Female reproductive structure - class-XI

The method of sterilization is tubectomy (female) or vasectomy (male). While loop, IUD and diaphragm are temporary way to keep time gap between two children.

Bartholin's glands are a part of the female reproductive tract. These are present on either side of the vagina are small in size. These glands secrete mucus to keep the vagina lubricated. These glands are analogous to the bulbourethral glands of the males. So, the correct option is 'On either side of the vagina in humans'.

A. The release of ovum occurs first, followed by fertilization, implantation in the uterus, gestation in which the foetus develops and then childbirth. So, the correct order is Ovulation, Fertilization, Implantation, Gestation, Childbirth

• Estrogen is secreted by follicles on the ovaries and is also secreted by the corpus luteum after the egg has been released from the follicle and from the placenta.
•  Follicle-stimulating hormone (FSH) stimulates the ovarian production of estrogens by the granulosa cells of the ovarian follicles and corpora lutea.
  
• Hence estrogen is secreted by Ovaries.
• So, the correct answer is 'Ovaries'.

Normally, only a single egg is released alternately from one of the two ovaries each month during the menstrual cycle, not one from both simultaneously. Therefore, the statement is false.

In a typical menstruation cycle, 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 called LH surge, induces rupture of Graafian follicle and thereby the release of ovum (ovulation). The ovulation (ovulatory phase) is followed by the luteal phase during, which the remaining parts of the Graafian follicle transform as the corpus luteum. The corpus hemorrhagicum ("bloody body") is a temporary structure formed immediately after ovulation from the ovarian follicle. After the trauma heals, the subsequent structure is called as the corpus luteum (which in turn becomes the corpus albicans before degenerating). The corpus luteum assumes endocrine function and secretes large amounts of progesterone hormone which is essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy.

In most of the higher plants and animals including humans, the male gamete is small and motile, whereas, female gamete is large and immotile. The female gamete contributes both the genetic material as well as cytoplasm during zygote formation as compared to this the male gamete does not contribute cytoplasm but provides only half the genetic complement. Hence, major cell organelles like mitochondria and chloroplasts show cytoplasmic or maternal inheritance pattern. Thus, the correct answer is option C.

The release of an egg from the ovary is called ovulation. This process occurs in the ovulatory phase of the menstrual cycle when the secondary oocytes forms Graafian follicle which then ruptures to release the ovum. The ovulation in human females occurs under the influence of luteinizing hormone LH.

A woman typically ovulates once per month. Over the course of a year, this results in approximately 12 eggs being released.

During early cleavage, the embryo undergoes cell division without increasing in total volume, so the 32-celled stage (morula) is roughly the same size or smaller than the original fertilized egg due to the zona pellucida constraint.

Mature egg secretes a chemical known as fertilizin, which is composed of glycoprotein (monosaccahride and fatty acid substance). Sperm has on its surface a protein substance known as antifertilizin, which is composed of acidic amino acids. The fertilizin and antifertilizin interacts together and this interaction makes the sperms stick to the egg surface. Hence, option B is correct answer.

The average length of the menstrual cycle is about 28 days. By convention the days of the cycle are numbered from the beginning of the menstrual phase of the menstrual cycle, which usually lasts about 4 days. This is followed by the proliferative phase (about 10 days), then by the secretory phase (about 14 days). 

Estrogens are the primary female sex hormones. They promote the development of female accessory/secondary sexual characteristics, such as breasts, and are also involved in the thickening of the endometrium and other aspects of regulating the menstrual cycle.

A cross section of ovary reveals a cortex and a vesicular medulla. The cortex contains round epithelial vesicle or follicles; follicles are actual center of ovum production or oogenesis. Each primary oocyte is surrounded by a layer of granulosa cells and then called the primary follicle. Follicles are usually located directly beneath the cortex of the ovary. They secret estrogen. But once they begin to mature, they migrate towards the inner medulla. The medulla consists of layers of soft stromal tissue. The stromal tissue contains rich supply of blood vessels, nerves and lymph vessels.

In humans, the menstrual cycle starts with the menstrual phase, when menstrual flow occurs and it lasts for 3-5 days. The menstrual flow results due to breakdown of endometrial lining of the uterus and its blood vessels which forms liquid that comes out through vagina. Menstruation only occurs if the released ovum is not fertilised. 

When a woman is born there are usually one million eggs in each ovary and one egg will be released, when she ovulates every month during her menstrual cycle, which is approximately 400-500 eggs over her lifetime. As a woman gets older the rest of the eggs disappear, break down or deteriorate and by the time she reaches menopause, there are no eggs left. Thus, the correct answer is option B.

Progesterone is produced in large amounts in the ovaries by the corpus luteum. It begins producing at the stage of puberty and produced till menopause. It is involved in the menstrual cycle, pregnancy and embryogenesis of humans and other species. 

The luteal phase is marked by the increased concentration of the luteinizing hormone. The LH stimulates the corpus luteum to secrete progesterone which helps in the maintenance of the pregnancy by increasing the thickening of the cell lining of the endometrial wall. 

The gametes are the haploid cells which are produced by the meiotic division. The egg is the female gamete which is produced through oogenesis. The gametes are haploid and contain only one set of the chromosome. So, the egg cell contains the 22 autosomes and one X chromosome. Since the female somatic cell contains two X chromosome, there will be only one X chromosome in the gamete.

