BiologyISC Class 12 · Human Reproduction

Human Male and Female Reproductive Systems: ISC Class 12 Biology

Updated 15 October 2026 · Fact-checked

The male system has a pair of testes in the scrotum, ducts (rete testis to urethra), accessory glands and the penis. The female system has a pair of ovaries, oviducts, uterus, cervix, vagina, external genitalia and mammary glands. ISC asks the functions of each organ and labelled T.S. of testis and ovary.

Follow the arrows: sperm pass from seminiferous tubules to the urethral meatus, and the three accessory glands add secretions along the way.

Illustration drawn for QuestionBuddy.

Understand Male and Female Reproductive Systems

Humans are sexually reproducing and viviparous. The primary sex organs (testes, ovaries) make gametes and hormones; accessory organs store, carry and nourish gametes and the embryo.

Male reproductive system (in the pelvic region).

Testes: a pair, outside the abdomen in the scrotum, which keeps them about 2-2.5 °C below internal body temperature, a condition needed for spermatogenesis. Each adult testis is oval, about 4-5 cm long and 2-3 cm wide, covered by a dense coat, and divided into about 250 testicular lobules, each with 1-3 highly coiled seminiferous tubules.
Seminiferous tubule: lined by male germ cells (spermatogonia), which form sperms, and Sertoli cells, which nourish the germ cells. Between tubules are interstitial spaces with blood vessels, immunologically competent cells and Leydig (interstitial) cells, which secrete androgens (testosterone).
Ducts (store and carry sperm): seminiferous tubules → rete testis → vasa efferentia → epididymis (along the back of the testis) → vas deferens (rises into the abdomen and loops over the urinary bladder) → joined by the duct of the seminal vesicle → ejaculatory duct → urethra → urethral meatus.
Accessory glands: paired seminal vesicles, single prostate, paired bulbourethral (Cowper's) glands. Their secretions form seminal plasma, rich in fructose, calcium and certain enzymes; bulbourethral secretion also lubricates the penis. Sperms + seminal plasma = semen. Sperms leaving the testis are not yet fully able to fertilise: the fluids added by the epididymis, vas deferens, seminal vesicles and prostate help them mature and become motile. Androgens keep these accessory ducts and glands functional.
Penis: external genitalia with special erectile tissue; its enlarged tip, the glans penis, is covered by the foreskin.

Female reproductive system (in the pelvic region).

Ovaries: primary female sex organs, one on each side of the lower abdomen, about 2-4 cm long, held to the pelvic wall and uterus by ligaments. They produce the ovum and steroid hormones. Each is covered by a thin epithelium (germinal epithelium) enclosing the ovarian stroma, divided into a peripheral cortex and an inner medulla.
Oviducts (Fallopian tubes): each about 10-12 cm: funnel-shaped infundibulum with finger-like fimbriae near the ovary (collect the ovum after ovulation) → wider ampulla (where fertilisation takes place, in the ampullary region) → narrow isthmus, which joins the uterus.
Uterus (womb): single, inverted-pear shaped, held by ligaments. Wall: outer thin perimetrium, middle thick smooth-muscle myometrium (strong contractions at delivery), inner glandular endometrium (cyclical changes in the menstrual cycle; site of implantation).
Cervix opens into the vagina; the cervical canal and vagina form the birth canal.
External genitalia: mons pubis (fatty cushion with pubic hair), labia majora, labia minora, hymen (partly covers the vaginal opening; not a reliable indicator of virginity, as it may tear in sport or persist after coitus) and clitoris (above the urethral opening).
Mammary glands: paired; glandular tissue in 15-20 mammary lobes with clusters of alveoli that secrete milk. Alveoli → mammary tubules → mammary duct → mammary ampulla → lactiferous duct → nipple.

