Tag: fertilization in humans

Ejaculation is the discharge of semen, usually carrying sperms from the male reproductive tract during copulation.
Insemination is the introduction of a sperm into a female for fertilization.
Fertilization is the fusion of male and female gametes.
Parturition is the action of giving birth to young ones.
Thus, the correct answer is option A.

• Zygote is a unicellular structure formed from fusion of male and female gametes.
• Zygote undergoes cell differentiation and cell division (mitosis) to form embryo.
• Embryo is multicellular structure.

The embryo is an unborn or unhatched offspring in the process of development. It results from sexual reproduction, where there is a fusion of male and female gametes.
Thus, the correct answer is the option (B), 'Male and female gametes'.

A zoospore is a motile asexual spore that uses a flagellum for locomotion.
Spores are formed by certain fungi and algae, in response to unfavorable growing conditions.
A gamete is a reproductive cells that unite at fertilization to form a new cell (zygote). This gamete is haploid in nature.
Thus, the correct answer is option C.

Zygote is the fertilized egg, that results from the union of a female gamete (egg or ovum) with a male gamete (sperm) by a process called fertilization.
Placenta is an organ that connects the developing fetus to the uterine wall.
Foetus is the state between the embryonic stage and birth.
The embryo is about five weeks old (or from 7th week of pregnancy).
Thus, the correct answer is option D.

• Gonadotrophin regulating hormone (GnRH) secreted by the hypothalamus stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in male. 
• FSH enters the testes stimulating the Sertoli cells which help to nourish the sperm cells that the testes produce to begin the process of spermatogenesis. Similarly in females, GnRH secreted by the hypothalamus stimulates the release of FSH, which stimulates the growth of egg cells, and LH, which signals for the ovulation of an egg from its follicle. 

• FSH or follicle stimulating hormone is a pituitary hormone.
• It induces oogenesis in females by inducing development of Graafian follicle from the primordial follicle.
• In males, it induces spermatogenesis by inducing primary spermatocytes to undergo the first division of meiosis, to form secondary spermatocytes.

The zygote undergoes series of mitotic divisions to form new cells and the process is known as cleavage. The zygote at the blastocyst stage is implanted into the uterine wall. The contractions of muscles in the uterus during parturition occurs in the presence of oxytocin. The period when the menstrual cycle stops is known as menopause.