What is embryogenesis? Mention two important events that occur during embryogenesis.

The formation of an embryo from the single-celled zygote after fertilisation is called embryogenesis. It is defined by the sequential changes that include the cleavage of zygote, growth and differentiation of the germ layers into different parts of the body. The two most important events that occur during embryogenesis are, the zygote undergoes mitotic divisions with no significant growth (a process known as cleavage) and cellular differentiation, leading to development of a multicellular embryo.

Name the layer of the uterus that exhibits strong contractions during parturition.

The uterus consists of the following three tissue layers, i.e., endometrium (inner layer), myometrium (middle layer) and perimetrium (outer layer). Myometrium is the layer of the uterus that exhibits strong contractions during parturition.

Draw a neat labelled, diagrammatic sectional view of female reproductive system

The human female reproductive system is made up of primary sex organs and accessory sex organs. It includes the ovaries, Fallopian tubes, uterus, vagina, accessory glands, and external genital organs. The ovaries are the primary sex organs. Fallopian tubes are two small tubes and also called oviducts. These tubes present near both the kidneys and remain to transport the zygote to the uterus. The vagina connects with the cervix (meaning neck) to the uterus, or womb. The uterus is shaped like an upside-down pear, with a dense lining and muscular walls. The uterus also includes some of the female body's strongest muscles. The Fallopian tubes connect the uterus to the upper uterine corners of the ovaries.

What are homogametes and heterogametes?

Gametes can be characterised as the reproductive cell of the organisms. Homogametes can be best defined as those gametes which bear morphological and anatomical similarities with each other. Heterogametes can be characterised as those gametes which are different from each other. The male gamete in humans is known as the sperm while the female gamete is known as the ovum or the egg. This sperm fertilizes the ovum to form a zygote which further develops into an embryo.

What is Foetal Ejection Reflex?

Foetal ejection reflex can be characterised as neuroendocrine reflex comprising the self-sustaining cycle of uterine contractions initiated by the pressure at the cervix or vaginal walls. Foetal ejection reflex can be best defined as a positive feedback mechanism. Increased pressure on the internal walls of the cervix stimulates the release of contractile protein or hormone. The hormone oxytocin causes uterine contractions which in turn increases the pressure on the cervix until the delivery of the baby.

What is implantation?

Fertilisation is a process involved in sexual reproduction in which male and female gametes fuse to form the zygote. After fertilization, zygote passes into the uterus. By means of repeated cell division, the zygote forms the embryo. The embryo then becomes embedded in the lining of the wall of the uterus. This is called implantation.