Section through the ovary (follicles in the cortex). Primary follicle (primary oocyte with one layer of granulosa cells) → secondary follicle (more granulosa layers and a theca) → tertiary follicle (fluid-filled antrum, theca interna and externa) → Graafian follicle (secondary oocyte with zona pellucida) → after ovulation the corpus luteum → if no pregnancy, the corpus albicans.

Draw and label: T.S. of testis (seminiferous tubules). Checklist: two or three round tubules with basement membrane; spermatogonia on the basement membrane; primary spermatocytes, secondary spermatocytes, spermatids in layers towards the lumen; sperms with tails in the lumen; tall Sertoli cells; interstitial spaces with Leydig cells and a blood vessel. Do not confuse with T.S. of ovary or an L.S. of testis.

Draw and label: T.S. of mammalian ovary. Checklist: germinal epithelium; cortex and medulla; primary follicle; secondary follicle; Graafian follicle with antrum, theca, granulosa cells and secondary oocyte; corpus luteum; corpus albicans; blood vessels in the medulla. Draw the whole ovary, not only a Graafian follicle, and not an ovule of a plant.

Male and Female Reproductive Systems: key facts

Male duct route: $seminiferous tubules \to rete testis \to vasa efferentia \to epididymis \to vas deferens \to ejaculatory duct \to urethra$; Ejaculatory duct forms where the seminal vesicle duct joins the vas deferens.
Oviduct, ovary end to uterus end: $infundibulum (fimbriae) \to ampulla \to isthmus \to uterus$; Fertilisation in the ampullary region.
Uterine wall, outside in: $perimetrium \to myometrium \to endometrium$; Myometrium contracts at birth; endometrium changes every cycle.
Follicle sequence in the ovary: $primary \to secondary \to tertiary (antrum) \to Graafian \to corpus luteum \to corpus albicans$; Corpus albicans forms only if there is no pregnancy.
Milk route: $alveoli \to mammary tubules \to mammary duct \to mammary ampulla \to lactiferous duct \to nipple$; 15-20 mammary lobes per breast.

How to answer Male and Female Reproductive Systems questions

ISC sets labelled diagrams (T.S. testis, T.S. ovary), functions of named parts, and 'trace the path' or 'what would happen if' questions. Answer from structure to function.

1For a diagram, draw large and neat, label with straight lines that do not cross, and include at least five labels from the checklist.
2For 'function of' questions, give one precise job: Sertoli cells nourish germ cells; Leydig cells secrete androgens; fimbriae collect the ovum; myometrium contracts in labour.
3For 'trace the path', write every duct in order with arrows; one missing duct loses the mark.
4For 'what if' questions (blocked vas deferens, undescended testes, removed seminal vesicles), state which function is lost and the result.
5Separate primary sex organs (gametes and hormones) from accessory organs (transport, storage, nourishment).
6Use technical names: seminiferous tubule, interstitial cell, infundibulum, ampulla, endometrium.

Male and Female Reproductive Systems in real life

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

Scrotal temperature and sperm production

Suppose a long-distance truck driver who sits for ten hours a day in a hot cabin, wearing tight clothing, is told by a doctor that his sperm count is low and that he should change some habits.

Using the structure of the male reproductive system, explain the likely link and the advice.

Try it first, then show the solutionSolution

The testes lie outside the abdominal cavity in the scrotum, which keeps them about 2-2.5 °C cooler than internal body temperature.
This lower temperature is necessary for spermatogenesis in the seminiferous tubules.
Long hours of sitting in heat with tight clothing hold the scrotum close to the body and warm it, which can reduce sperm production.
Advice: take breaks, wear loose clothing and keep the cabin cooler so that scrotal temperature can stay lower.

Answer: Heat around the scrotum raises testicular temperature above the 2-2.5 °C-lower level that spermatogenesis needs; cooling habits help.

Memory hook: Sperms are made in the cool shed outside the house.

