Question

(a) Draw a diagrammatic sectional view of the female reproductive system of human and label the parts
(i) where the secondary oocytes develop
(ii) which helps in collection of ovum after ovulation
(iii) where fertilization occurs
(iv) where implantation of embryo occurs.
(b) Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females.

Answer 1

A)

i)

1) The secondary oocyte develop in the ovary after the onset of puberty in females.

2) The secondary follicle becomes larger turning into a Graafian Follicle, just before ovulation.

3) The formation of secondary oocyte begins at the Meiosis 2 but stops in the middle phase known as metaphase.

4) The Graafian follicle or the mature follics ruptures and releases its secondary oocyte and the process is known as ovulation.

ii)

1) The collection of Ovum after Ovulation is processed by expelling the secondary oocytes which are surrounded by few granulosa cells into the peritoneal cavity.

2) High concentration of estrogen that occur around the tome of the ovulation induce contractions of the smooth muscles of the uterine tube.

3) These contractions occur at a time interval of evey 5-10 seconds.

4) The movement current of the uterus is generated by the beating of the cilia that lines the outer portion of the uterine tube.

5) The beating of the cilia is stimulated and accelerated by the presence of the hormone estrogen.

iii)

1) The site of fertilization of the egg and the sperm is the ampulla-isthumus junction of the fallopian tube.

2) The egg is not stable and is in a moving condition because of the muscular contractions and the beating of the cilia until the sperm reaches the fallopian tube travelling along the uterus.

3) The fertilization at the ampullary-isthemic junction can occur only when the ovum and the sperm are transported simultaneously to the junction.

B)

The role of Pituitary Gland and the hypothalamus in menstrual cycle of the femals is :

1) Hypothalamus is the gland which helps to intitiate the start of the menstruation in the femals by releasing GONADOTROPIN RELEASING HORMONE.(GnRH)

2) Gonadotropin releasing hormone stimulates the pituitary gland to secrete LUTEINIZING HORMONE ( LH) AND FOLLICULAR STIMULATING HORMONE (FSH).

3) Pituitary Gland translates the secreation produces by the hypothalamus into a signal that can be conducted and understood by the ovarian follicle.

4) LH in the ovarian follicle stimulates the theca cells to secrete ANDROSTENEDIONE.

5) LH stimualtes granulosa cells to secrete ACROMATASE.

6) Acromatase stimulates the conversion of androstenedione to estradiol (a type of estrogen) in presence of FOLLICULAR STIMULATING HORMONE.

7) A critical concentration of estradiol produced causes positive feedback in hypothalamus to GnRH and LH (LHsurge)

8) LH SURGE initiates the process of ovulation .

9) After the ovulation the follicle is transformed into corpus luteum.

10) corpus luteum is stimulated by LH or chorionic gonadotropin hormone to produce progesterone.

11) Progesterone stimulates and prepares the endometrium for inplantation by thickening the walls of the endometrium.

12) If there is no implantation for a period of time, the endometrium lining starts shedding and continues for 4-5days.