Describe the structure of a seminiferous tubule.
Solution and Explanation
The production of sperms in the testes takes place in a highly coiled structure called the seminiferous tubules. These tubules are located in the testicular lobules. Each seminiferous tubule is lined by germinal epithelium. It is lined on its inner side by two types of cells namely spermatogonia and sertoli cells respectively. Spermatogonia are male germ cells which produce primary spermatocytes by meiotic divisions. Primary spermatocytes undergo further meiotic division to form secondary spermatocytes and finally, spermatids. Spermatids later metamorphoses into male gametes called spermatozoa. Sertoli cells are known as nurse cells of the testes as they provide nourishment to the germ cells. There are large polygonal cells known as interstitial cells or leydig cells just adjacent to seminiferous tubules. These cells secrete the male hormone called testosterone.
Top Questions on Human Reproduction
Arrange the following events in the correct order pertaining to fertilization in the human reproductive system.
(A) The blastocyst becomes embedded in the endometrium.
(B) Finger-like projections appear on the trophoblast called chorionic villi.
(C) The blastomeres are arranged into trophoblast and the inner cell mass.
(D) The zygote divides mitotically and transforms into an embryo with 8-16 blastomeres, called a morula.
- CUET (UG) - 2025
- Biology
- Human Reproduction
Study the graphs given below for Case 1 and Case 2 showing different levels of certain hormones and answer the question that follows:
(a) Which hormone is responsible for the peak observed in Case 1 and Case 2? Write one function of that hormone.
(b) Write changes that take place in the ovary and uterus during follicular phase.
Student to attempt either sub-part (c) or (d):
(c) Name the hormone Q of Case 2. Write one function of hormone Q.
OR
(d) Which structure in the ovary will remain functional in Case 2? How is it formed?- CBSE CLASS XII - 2025
- Biology
- Human Reproduction
- Shyam and Radha are expecting their first child with Radha being in her second month of pregnancy with no complications. Shyam’s family has a history of cystic fibrosis while Radha’s family has a history of Down’s syndrome, leading to a concern that the baby may have one of these conditions.
(a) Suggest and explain a way of testing if their baby is at risk for any genetic disorders.
(b) In case of presence of one or both of the abnormalities and posing a risk to the mother’s health, mention one possible option for them to consider. Is that option safe for Radha at the current gestational age? Justify.
(c) Under what conditions is the process mentioned in (b) illegal?- CBSE CLASS XII - 2025
- Biology
- Human Reproduction
- Assertion (A): Saheli is the World’s first non-steroidal oral contraceptive pill.
Reason (R): It has been developed by National Institute of Immunology, New Delhi.- CBSE CLASS XII - 2025
- Biology
- Human Reproduction
Match the following items of Column-I with that of Column-II:
- CBSE CLASS XII - 2025
- Biology
- Human Reproduction
Questions Asked in CBSE CLASS XII exam
- Analyse the role of Gandhiji after independence of India.
- CBSE CLASS XII - 2025
- Mahatma Gandhi and the Nationalist Movement
A current-carrying coil is placed in an external uniform magnetic field. The coil is free to turn in the magnetic field. What is the net force acting on the coil? Obtain the orientation of the coil in stable equilibrium. Show that in this orientation the flux of the total field (field produced by the loop + external field) through the coil is maximum.
- CBSE CLASS XII - 2025
- Magnetism and matter
- Sudha, Sudama and Sulochna were partners in a firm sharing profits equally. On 31st March, 2020, Sudha retired. On the date of retirement ₹ 2,40,000 became due to her. Sudama and Sulochana agreed to pay Sudha in four equal yearly instalments plus interest @ 10% p.a. on the unpaid balance starting from 31st March, 2021. The firm closes its books on 31st March every year.
Prepare Sudha’s loan account till it is fully paid.- CBSE CLASS XII - 2025
- Retirement and Death of a Partner
- Using integration, find the area of the region bounded by the line \[ y = 5x + 2, \] the \( x \)-axis, and the ordinates \( x = -2 \) and \( x = 2 \).
- CBSE CLASS XII - 2025
- Evaluation of Definite Integrals by Substitution
- Centurian Ltd. invited applications for issuing 2,00,000 equity shares of ₹ 10 each at a premium of ₹ 20 per share. The amount was payable as follows: On Application and Allotment – ₹ 20 per share (including premium ₹ 17 per share)
On First and Final call – ₹ 10 per share (including premium ₹ 3 per share)
Applications were received for 3,00,000 equity shares and allotment was made to the applicants as follows: (i) Applicants for 2,00,000 shares were allotted 1,50,000 shares.
(ii) Applicants for 1,00,000 shares were allotted 50,000 shares.
Excess money received on application and allotment was adjusted towards sums due on first and final call. Deepali, who had applied for 2,000 shares, failed to pay the first and final call money. Her shares were subsequently forfeited. Deepali belonged to Category (i).
Pass necessary journal entries for the above transactions in the Books of Centurian Ltd.
Open Calls-in-Arrears and Calls-in-Advance account, wherever necessary.- CBSE CLASS XII - 2025
- Accounting for Share Capital
Concepts Used:
Male Reproductive System
The male reproductive system contains the external genitals (the penis, testes and the scrotum) and internal parts, including the prostate gland, vas deferens, and urethra. A man's fertility and sexual traits depend on the normal functioning of the male reproductive system, as well as hormones released from the brain.
Read More: Human Reproductive System
Organs and functions:
The male reproductive system is responsible for reproduction. It is made of the following parts:
Penis — the organ used for urination and sexual intercourse. It has spongy tissue which can fill with blood to cause an erection. It contains the urethra, which carries both urine and semen.
Scrotum — this is a loose bag of skin that hangs outside the body, behind the penis. It holds the testes in place.
Testes (or testicles) — these are a pair of egg-shaped glands that sit in the scrotum, on the outside of the body. They produce sperm and testosterone, which is the male sex hormone.
Epididymis — this is a highly coiled tube that lies at the back of the testes. All sperm from the testes must pass through the epididymis, where they mature and start to ‘swim’.
Vas deferens — this is a thick-walled tube joined to the epididymis. It carries sperm from the epididymis up to the prostate gland and urethra.
Prostate gland — this is a walnut-sized gland that sits in the middle of the pelvis. The urethra runs through the middle of it. It produces the fluid secretions that support and nourish the sperm.
Urethra — this is a tube that extends from the bladder to the external opening at the end of the penis. The urethra carries both urine and sperm.
Seminal vesicles — these are 2 small glands above the prostate gland that make up much of the fluid in semen.