a) Inner cell mass. It forms the tissues of future embryo
b) Morula
c) In the inner cell mass.
d) The pole of the blastocyst that contains the inner cell mass

Differentiate between proliferative and secretory phases

(i)Test-tube baby program
In this method ova from the wife or a donor female and the sperms from the husband or a donor male are allowed to fuse under simulated conditions in the laboratory.
The zygote or early embryo is implanted into the fallopian tube or uterus for further development.
(ii)Intracytoplasmic sperm injection(ICSI)
In this method the sperm is directly injected into the ovum to form the zygote and then embryo transfer is cerried out.

(a) This method requires from sexual intercourse when conception is mostly likely, i.e., a few days before or a few days after ovulation. This method is not 100% safe because timing of ovulation may vary in women because of physiological complexities. Hence, ovulation may occur earlier or it may be delayed for many days 
(b) Condoms are mechanical barriers which provent spermatozoa to come to ovum so that fertilization dest not occur.
(c) Birth control pills (oral contraceptives) check ovulation by inhibiting the secretion of gonadotropic hormones (FSH and LH) that are necessary for ovulation. Therefore, these are called physiological devices.

a) Structure of ovum. Most animal eggs are spherical or oval, non-motile but on close examination. it is noted that one pole is different from the other. The pole from which polar bodies are given off is called animal pole while the opposite is termed as vegetal pole. Thus it is said to have polarity. Thus various cytoplasmic substances are distributed along the axis in unequal manner. The nucleus also called (germinal vesicle) having chromatin network is surrounded by nuclear membrane. It also contains prominent nucleolus. All animal eggs contain some reserve material to provide food called yolk. The cytoplasm of ovum is called ooplasm. It lacks centrosome but contains cortical granules derived from Golgi bodies in its outer region termed cortex.
(b) Function of Zona pellucida. During fertilisation as a result of cortical reaction, zona pellucida hardens and prevents the entry of additional sperms (polyspermy).

(i) Horne 'X' is Luteinising Hormone (LH) and 'Y' is Follicle Stimulating Hormone (FSH).
(ii) (a) Follicular phase (proliferative phase).
(b) Ovulatory phase (release of ovum) followed by luteal phase.
(c) Luteal phase.
(iii) (a) FSH is secreted by the anterior pituitary, which stimulates the ovarian follicle to secrete oestrogen, which in turn stimulates the proliferation of the endometrium of the uterine wall.
(b) Both LH and FSH attain a peak level in the middle of cycle (about 14th day). Rapid secretion of LH leading to its maximum level during the mid-cycle is called LH surge. It induces rupture of Graafian follicle and thereby the release of ovum (ovulation). Due to these events, this phase is termed as evulatory phase of menstruate cycle.
(c) The remaining cells of ovarian follicles are stimulated by the LH to develop corpos luteum. The corpus luteum secretes large amount of progesterone, which is essential for the maintenance of endometrium. This is known as luteral phase.

(b) Spermatogenesis starts at the age of puberty due to significant increase in the secretion of gonadotrophins releasing hormone. It acts on pituitary gland to bring release of gonadotrophin. Oogenesis is initiated during embryonic development stages.
(c) Spermatogenesis is completed in tests. Oogenesis is completed in the fallopian tube at the time of fertilization.