Human Reproduction and Contraception

Progesterone is a hormone released by the corpus luteum in the ovary. It plays important roles in the menstrual cycle and in maintaining the early stages of pregnancy. It may also be involved in the growth of certain cancers. During the menstrual cycle, when an egg is released from the ovary at ovulation (approximately day 14), the remnants of the ovarian follicle that enclosed the developing egg form a structure called as the corpus luteum. This releases progesterone and, to a lesser extent, oestradiol. The progesterone prepares the body for pregnancy in the event that the released egg is fertilised. If the egg is not fertilised, the corpus luteum breaks down, the production of progesterone falls and a new menstrual cycle begins. Estrogen or oestrogen is the primary female sex hormone and is responsible for development and regulation of the female reproductive system and secondary sex characteristics. Follicle stimulating hormone is produced by the pituitary gland. It regulates the functions of both the ovaries and testes. Lack or insufficiency of it can cause infertility or subfertility both in men and women. In females, an acute rise of LH ("LH surge") triggers ovulation and development of the corpus luteum. In males, where LH had also been called interstitial cell–stimulating hormone (ICSH), it stimulates Leydig cell production of testosterone. It acts synergistically with FSH. 

The clot is made up of blood cells, fibrins and endometrial tissues. Since the blood passes from uterus quickly then there is no time for anticoagulants to act. So, clots cannot be formed easily.

The menstrual cycle is the cycle of natural changes that occurs in the uterus and ovary as an essential part of making sexual reproduction possible. The length of it is an average of 28 days. So, blank 1 is 28 days.
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction, It leads to the beginning of menstrual cycles in women. So, blank 2 is the menstrual cycle.
Menarche is the first menstrual cycle in females. So, blank 3 is menarche.
This cycle begins generally at the age of 12-13 and ends at the age of 45-55. So, option 4 is 45-50.
Menopause marks the end of menstrual cycle. So, blank 5 is menopause.
At around mid-cycle, when the egg is mature, it gets released from the ovary, pushed down to fallopian tube and is available to be fertilized in the process called ovulation. This occurs around 13th-14th day. So, blank 6 is 13$^{th}$ or 14$^{th}$ day and blank 7 is ovulation.
Progesterone is an endogenous steroid hormone and is secreted in the ovaries by the corpus luteum. So, blank 8 is progesterone.
After being released from the ovary, the egg is swept into the fallopian tube by the fimbria, which is a fringe of tissue at the end of each fallopian tube. So, blank 9 is fallopian tube
Thus, the correct answer is option (A), '(1) 28 days, (2) puberty, (3) menarche, (4) 45-50 years, (5) menopause, (6) 13th or 14th days, (7) ovulation, (8) progesterone, (9) fallopian tube'.

The mammary glands of the female undergo differentiation after the pregnancy and starts producing milk towards the end of it, called lactation and the milk produced during these initial few days is referred to as colostrum. This contains many antibodies that is essential for the new born babies to develop resistance against any pathogen attack or disease. During oogenesis the gamete mother cell undergoes meiosis division to form the primary oocyte and this further divides into the secondary oocyte and a polar body by means of an unequal division. 

After ovulation the lining of the (graafian) follicles grow inward, forming corpus luteum (yellow body), which temporary function as endocrine tissue. It secrete estrogen and progesterone, which stops additional ovulation, and thickening of uterine wall. If pregnancy does not occur within 14 days corpus luteum degenerates and menstruation follows.

Parturition can be defined as the act of expelling the full term young ones from the mother's uterus at the end of the gestation period. In other words, the process of delivery of the fetus is known as parturition.

The hypothalamus secretes the Gonadotropin-releasing hormone which is responsible for menstruation sequence. The GnrRH repressed by the prolactin hormone, which encourages the production of milk. Without the GnRH release, the menstrual cycle wont begin a new event of pregnancy.

• Parturition is a phenomenon of giving birth. It is a process of delivering a child from the womb to the outside. It is usually initiated by the release of oxytocin hormone. 
• This hormone increases the contraction of uterine muscles. Prostaglandins are synthesized and released in response to the oxytocin hormone. Also, an increase in estrogen and progesterone ratio indicates the initiation of the parturition process. 
• Prolactin hormones are released after the parturition in order to secrete the milk from the mammary gland.

Estrous cycle, or oestrous cycle, is the reproductive cycle found in most mammalian placental females, whereby there are recurring periods when the female is fertile and sexually receptive (estrus) interrupted by periods in which the female is not fertile and not sexually receptive (anestrus). 

The gestation period is calculated from the first day of the last menstrual period. This is used to calculate the expected date of delivery (EDD).

Development of fetus from the time of conception until birth is called as gestation period.

Parturition is also called as childbirth. It is the act of delivering baby from uterus. Gestation is a period of developing embryo from conception to birth. It is a duration considered between pregnancy and birth. Ovulation is a process of releasing of egg from the ovary or Graafian follicle. Implantation is the process in which fertilized egg or zygote adheres or attaches to the endometrium wall of the uterus. Conception is the act of conceiving  a baby. In this, zygote is formed from the fusion of egg and sperm.

The duration of pregnancy from conception till birth is known as gestation. It occurs for a duration of 40 weeks. The release of eggs from the ovaries (or the mature graafian follicle) is known as ovulation. Implantation is the process in which the embryo in the blastocyst stage is implanted in the uterus. When the egg fuss with the sperm resulting in the formation of zygote it is known as conception. Parturition is the act of childbirth in which the baby is delivered from the uterus. So, the correct option is 'A - 3, B - 4, C - 2, D - 1, E - 5'.

• The increased levels of oxytocin at the time of parturition are responsible for vigorous uterine contractions and the dilation of the uterus. 
• The estrogen-progesterone ratio increases during the end of the 3rd trimester which results in the increased ability of the mammary glands for lactation.