Question

Define ovulation.

Answer 1

Hint: In females, the primary reproductive organ is called ovary. There are two ovaries in an individual present on either side of the uterus. They are small spherical structures, whitish in colour. The major functions of the ovaries are to secrete female hormones, namely oestrogen and progesterone, production of the egg or ovum by a process called oogenesis.

Complete answer:
The ovaries are covered by a thin germinal epithelium and are composed of a cortex and medulla. The cortex is the outer region of the ovary and comprises ovarian follicles. Each follicle is a flat epithelial cell and is surrounded by a layer of cells called granulosa cells. These follicular cells are formed at the time of birth. However, at that time all these follicles are immature. After a female reaches her puberty, only one follicle called the Graafian Follicle matures every month. This follicle is capable of being fertilized by a sperm, if present. Otherwise, it degenerates.
The process of release of a mature egg from one of the ovaries in females is called ovulation.

Additional Information: The process of ovulation occurs as a result of interplay of the female sex hormones – the oestrogen and progesterone. Just before the process of ovulation, oestrogen levels begin to rise. Ovulation occurs as a result of a surge in the level of Luteinizing hormone from the pituitary gland. At the time of release from the ovary, the ovum, surrounded by a layer of granulosa cells separates from the follicle. The fimbriae, located at the end of oviduct picks up the ovum and transfers it to the fallopian tube – where in the presence of a sperm, fertilization takes place and the zygote moves down to the uterus and is implanted in the uterine wall.
In the absence of a sperm, the ovum degenerates.
In response to the process of development of ovum, the uterine wall thickens and gets ready for the process of implantation. If there is no implantation, the uterine endometrium is shed, resulting in menstruation. This process is repeated in a cycle of 28 days and is known as the Menstrual cycle. The major hormones that take part in the cycle are oestrogen and progesterone from the ovaries, Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from the pituitary gland.

Note: Ovaries form ovum which are released by the process of ovulation. The ovum is fertilized if sperms are present otherwise it disintegrates. As a result the uterus sheds its lining. This cyclical event is known as the Menstrual Cycle. The process of ovulation can be suppressed by birth control pills and when women breastfeed their offsprings.