Reproduction — Short Questions

[Diagram showing: Primary spermatocyte (2n) → Meiosis-I → Secondary spermatocytes (1n) → Meiosis-II → Spermatids (1n) → Sperms (1n)]

[Diagram showing: 2n → First polar body (1n) + Second polar body (1n), Primary Oocyte with Meiosis-I and Meiosis-II stages, Secondary oocyte, Egg (1n)]

The formation of male gametes (sperms) is called spermatogenesis. This process occurs in seminiferous tubules of testes.
The formation of female gametes (egg or ovum) is called Oogenesis. It occurs in ovary in a small, fluid-filled sac called follicle of ovary.

After ovulation, (release of egg), fertilization occurs. It takes place in the following ways.
1. Sperms move towards the egg due to the chemical signals released by the egg or surrounding cells.
2. The acrosome, a cap-like structure on the head of the sperm, releases enzymes which digest the egg's outer layers, allowing the sperm to reach the egg cell membrane.
3. The sperm and egg cell membranes fuse. This fusion triggers reactions in egg. So, the egg's outer layers become impermeable for more sperms.
4. After fusion of membranes, the sperm nucleus enters the egg.
5. Both nuclei fuse to form a diploid zygote.

Spermatogenesis | Oogenesis
i. The formation of male gametes (sperms) is called spermatogenesis. | i. The formation of female gametes (egg or ovum) is called Oogenesis.
ii. This process occurs in seminiferous tubules of testes. | ii. It occurs in ovary in a small, fluid-filled sac called follicle of ovary.
iii. Four haploid sperms are produced. | iii. In meiosis-II secondary oocyte produces two haploid cells i.e. a second polar body and an egg.

The HIV spreads mainly through unprotected sexual contact, sharing of contaminated needles, transfusion of infected blood and from an infected mother to her child during childbirth or breast feeding.

i. Oestrogen and progesterone
Oestrogen | Progesterone
• It is a hormone primarily produced by the ovaries of female. | • It is a hormone produced by the ovaries after ovulation and also during pregnancy.
Functions | Functions
• It initiates and regulates the development of female secondary sexual characteristics during puberty, such as breast development, widening of the hips, and the onset of menstrual cycles. | • It prepares the uterus walls for implantation of fertilized egg. It maintains pregnancy by preventing contractions of the uterus.
• It also regulates the female reproductive cycle. |

ii. Spermatogenesis and oogenesis
Spermatogenesis | Oogenesis
i. The formation of male gametes (sperms) is called spermatogenesis. | i. The formation of female gametes (egg or ovum) is called Oogenesis.
ii. This process occurs in seminiferous tubules of testes. | ii. It occurs in ovary in a small, fluid-filled sac called follicle of ovary.
iii. Four haploid sperms are produced. | iii. In meiosis-II secondary oocyte produces two haploid cells i.e. a second polar body and an egg.

iii. Spermatocyte and oocyte
Spermatocyte | Oocyte
In seminiferous tubules, the diploid gamete mother cells called primary spermatocytes are merest which after | In follicle, there is a diploid gamete mother cell called primary oocyte.

It is essential for the survival and continuation of a species, but it is not crucial for survival of an individual.

In males, the process of sperms production is called spermatogenesis, where sperm cells are produced in the testes.

Spermatogenesis is a continuous event that starts from puberty and remains continue throughout the life simultanously in both testes

Fertilization in rabbits occurs internally after mating. During mating, the male rabbit deposit sperm into the female rabbit's vagina. The sperm swim from vagina through the cervix and into the uterus.
From the uterus they move into the fallopian tubes. Female rabbits are induced ovulators meaning that ovulation happen after mating due to stimulation. The eggs are released from ovaries into the fallopian tubes. In the fallopian tubes, sperm meets the egg (or eggs) and fertilizes an egg to form a zygote.

Testosterone promotes the development of male secondary sexual characteristics, such as
• The growth of facial hair
• Deepening of the voice
• Increased muscle mass

Both testosterone and FSH are necessary for normal spermatogenesis, but they act at different points in the process.
Testosterone promotes the final maturation of sperm and maintenance of the reproductive environment, while FSH initiates and regulates the early stages of sperm production.

Oestrogen is responsible for the development of female reproductive organs, such as the uterus, fallopian tubes and secondary sexual characteristics during puberty.

Ovulation, (the release of an egg from the ovary), is triggered by a surge in luteinizing hormone (LH). This LH surge is initiated by rising levels of oestrogen which reach a peak just before ovulation.

Progesterone is produced by corpus luteum in the ovary. It plays an important role in preparing the body for pregnancy by thickening the uterine lining, which is essential for embryo implantation. High concentration of progesterone also inhibits the release of FSH.

The eggs are released from the ovaries into the fallopian tubes. In the fallopian tubes, sperm meets the egg (or eggs) that have been released from the ovaries. One sperm penetrates and fertilizes an egg, combining genetic material from both parents to form a zygote.

A storage area for sperms on the upper part of the testes is called Epididymis.

A part of the female reproductive system receives egg cell discharged from the ovary and fertilization happens in the fallopian tube.

A structure in the ovary in which the mature egg develops. Follicles are stimulated by FSH.

An accessory gland (Cowper's gland) in rabbit's male reproductive system which provide lubrication to the ducts.
An accessory gland (prostate gland) in the male reproductive system, produces a secretion that neutralizes the acidity of the fluid part of semen.

The associated gland in male reproductive system produces secretions having nutrients for the sperms.

These are masses of coiled tubes present in testes and sperms are formed in these tubules.

The tube that carry sperms from each testis to the urethra.

These diseases can be caused by bacteria, viruses, or parasites.

i. STDs often affect the genital, urinary, and reproductive organs. Common STDs include HIV/AIDS, syphilis, herpes etc. Many STDs can be asymptomatic, meaning individuals may carry and spread the infection without showing signs.
ii. If STDs are left untreated, they can lead to serious health complications such as infertility, organ damage, and other infections.

Only one large, viable egg (ovum) is produced from primary oocyte because oogenesis involves unequal cell division (cytokinesis), concentrating all necessary cytoplasm, nutrients and organelles into one cell to support early embryonic development, while the other cells (polar bodies) receive minimum cytoplasm and degenerate.

A sperm cell's structure is perfectly adapted for fertilization. Its streamlined head carries DNA and an enzyme filled acrosome to penetrate the egg, a packed mid-piece contains mitochondria for energy and a powerful tail (flagellum) provides the whip like motion needed to propel it through the female reproductive tract to reach the egg.

To prevent HIV transmission individuals should avoid sharing needles, take ART (antiretroviral therapy) U = U (undetectable equals untransmutable) to prevent transmission, get tested regularly and know your status and avoid sharing razors, toothbrushes or anything with blood.