout; endometrium shed with bleeding. A cow is receptive only during oestrus, the short phase around ovulation when oestrogen is high, so mating coincides with the release of the egg.

7. Q7 · 3 marks · Short answerHarder board level

   Describe the structure of the human sperm and give the function of the acrosome and middle piece.

   Hint

   Four parts.

   Answer

   Head (haploid nucleus, acrosome cap), neck, middle piece (mitochondria), tail; whole covered by plasma membrane. Acrosome: enzymes (lysins) to penetrate the ovum's coverings. Middle piece: mitochondria provide energy for tail movement.

8. Q8 · 2 marks · Short answerHarder board level

   Why is the corpus luteum essential in early pregnancy, and what happens to it if fertilisation does not occur?

   Hint

   Progesterone.

   Answer

   It secretes progesterone that maintains the endometrium for implantation and pregnancy (kept alive by hCG). Without fertilisation it degenerates into the corpus albicans; progesterone falls and menstruation begins.

9. Q9 · 2 marks · Short answerBoard level

   Trace the path of sperms from the seminiferous tubules to the outside.

   Hint

   Seven parts.

   Answer

   Seminiferous tubules → rete testis → vasa efferentia → epididymis → vas deferens → ejaculatory duct → urethra → urethral meatus.

10. Q10 · 2 marks · Short answerBoard level

    Name the hormones secreted by the placenta and give one function of hCG.

    Hint

    Four or five.

    Answer

    hCG, hPL, oestrogens, progestogens and relaxin. hCG maintains the corpus luteum in early pregnancy.

11. Q11 · 5 marks · Long answerHarder board level

    (a) Describe the menstrual cycle with reference to the ovarian and uterine events and hormones. [3]
    (b) What are menarche and menopause? [1]
    (c) Why does menstruation not occur during pregnancy? [1]

    Hint

    Four phases.

    Answer

    (a) Menstrual phase (days 1-5): endometrium breaks down as progesterone falls. Follicular phase (5-13): FSH/LH stimulate follicle growth; oestrogen from the follicle regenerates the endometrium. Ovulation (about day 14): LH surge ruptures the Graafian follicle. Luteal phase (15-28): corpus luteum secretes progesterone; endometrium thickens and becomes secretory. (b) Menarche: first menstruation at puberty; menopause: permanent cessation, about 50 years. (c) hCG keeps the corpus luteum active and later the placenta secretes progesterone, so the endometrium is maintained.

12. Q12 · 2 marks · Short answerHOTS / competency

    A blastocyst attaches to the wall of the oviduct instead of the uterus. Predict the outcome and explain why the uterus is the right site.

    Hint

    Ectopic pregnancy.

    Answer

    An ectopic (tubal) pregnancy: the oviduct wall cannot expand or form a proper placenta, so the embryo cannot develop normally and the tube may rupture (a medical emergency). The uterine endometrium is thick, vascular and prepared by progesterone, and the myometrium can expand.

13. Q13 · 2 marks · Short answerHOTS / competency

    Why is the ovum's meiosis II completed only after sperm entry, and what is the advantage?

    Hint

    Polar body; timing.

    Answer

    Sperm entry triggers the release of Ca²⁺ inside the oocyte, which restarts the cell cycle. Completing meiosis only on fertilisation means the haploid ovum forms exactly when its nucleus can fuse with the sperm's, and unfertilised oocytes do not waste resources.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Function of Sertoli cells?Show answer

   Nourish developing germ cells and support spermiogenesis (under FSH).

2. 2.What is capacitation?Show answer

   Changes in the sperm in the female tract that make it able to fertilise (membrane changes, Ca²⁺ entry).

3. 3.Where is the ovum collected after ovulation?Show answer

   By the fimbriae of the infundibulum.

4. 4.Hormone secreted by the corpus luteum?Show answer

   Progesterone (and some oestrogen).

5. 5.What is a morula?Show answer

   An 8-16 celled solid ball of blastomeres formed by cleavage.

6. 6.When does the foetal heart form?Show answer

   By the end of the first month.

7. 7.Hormone for milk ejection?Show answer

   Oxytocin.

8. 8.What is colostrum?Show answer

   The first milk after birth, rich in antibodies (IgA).

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you trace sperm from seminiferous tubule to urethral meatus?
• ☐Can you draw and label T.S. testis and T.S. ovary?
• ☐Can you name the stages and chromosome numbers in spermatogenesis and oogenesis?
• ☐Can you explain the four phases of the menstrual cycle and their hormones?
• ☐Can you describe capacitation, acrosome reaction and the block to polyspermy?
• ☐Can you list developmental milestones by week?
• ☐Can you give four functions of the placenta?
• ☐Can you explain the roles of oxytocin, relaxin and prolactin?

Human Reproduction: frequently asked questions