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The primordial germ cells divide by mitotic division to increase in number and mature as spermatogonium which divides to form primary spermatocytes. The primary spermatocytes divide meiotically to form secondary spermatids which furr divide to from spermatids which mature to form sperms.
Seminal vesicles: They are located near ampullae of vasa deferentia. They do not store sperms. They contribute yellowish, slightly alkaline, viscous seminal fluid that contains sugar fructose, a coagulating enzyme, ascorbic acid and hormone like prostaglandins.
When an egg is not fertilized by sperm in a woman's body process of menstruation takes place where upper soft layers of uterus which are formed to hold fertilized egg is shed outside body along with unfertilized egg if fertilization does not take place.
Ovulation is process when a mature egg is released from ovary. Then egg is pushed down Fallopian tube and is available to be fertilized. In females, ovulation continues after age of 45-50 after which eggs are not released from ovary and re is menopause. Thus, correct answer is option (A), '45-50'.
Vas deferens joins epididymis to seminal vesicle and carries sperm from testes to seminal vesicles. Seminal vesicle contains seminal fluid which helps sperm to move in forward direction.
When male vasa deferentia are blocked, it prevents sperm from entering into seminal glands or ejaculate (semen). No sperms in semen means no fertilization with egg. This process of blocking vas deferens is a means of birth control which is called vasectomy. Thus, correct answer is option A.
Menarche is onset of menstrual cycle or first menstrual cycle in female humans. Menopause marks end of menstrual cycle. Fusion of male and female gamete is known as fertilization or syngamy. Therefore, correct answer is option B.
In second cleavage division, one of two blastomeres usually divides a little sooner than second to form two types of cell inner and outer. The outer cell aligns to form trophoblast while inner mass of cell forms developing embryo. The cavity formed is known as a blastocoel and developed embryo is known as blastocyst.