Human Reproduction Test 10

- At the end of meiosis I females have two daughter cells and meiosis II only occurs if and when the fertilization occurs by the sperm cell.
- Meiosis II starts after the sperm proceeds fertilization process in female 

• During birth, prostaglandins initiate the contraction in smooth muscles of uterine wall which causes labor pains.
• The pressure of fetus’s head against the cervix and send signals to make hypothalamus to trigger the release of oxytocin from the posterior pituitary. Together, oxytocin (OT) and prostaglandins stimulate strong uterine muscle contraction forcing the fetus downwards and thereby expelling it out of the uterus. Thus, to hasten the childbirth, it is advisable to administer the hormone that stimulates uterine smooth muscle contraction i.e. oxytocin. This makes option A correct.

Pattern of embryonic cleavage is determined both by the position of the mitotic spindles and by the amount and distribution of yolk. Yolk tends to inhibit cleavage. It slows it down or actually prevents complete cleavage. The yolk is an adaptation of those animals that go through more or less of embryogenesis isolated from any food supply.

The key male reproductive organs include the testes, epididymis, urethra, vas deferens, prostate gland, seminal vesicle, and penis. The ejaculation process begins as the penis fills with blood and becomes erect. With sufficient stimulation, mature sperm travels from the epididymis through the vas deferens, a muscular tube, which propels sperm forward through smooth muscle contractions. From the ampulla, seminal fluid is propelled forward through the ejaculatory ducts toward the urethra, passing first by the prostate gland, where a milky fluid is added to form semen.

FSH is responsible for the initiation of spermatogenesis and sperm differentiation. It binds with Sertoli cells and spermatogonia and induces proliferation of spermatogonia .

So, the correct answer is 'FSH'.

The male accessory glands include paired seminal vesicles. The seminal vesicles are narrow, long pouches with muscular tissue in their wall, lying between the urinary bladder and rectum. Sugar fructose is present in the secretion of the seminal vesicle. Fructose is an energy source used by sperm. This fluid is known as semen. Sixty per cent of semen is produced by seminal vesicles.

Primary oocyte undergoes first meiotic division to produce one secondary oocyte (egg cell) and first polar body (nonfunctional cell). Secondary oocytes complete meiosis II and produce one functional ovum and a second polar body. First and second polar bodies are nonfunctional cells; so, oogenesis produces one functional egg cell in each round. Thus, the correct answer is A.

• One primary oocyte will form one secondary oocyte and one polar body. One secondary oocyte will further form one ovum and one polar body and 1st polar body will produce two more polar bodies.
• So 1 primary oocyte will eventually form one ovum. So, 100 primary oocytes will form 100 eggs.

Oxytocin is a hormone that acts on organs in the body and as a chemical messenger in the brain, controlling key aspects of the reproductive system, including childbirth and lactation, and aspects of human behaviour. Oxytocin is produced in the hypothalamus and is secreted into the bloodstream by the posterior pituitary gland. The posterior pituitary does not produce any hormones of its own, rather, it stores and secretes two hormones made in the hypothalamus— oxytocin and antidiuretic hormone. Oxytocin stimulates the uterine muscles to contract and also increases the production of prostaglandins, which increase the contractions further.

After fertilization, the zygote undergoes cleavage and divisions, thereby forming the blastocyst, which gets implanted in the endometrium of the uterus. The blastocyst then divides further and develops inside the uterus only. The uterus is the womb and is a major female reproductive hormone. Thus, the correct answer is option b.

Corpus luteum is the structure which is formed by the follicles after the egg is released from the Graafian follicle. This is a yellow coloured structure which is present in the ovary. The corpus luteum is the structure which is responsible for the release of the hormone progesterone. This is known as the pregnancy hormone which causes changes in the ovary and increasing the cell lining in the uterus. The hormone helps in maintaining pregnancy. 

The Bartholin's gland is the small glands which are located on the lateral and posterior sides of the vaginal opening. These glands are responsible for the secretion of the mucus which helps in the lubrication of the vaginal tract. The gland is considered as similar to the bulbourethral glands in males.

The follicular phase of the female menstrual cycle includes the maturation of ovarian follicles to prepare one of them for release during ovulation. During the same period, there are concurrent changes in the endometrium, which is why the follicular phase is also known as the proliferative phase.

The lower portion of the uterus forms a narrow structure which forms the cervix. The cervix extends to form the birth canal through which the fetus comes out during parturition. The vagina forms the opening of the birth canal. These two structures together are referred to as the birth canal or passage.

• The menstrual cycle is a monthly cycle in which the primate females ovulate once in a month.
• Menstruation is important because it prepares the body for the fertilization and is a key process in reproduction.
• The cycle occurs in humans, chimpanzees and Orangutans, gorillas and monkeys.
• Other mammals have a similar cycle which is known as the oestrous cycle.