After implantation of blastocyst (pregnancy), the placenta produces the hormone hCG (human chorionic gonadotropin) hCG promotes the maintenance of the corpus luteum to secrete the hormone progesterone and estrogen. High levels of hCG stimulates endometrial thickening also.

The sequence is: FSH secretion (A) leads to follicle growth (C), which leads to high estrogen and LH surge (E), causing ovulation (D), followed by the formation of the corpus luteum (B).

The prostate gland in males contributes to seminal fluid. The female equivalent, often cited as having similar embryological or functional roles, is the Skene's gland (paraurethral gland), not Bartholin's or Bulbourethral glands.

Progesterone is secreted by the corpus luteum for maintenance of the endometrial lining. Corpus luteum is formed from the remains of the matured Graafian follicle.

Menstruation occurs when the corpus luteum degenerates, leading to a drop in progesterone. If fertilization occurs, the corpus luteum is maintained by hCG, preventing menstruation.

The female external genitalia contains vulva, Bartholin's gland, and clitoris. Further vulva contains mons pubis, labia majora, and labia minora. Bartholin's gland help in lubrication of vagina and clitoris is a tiny finger-like structure which helps in stimulation.

The external genitalia of human female consists of:

Bartholin's glands are a pair of small glands situated on each side of the vaginal opening in human females. They secrete a thick, viscid secretion for lubrication during copulation.

Oophorocystosis is the disorder of ovaries in which formation of cysts. These are small egg follicles that don't grow to ovulation and are the result of altered hormone levels.

LH, FSH, and Estradiol are key hormones regulating the menstrual cycle. TSH (Thyroid Stimulating Hormone) regulates the thyroid gland and has no direct role in the menstrual cycle.

In human adult female oxytocin is a hormone released by the pituitary gland (neurohypophysis), that causes contraction of the uterine muscles during labour.

After birth, the first milk released by mammary glands is called colostrum. It is released for 2-3 days. It is thin, yellowish fluid containing cells from the alveoli of glandular tissue of mammary glands and is rich in protein, antibodies, but low in fat.

Primary oocyte undergoes meiosis 1 and the first polar body and secondary oocyte are produced. Secondary oocyte which is arrested at metaphase 2 develops into the graffian follicle and after the secretion of the LH hormone occurs which leads to ovulation.

If the ovum fails to get fertilised, then corpus luteum (source of progesterone and estrogen) will disintegrate resulting in a decrease in the level of progesterone and estrogen. Thus, the endometrial lining of the uterus sloughs off and menstruation begins, marking a new cycle.

LH is secreted by anterior pituitary which inhibits secretion of FSH, stimulate maturation and rupture of Graafian follicle and release of ovum. LH also stimulates the formation of corpus luteum (the luteal/secretory phase; days 15-28) from ovulated Graafian follicle which in turn secretes estrogens and progesterone. In absence of implantation, progesterone and estrogens exerts negative feedback control over the anterior pituitary’s secretion of LH and causes degeneration of corpus luteum in the ovary. The lower progesterone level, as caused by disintegration of corpus luteum, results in disintegration of endometrium thereby initiating the next menstrual cycle. Thus, corpus luteum activity is under the regulation of estrogen and progesterone via negative feedback control. LTH (luteotropic hormone/prolactin) is secreted by the anterior pituitary gland and targets mammary gland to stimulate breast development and milk production after baby birth. Estrogens serves to stimulate the growth of the uterus and the vagina, is necessary for egg maturation as well as for the development of the secondary sex characteristics in females. Thus, the correct answer is A. 

• LH and FSH are pituitary hormones. 
• These hormones are essential for the growth of follicle from day 1 to day 15 of the menstrual cycle.
• On the 15th day, high level of LH secretion ( known as LH surge ) causes release of the ovum from Graafian follicle.
• The release of ovum is absolutely essential for having a baby in normal adult females.

The reproductive cells contain only half the number of chromosomes as compared to the normal body cells of an organism. The human sperm and egg have 23 chromosomes each. So when they fuse together, the zygote formed has 23+23=46 chromosomes. So the required ratio is 46 : 23, i.e., 2 : 1.

In the female reproductive system, the perineum is the area that lies between the vaginal opening and the anus. It represents the most inferior part of the pelvic outlet. Thus it lies above the external genitalia.

The glans is a vascular structure of the clitoris. The clitoris is composed of multiple parts: the glans, the clitoral body, and the paired crura and vestibular bulbs. The glans clitoris is the name of the part that most people call the “clitoris.” It is the external part of the clitoris, about the size of a pea, and is located above the urethra. Because the glans is the most highly innervated area of the clitoris, it’s extremely sensitive to touch.

The cell that results from the asymmetric division of an oocyte is a polar body. In animals and humans, polar bodies are produced after every meiotic division. They are relatively smaller in size due to less cytoplasm compared to the gametocyte that will become the ovum. This is essential so that much of the cytoplasm is available and the chromosomal content is halved at the time of fertilization. The polar bodies will eventually degenerate.

Suprarenal glands secrete adrenaline, testis secrete testosterone, pitutary gand secrete oxytocin and ovaries produce estrogen.

During the follicular phase, the secretion of FSH happens and this leads to the development of a mature follicle (Graafian follicle). This process of formation of a mature female gamete is called oogenesis. The FSH level increase causes the development of follicles and secretion of estrogen by the growing follicles. Rapid secretion of LH leads to the rupture of Graafian follicle and release of ovum called ovulation. This phase is followed by the remaining parts of Graafian follicle transform into the corpus luteum.