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23

Female reproductive organs and associated functions are given below in column I and II. Fill the blank blanks.

Column I Column II
Ovaries Ovulation
Oviduct $A$
$B$ Pregnancy
Vagina Birth
Explanation
Column I Column II
Ovaries Ovulation
Oviduct Fertilisation
Uterus Pregnancy
Vagina Birth

The female reproductive system consists of a pair of ovaries, a pair of Fallopian tubes (oviducts), uterus, vagina, external genitalia and mammary glands.

The ovaries have both an exocrine function (production of ova) and an endocrine function (secretion) of female sex hormones.

The oviduct (Fallopian tube) conveys the egg from the ovary to the uterus, and also provides the appropriate environment for its fertilisation. The uterus (womb) is a large, inverted, pear-shaped, elastic sac specialised for the development of the embryo.

The vagina is adapted for receiving the penis during copulation, allowing menstrual flow and serving as the birth canal during parturition

24

From where the parturition signals arise-mother or foetus? Mention the main hormone involved in parturition.

Explanation

Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex.

The hormone involved in parturition is oxytocin that acts on the uterine muscle and causes stronger uterine contractions. This leads to the expulsion of the baby out of the uterus through the birth canal.

25

What is the significance of epididymis in male fertility?

Explanation

The epididymis helps the sperm in attaining maturity, acquiring increased motility and fertilising capacity. It also stores sperms for a short period before entering the vasa deferens. The epididymis shows peristatic and segmenting contractions at intervals to push the sperm away from the testis.

26

Give the names and functions of the hormones involved in the process of spermatogenesis. Write the names of the endocrine glands from where they are released.

Explanation

$$ \text { Hormones involved in spermatogenesis are } $$

Hormone Function Gland
Gonadotrophin releasing hormone (GnRH) Acts on pituitary to secrete LH and FSH. Hypothalamus
Luteinizing Hormone (LH) Acts on Leydig cells and stimulates synthesis and secretion of androgens Pituitary
Androgens Stimulate process of spermatogenesis Testis
Follicle Stimulating Hormone (FSH) Acts ons sertoli cell and stimulates secretion of some factors that help in process of spermiogenesis Pituitary
27

The mother germ cells are transformed into a mature follicle through series of steps. Provide the missing steps in the blank boxes.

Explanation
The germinal epithelial cells divide repeatedly until many diploid oogonia are formed. The oogonia grow to form primary oocytes. Each primary oocyte then gets surrounded by a layer of granulosa cells and then called the primary follicle. The primary follicles get surrounded by more layers of granulosa cells and called secondary follicles. The secondary follicle soon transforms into a tertiary follicle which is characterised by a fluid filled cavity called antrum. The primary oocyte within the tertiary follicle undergoes meiotic division to become a secondary oocyte and a first polar body (haploid). The tertiary follicle further changes into the mature follicle or Graafian follicle. The Graafian follicle now ruptures to release the secondary oocyte (ovum) from the ovary by the process called ovulation.