Tricks to remember Male and Female Reproductive Systems

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

Rete Very Easily Visits Each Urethra
Rete testis, Vasa efferentia, Epididymis, Vas deferens, Ejaculatory duct, Urethra.
Use it when: Tracing the path of sperm.
Sertoli serves, Leydig levels
Sertoli cells serve food to germ cells; Leydig cells level up hormones (androgens).
Use it when: Functions of the two non-germ cells of the testis.
I Am In: infundibulum, ampulla, isthmus
From the ovary end inwards: I-A-I.
Use it when: Parts of the oviduct in order.

Male and Female Reproductive Systems: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Cells of the testis · 3 marks · Short answerBoard level

Name the two kinds of cells lining a seminiferous tubule and the cells found in the interstitial spaces. Give the function of each.

Try it first, then show the solutionSolution

Spermatogonia (male germ cells): divide and undergo meiosis to form sperms (1 mark).
Sertoli cells: provide nutrition to the developing germ cells (1 mark).
Leydig (interstitial) cells: synthesise and secrete androgens such as testosterone (1 mark).

Answer: Spermatogonia (sperm formation), Sertoli cells (nourishment), Leydig cells (androgens).

Example 2: Uterine wall · 2 marks · Short answerBoard level

Name the three layers of the uterine wall and state which layer (a) contracts strongly during childbirth, (b) changes cyclically every month.

Try it first, then show the solutionSolution

Perimetrium (outer), myometrium (middle, smooth muscle), endometrium (inner, glandular) (1 mark).
(a) Myometrium; (b) endometrium (1 mark).

Answer: Perimetrium, myometrium, endometrium; (a) myometrium (b) endometrium.

Example 3: A blocked duct · 3 marks · Short answerHarder board level

Suppose both vasa deferentia of a man are blocked by an infection. (a) Will he still produce sperms? (b) Will his ejaculate contain sperms? (c) Will his secondary sexual characters be affected? Give a reason for each.

Try it first, then show the solutionSolution

(a) Yes: sperms are made in the seminiferous tubules, which are not affected (1 mark).
(b) No: the vas deferens carries sperms from the epididymis to the ejaculatory duct; the semen will contain only seminal plasma from the glands beyond the block (1 mark).
(c) No: androgens from Leydig cells pass into the blood, not through the vas deferens (1 mark).

Answer: Sperms are made but cannot reach the ejaculate; hormones and secondary sexual characters are unaffected.

Example 4: Accessory glands · 3 marks · Short answerHarder board level

Name the male accessory glands and state the role of their secretions. Why are the secretions of the epididymis and accessory glands essential even though they do not make sperms?

Try it first, then show the solutionSolution

Paired seminal vesicles, a single prostate and paired bulbourethral glands (1 mark).
Their secretions form seminal plasma, rich in fructose, calcium and enzymes; bulbourethral secretion also lubricates the penis (1 mark).
Sperms released from the testis still have to mature and gain motility; the fluids of the epididymis, vas deferens, seminal vesicles and prostate make this possible, and only mature, motile sperms can fertilise (1 mark).

Answer: Seminal vesicles, prostate, bulbourethral glands; seminal plasma provides fructose, calcium and enzymes and supports sperm maturation and motility.

Example 5: Reading the ovary · 3 marks · Short answerHarder board level

In a T.S. of ovary a student sees: (P) a follicle with a fluid-filled cavity and two theca layers; (Q) a large yellowish glandular body; (R) a whitish scar-like body. Identify P, Q and R and state the hormone, if any, secreted in large amounts by Q.

Try it first, then show the solutionSolution

P: tertiary follicle (antrum with theca interna and externa) maturing towards a Graafian follicle (1 mark).
Q: corpus luteum, formed from the remains of the Graafian follicle after ovulation; secretes large amounts of progesterone (1 mark).
R: corpus albicans, the degenerated corpus luteum when there is no pregnancy (1 mark).

Answer: P tertiary/Graafian follicle; Q corpus luteum (progesterone); R corpus albicans.

