Explanation:

• The testis is the primary reproductive organ in males. The testes are situated outside the abdominal cavity within a pouch called the scrotum. The scrotum helps in maintaining the low temperature of the testes (2–2.5^o C lower than the normal internal body temperature) necessary for spermatogenesis.
• Testis performs dual functions as a primary sex organ as well as an endocrine gland. The testis is composed of seminiferous tubules and stromal or interstitial tissue. The Leydig cells or interstitial cells, which are present in the intertubular spaces produce a group of hormones called androgens mainly testosterone.
• Testosterone plays a key role in the development of male reproductive tissues such as the testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.
• So the correct option is ''Testosterone''

Additional Information 

• Insulin is a hormone secreted by the β cells of islets of Langerhans. Insulin is released into the bloodstream to lower down blood sugar levels and prevent hyperglycemia.
• Progesterone: It is an ovarian hormone. It prepares the inner uterine lining called the endometrium for receiving the embryo and implantation.
• Progesterone inhibits the uterine contraction so that the pregnancy can be maintained. For this reason, it is called the pregnancy hormone.
• Thyroid-stimulating hormone (TSH): It is secreted by the anterior pituitary.TSH stimulates the synthesis and secretion of thyroid hormones from the thyroid gland

The correct answer is Progesterone.

Key Points

Concept:

• Menstrual cycle: The rhythmic series of changes that occur in the reproductive organs of female primates (monkeys, apes, and human beings) is called the menstrual cycle.
• It is repeated after every 28/29 days. 
• The menstrual cycle has four phases:

1. Menstrual phase
2. Follicular phase
3. Ovulatory phase 
4. Luteal phase

Explanation:

• During the ovulatory phase, at about the 14th day of the cycle, there is a rupture of the graffian follicle and the ovum gets released.
• The ruptured Graffian follicle soon gets transformed into the Corpus luteum.
• The Corpus luteum gets stimulated by the rising levels of LH and starts secreting the Progesterone hormone.
• Progesterone hormone is required for the maintenance of the endometrium lining of the uterus.
• In case if pregnancy does not occur after ovulation the levels of progesterone start to fall down and this leads to the disintegration of the endometrium lining causing menstruation.
• Thus, lowering of progesterone hormone causes menstruation, as it is required for the maintenance of the endometrium lining, and for this reason, only progesterone is also called the pregnancy hormone.​

Additional Information

• Thyroxine: It is an endocrine secretion of the thyroid gland. The thyroid gland requires 120 microgram Iodine per day for the production of thyroxine It regulates the basal metabolic rate of the body.
• Estrogen, or Oestrogen: It is a sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. 
• Follicle-stimulating hormone: It is one of the hormones essential to pubertal development and the function of women's ovaries and men's testes. In women, this hormone stimulates the growth of ovarian follicles in the ovary before the release of an egg from one follicle at ovulation

Concept:

• Sperm is the male gamete. The sperm unites with (fertilizes) an ovum (egg) of the female to produce a new offspring.
• Spermatids is haploid cells formed by meiotic division of spermatocytes and develops into a spermatozoon after maturational events.

Explanation:

• Spermiation is the process by which the mature sperms are released from Sertoli cells.
• Spermiogenesis is the final stage of spermatogenesis, in which spermatids are transformed in the form of mobile spermatozoa.
• Spermatogenesis is the process of the production of sperms from the immature male germ cells.
• Spermatosis is not a valid term used for any step.

Additional Information

• The process of formation of sperms is called spermatogenesis. It involves 3 phases:

1. In the multiplication phase, male germ cells also called spermatogonia, which undergo mitotic divisions to form a large number of spermatogonia.
2. In the growth phase, spermatogonia prepare for meiotic division by increasing their size and called as primary spermatocytes (46 chromosomes).
3. In the maturation phase, primary spermatocyte undergoes the first meiotic division and produce 4 haploid cells called secondary spermatocytes (23 chromosomes), which after the second meiotic division produces four equal, haploid spermatids.

The correct answer is Placenta.

Key Points

Explanation:

• The placenta is a structure that connects or joins the developing fetus to the uterine wall to allow different physiological processes like nutrient uptake, waste elimination, and gaseous exchange via the mother’s blood supply i.e it provides a vascular connection between fetus & uterus.
• The placenta helps to fight against internal infection and produce hormones to support pregnancy,
• It is well developed in Eutheria. In marsupials, the embryo develops incompletely in the uterus.
• Based on the distribution of villi, the placenta can be divided into 7 major types

1. Diffused type placenta
2. Cotyledonary placenta
3. Intermediate type placenta
4. Zonary placenta
5. Cotyledonary placenta
6. Discoidal placenta
7. Metadiscoidal placenta

Additional Information

• Corpus luteum: It is a structure formed from the Graffian follicle. After Ovulation, the ruptured Graffian follicle gets transformed into the Corpus luteum. 
• Leydig cells: The cell that secretes androgen hormones in the human being is the Cells of Leydig. Cells of Leydig are found in testicles (male reproductive organ).
• Fimbriae: The infundibulum has several finger-like projections called fimbriae, they move closer to the ovaries during ovulation to collect the released ovum.

Key Points

Mammary gland - 

• A functional mammary gland is characteristic of all female mammals.
• The mammary glands are paired structures (breasts) that contain glandular tissue and a variable amount of fat.
• The glandular tissue of each breast is divided into 15-20 mammary lobes containing clusters of cells called alveoli.
• The cells of alveoli secrete milk, which is stored in the cavities (lumens) of alveoli.
• The alveoli open into mammary tubules.
• The tubules of each lobe join to form a mammary duct.
• Several mammary ducts join to form a wider mammary ampulla which is connected to the lactiferous duct through which milk is sucked out.  
• Thereby, cells of the alveoli are the milk-secreting cells of the alveoli.

