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Menstrual cycle
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Kalpesh J Gadhvi is teaching live on Unacademy Plus

Kalpesh J Gadhvi
Final Year MBBS Student | Discount code for Plus -"KalpeshGadhvi" | On the way to make More Doctors which Our Country Needs most

Unacademy user
thanks very much sirji
sir ,is it necessary for mensturation to be occur after 28-29 days???then why in some female this period is not regular
sir, the meiosis2 which takes place in the graafian follicle happens at the time of ovulation or the meiosis 2 takes place before only but the ovum is not released ?
does progesterone produce corpus luteum or corpus luteum produce progesterone??!
Maulik ramanandi
5 months ago
corpus lutetum produce progesterone hormone.
Sir what is polar body and there function
sir tell me function of polar body
Swarna Madhuri
a year ago
polar body involves in sex determination polar body is also known as Barr body and if it is present in chromosomes ,the baby will be a girl.
Izazul islam
2 months ago
does the polar body will disintegrate....and die
  1. Human reproduction Presented by Kalpesh gadhvi

  2. About me Myself Kalpesh gadhvi I am pursuing MBBS at PDU MEDICAL COLLEGE RAJKOT My hobbies are playing cricket and listen music You can follow me on unacademy by pressing follow button on my profile If you like my courses than you can rate review recommend and share it. . . . . .

  3. Menstrual cycle

  4. . Menstrual cycle is the reproductive cycle in all primates and begins at puberty (menarche) . In human females, menstruation occurs once in 28 to 29 days. The cycle of events starting from one menstruation till the next one is called the menstrual cycle. . During the middle of the menstrual cycle, one ovum is released (ovulation) . The cycle starts with the menstrual flow (3 to 5 days), caused due to the breakdown of the endometrium of the uterus. Blood vessels in liquid state are discharged, but this occurs only when the ovum is not fertilised.

  5. . It is followed by the follicular phase.ln this phase, the primary follicles mature into the Graffian follicles. This causes the regeneration of the endometrium. . These changes are brought about by ovarian and pituitary hormones. In this phase, the release of gonadotropins (LH and FSH) increases. This causes follicular growth and the growing follicles produce oestrogen. The LH and FSH are at their peak in the middle of the cycle (14th day), and cause the rupture of the Graffian follicles to release ovum. This phase is called the ovulatory phase.

  6. amus GnRH Anterior pituitary Mideycle peak of LH (triggers ovulation) FSH LH Blood levels of FSH LH levels LH Growth of follicle-Ovulation Corpus Oestrogen Progesterone Blood levels of Endometrium of uterus ogcstcronc Ocstrogen Menstruation days 4 hilicular phasco -al phase of menstrual evcle menstrual evcle

  7. . The remains of the Graffian follicles get converted into the corpus luteum, which secretes progesterone for the maintenance of the endometrium. In the absence of fertilisation, the corpus luteum degenerates, thereby causing the disintegration of the endometrium and the start of a new cycle. . In humans, the menstrual cycle ceases to operate at the age of 50 years. This phase is known as the menopause.

  8. Fertilization and implantation

  9. During coitus, the semen is released into the vagina, passes through the cervix of the uterus and reaches the ampullary-isthmic junction of the fallopian tube. . The ovum is also released into the junction for fertilisation to occur. . The process of fusion of the sperm and the ovum is known as fertilisation. . During fertilisation, the sperm induces changes in the zona pellucidaand blocks the entry of other sperms. This ensures that only one sperm fertilises an ovum. . The enzymatic secretions of acrosome help sperm in penetration to ovum cytoplasm.

  10. . This causes the completion of meiotic division of the secondary oocyte, resulting in the formation of a haploid ovum (ootid) and a secondary polar body. . Then, the haploid sperm nucleus fuses with the haploid nucleus of the ovum to form a diploid zygote. . Mitosis starts as the zygote moves through the isthmus of the oviduct (cleavage) and forms 2, 4, 8, 16 daughter cells called blastomeres. The 8-16 cell embryo is called a morula,which continues to divide to form the blastocyst. The morula moves further into the uterus.

  11. Pregnancy, parturition and lactation