Example 6: Undescended testes · 3 marks · Short answerHOTS / competency

Suppose in a boy the testes fail to descend and remain in the abdominal cavity into adult life. Predict, with reasons, the effect on (a) sperm production, (b) testosterone-dependent features. Suggest why doctors correct the condition early.

Try it first, then show the solutionSolution

(a) Sperm production is reduced or absent: spermatogenesis needs a temperature about 2-2.5 °C lower than internal body temperature, which only the scrotum provides (1 mark).
(b) Leydig cells may still secrete androgens into the blood, so male secondary sexual characters can still develop; it is sperm formation that depends most on the cooler scrotal temperature (1 mark).
Early correction moves the testes into the scrotum before the germ cells are damaged, so fertility can be preserved (1 mark).

Answer: Sperm formation fails at body temperature; androgens may still be made; early surgery protects fertility.

Where students lose marks in Male and Female Reproductive Systems

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

Mistake: Drawing the wrong section
In 2025 examiners reported L.S. of testis, T.S. of ovary or a sperm drawn for the T.S. of testis; in 2024 an L.S. of a plant ovule or only a Graafian follicle for the T.S. of ovary.
Do this: Read the question twice: T.S. of testis shows seminiferous tubules and interstitial cells; T.S. of ovary shows the whole ovary with follicles at several stages, corpus luteum and corpus albicans.
Usually costs: Up to 3 marks.
Mistake: Label lines crossing or overlapping parts
Examiners (2025) noted unclear labels with lines overlapping parts of the diagram.
Do this: Draw label lines with a ruler, parallel where possible, ending exactly on the part; write labels on one side.
Usually costs: ½ mark per unclear label.
Mistake: Mixing up Sertoli and Leydig cells
Both lie in the testis and both are 'helpers'.
Wrong working
Sertoli cells secrete testosterone.
Right working
Leydig cells (interstitial) secrete androgens; Sertoli cells (inside tubules) nourish germ cells.
Do this: Inside the tubule: Sertoli. Outside, between tubules: Leydig.
Usually costs: 1 mark.
Mistake: Missing a duct in the path of sperm
Students jump from testis to vas deferens.
Do this: Write all six: rete testis, vasa efferentia, epididymis, vas deferens, ejaculatory duct, urethra.
Usually costs: 1 mark.

Exam tips

Practise the two ISC diagrams, T.S. of testis and T.S. of ovary, until you can draw each in five minutes with six labels.
Give numbers where NCERT does: 2-2.5 °C, about 250 lobules, 1-3 tubules, 10-12 cm oviduct, 15-20 mammary lobes.
Write 'ampullary region' as the site of fertilisation.
Separate primary sex organs from accessory ducts and glands in classification questions.
Answer 'what if' questions by naming the function that is lost, then the consequence.

