Feb 07, 2023
Learn what is Gametogenesis, Mitosis vs Meiosis, Oogenesis in this detailed article which will upgrade your NEET-PG exam preparation.
The process of producing gametes from haploid progenitor cells is called gametogenesis. Different differentiation programmes are used in animals and higher plants to produce the two physically distinct types of gametes (male and female). Animals produce a tissue called the germ line that is specifically responsible for developing gametes.
Zygote has maternal and paternal nuclei. The genetic make-up of a zygote is referred to as [2n, 2N]. Zygote further divides and forms → Blastocyst. Blastocyst has an Inner Cell Mass (ICM). ICM has an epiblast. This epiblast forms Primordial Germ Cells (PGCs). PGCs are the 1st sex cells of the body
The formation of gametocytes can be summarized as below
Primary & Secondary Gametocytes
n → refers to the number of chromosomes
N → refers to the amount of DNA
Genetic make-up of male and female gametes → [n, N]Genetic make-up of zygote → [2n, 2N]
Also read: How to Prepare Anatomy for PG Entrace Exams ?
It is also known as Equational division (because the chromosome number remains the same). Before any cell division, DNA duplication occurs. DNA duplication occurs in the ‘S phase’ or the ‘Synthesis phase’ of the Interphase. This means that the cell changes from a [2n, 2N] to [2n, 4N]. The cell remains diploid [2n] but the DNA amount is doubled [4N]. The sister chromatids are available.
It is also known as → Reduction division (because the chromosome number is reduced to half). DNA duplication occurs in the ‘S phase’ or the ‘Synthesis phase’ of the Interphase.
Now that you’ve reached till here, complement your learning further with this detailed video lecture on Gametogenesis by Dr Prassan Vij:
Primordial germ cell (PGC) differentiates to form the oogonium and further the primary oocyte via the process of mitosis. Primary gametocyte is the largest of all the cells in the process of gametogenesis. Primary oocyte undergoes meiosis.
|Important Information: |
1st Polar Body → is formed after LH Surge, but before fertilization.
2nd Polar Body → is formed after fertilization.
Also Read: Inguinal Canal & Spermatic Cord - NEET PG
Normally, menstrual cycle duration is 28 days (average). Day 1 → here, refers to the 1st day of the last menstrual period (LMP). If it is a 28-days cycle, then ovulation will occur on Day 14 (mid-cycle) of the menstrual cycle.
|Important Information: |
Capacity of sperms to fertilize the ovum is → 2 days / 48 hours after ejaculation.
However, sperms can survive for about 5-10 days after ejaculation inside a female.
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