Important Points 

• Mammary glands are modified sweat glands that secrete out milk as an exocrine secretion

Concept-

• A large number of couples all over the world including India are infertile, i.e., they are unable to produce children in spite of unprotected sexual cohabitation.
• Specialised health care units (infertility clinics, etc.) could help in the diagnosis and corrective treatment of some of these disorders and enable these couples to have children.
• Where such corrections are not possible, the couples could be assisted to have children through certain special techniques commonly known as assisted reproductive technologies (ART).

Explanation-

• Intracytoplasmic sperm injection (ICSI) is the specialised procedure to form an embryo in the laboratory in which a sperm is directly injected into the ovum.
• In ICSI, single live sperm is injecting directly into the centre of a human egg.
• The ICSI technique is used to help those couples in fertilization with severe male factor infertility.

Therefore the method of directly injecting sperm into the ovum in Assisted Reproductive Technology is called ICSI.

Additional Information

GIFT - (gamete intrafallopian transfer)

• Transfer of an ovum collected from a donor into the fallopian tube of another female who cannot produce one but can provide a suitable environment for fertilization and further development. 

ZIFT - (zygote intrafallopian transfer) 

• The zygote or early embryos (with up to 8 blastomeres) could then be transferred into the fallopian tube (ZIFT–zygote intrafallopian transfer) and embryos with more than 8 blastomeres, into the uterus (IUT – intrauterine transfer), to complete their further development.

ET - (embryo transfer)

• In this method, popularly known as the test-tube baby programme, ova from the wife/donor (female) and sperms from the husband/donor (male) are collected and are induced to form zygote under simulated conditions in the laboratory.

Concept:

• The process of formation of a mature female gamete is called oogenesis which is markedly different from spermatogenesis. 
• Oogenesis is initiated during the embryonic development stage when a couple of million gamete mother cells (oogonia) are formed within each fetal ovary; no more oogonia are formed and added after birth.
• These cells start division and enter into prophase-I of the meiotic division and get temporarily arrested at that stage, called primary oocytes.

Explanation:

• Each primary oocyte then gets surrounded by a layer of granulosa cells and is called the primary follicle. 
• A large number of these follicles degenerate during the phase from birth to puberty.
• Therefore, at puberty, only 60,000-80,000 primary follicles are left in each ovary.
• The primary follicles get surrounded by more layers of granulosa cells and a new theca and are called secondary follicles.
• The secondary follicle soon transforms into a tertiary follicle which is characterized by a fluid-filled cavity called the antrum.
• So the fluid-filled cavity called the antrum is found in the tertiary follicle.

​Additional Information 

• The tertiary follicle further changes into the mature follicle or Graafian follicle.
• During ovulation, the ovum gets released from the graffian follicle and it gets ruptured.
• After Ovulation, the ruptured Graffian follicle gets transformed into the Corpus luteum.
• Corpus luteum secretes Progesterone which is required for the maintenance of pregnancy

Concept:

• The devices that are used to prevent unwanted pregnancies are called Birth control devices or Contraceptives.
• Various Contraceptive methods are:

1. Natural/traditional methods
2. Barrier methods - Condoms, Diaphragms, Cervical caps
3. Intra uterine devices (IUDs) - Lippes loop, Copper T, Copper 7
4. Oral contraceptives - Saheli
5. Injectables and Implants 
6. Surgical Methods - Vasectomy & Tubectomy

Explanation:

• Copper T is an intra uterine device inserted by doctors in the uterus through the vagina.
• It increases the phagocytosis of sperms in the uterus, along with this it also releases copper ions which suppress sperm motility and fertilizing capacity.
• Thus the copper used in Copper T has Spermicidal action

​

Explanation:

• Ovulation is the phase of the menstrual cycle where the ovum  gets released from the graffian follicle, this phase is regulated  by the activity of different hormones like FSH (follicle-stimulating hormone) and LH (luteinizing hormone)
• Both LH and FSH attain a peak level in the middle of the menstrual cycle (about the 14th day). 
• Rapid secretion of LH leading to its maximum level during the mid-cycle (peak of ovulation) called LH surge induces rupture of graffian follicle and thereby the release of an ovum (ovulation)
• Thus, Ovulation in mammals is caused by FSH & LH

​

Additional Information

• Thyroid-stimulating hormone (TSH): It is secreted by the anterior pituitary. TSH stimulates the synthesis and secretion of thyroid hormones from the thyroid gland
• Prolactin: It is also called lactotrophic hormone (LTH). It regulates the growth and milk formation of mammary glands.

Concept:

• The devices that are used to prevent unwanted pregnancies are called Birth control devices or Contraceptives.
• Various Contraceptive methods are:

1. Natural/traditional methods
2. Barrier methods - Condoms, Diaphragms, Cervical caps
3. Intrauterine devices (IUDs) - Lippes loop, Copper T, Copper 7
4. Oral contraceptives - Saheli
5. Injectables and Implants 
6. Surgical Methods - Vasectomy & Tubectomy

Explanation:

• Condoms are barriers made of thin rubber/latex sheath used to cover the penis in the male or vagina and cervix in females. It prevents the deposition of ejaculated semen into the vagina of the female.
• Condoms help in preventing the transmission of sexually transmitted diseases, as condoms act as a barrier between the direct contact of sexual organs during intercourse.