Practice questions on Male and Female Reproductive Systems

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

Q1 · 1 mark · MCQBoard level
The part of the oviduct that collects the ovum after ovulation is the:
(a) isthmus (b) ampulla (c) infundibulum with fimbriae (d) cervix
Hint
Finger-like projections.
Answer
(c) Infundibulum with fimbriae.
Q2 · 2 marks · Short answerBoard level
What is the scrotum, and why is it important?
Hint
Temperature.
Answer
The scrotum is the pouch outside the abdominal cavity that holds the testes. It keeps them about 2-2.5 °C below internal body temperature, which is necessary for spermatogenesis.
Q3 · 2 marks · Short answerHarder board level
Trace the path of milk from where it is secreted to the nipple.
Hint
Six structures.
Answer
Alveoli (cells secrete milk into their lumen) → mammary tubules → mammary duct → mammary ampulla → lactiferous duct → nipple.
Q4 · 1 mark · Assertion-reasonHarder board level
Assertion (A): The presence or absence of an intact hymen is a reliable sign of whether a woman has had sexual intercourse.
Reason (R): The hymen can be torn by a fall, sports such as cycling, or a tampon, and may persist after coitus.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
R contradicts A.
Answer
(d). Because the hymen can tear in other ways or persist after coitus, it is not a reliable indicator.
Q5 · 3 marks · Short answerHarder board level
Draw a neat, labelled diagram of the T.S. of a seminiferous tubule with the surrounding interstitial tissue, showing at least six labels.
Hint
Germ cells in order from basement membrane to lumen.
Answer
Labels: basement membrane, spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa in the lumen, Sertoli cell, interstitial (Leydig) cells, blood vessel (any six, correctly placed).
Q6 · 2 marks · Short answerHarder board level
Distinguish between the cortex and medulla of the ovary, and between the corpus luteum and corpus albicans.
Hint
Location; active or degenerate.
Answer
Cortex: peripheral zone of the stroma containing follicles at different stages; medulla: inner zone with blood vessels and connective tissue. Corpus luteum: active glandular body formed from the ruptured Graafian follicle, secreting progesterone; corpus albicans: whitish scar left when the corpus luteum degenerates in the absence of pregnancy.
Q7 · 3 marks · Short answerHOTS / competency
Suppose a woman has had both fallopian tubes removed because of disease, but her ovaries and uterus are normal. (a) Will she ovulate and menstruate? (b) Can she conceive naturally? (c) Which assisted technique could help her, and why? Explain each.
Hint
Where does fertilisation normally occur?
Answer
(a) Yes: ovulation and the menstrual cycle depend on the ovaries, pituitary and uterus, which are intact. (b) No: the ovum cannot be collected and fertilisation, which normally occurs in the ampullary region of the oviduct, cannot take place. (c) In vitro fertilisation: ova are collected from the ovary, fertilised in the laboratory and the embryo transferred into the uterus, bypassing the oviducts.
Q8 · 3 marks · Case-basedHOTS / competency
Read and answer.
Suppose a model of the male reproductive system in a school lab is missing labels. A student finds: (X) a coiled tube along the back of each testis; (Y) a single gland around the urethra just below the bladder; (Z) a pair of small glands below it whose secretion lubricates the penis.
(a) Identify X, Y and Z. (1½)
(b) State one function of X. (½)
(c) Which hormone maintains the functions of these accessory structures, and which cells make it? (1)
Hint
Epididymis, prostate, bulbourethral glands.
Answer
(a) X epididymis; Y prostate; Z bulbourethral (Cowper's) glands. (b) Epididymis stores sperms and its secretion helps their maturation and motility. (c) Androgens (testosterone), secreted by the Leydig (interstitial) cells of the testis.

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.How many testicular lobules does a testis have?Show answer
About 250.
2.Where do the vasa efferentia open?Show answer
Into the epididymis.
3.Which cells of the testis secrete androgens?Show answer
Leydig (interstitial) cells.
4.What forms the birth canal?Show answer
The cervical canal and the vagina.
5.What are the zones of the ovarian stroma?Show answer
Peripheral cortex and inner medulla.
6.What is seminal plasma rich in?Show answer
Fructose, calcium and certain enzymes.

Male and Female Reproductive Systems: frequently asked questions

Why are the testes outside the abdomen?

In the scrotum they stay about 2-2.5 °C cooler than internal body temperature, which spermatogenesis requires.

What is the difference between Sertoli and Leydig cells?

Sertoli cells line the seminiferous tubules and nourish germ cells; Leydig cells lie in the interstitial spaces and secrete androgens.

Where does fertilisation take place in humans?

In the ampullary region of the fallopian tube.

What labels are expected in a T.S. of mammalian ovary?

Germinal epithelium, cortex, medulla, primary and secondary follicles, Graafian follicle (antrum, theca, oocyte), corpus luteum and corpus albicans; any five correctly placed.

What are the male accessory glands?

Paired seminal vesicles, a single prostate and paired bulbourethral (Cowper's) glands.