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48.Oogenesis
Hi guys I am back with another video , so this is the last video of the gametogenesis series and we will be ending it with oogenesis right in this video .so what is oogenesis ? Oogenesis is basically the formation of oocyte which is the female gamete . Oogenesis starts at the 8th week of intrauterine life . There are 6to 7 primordial follicles at the 28th week of intrauterine life . Some of the primordial follicles enters the meiosis 1 and then it forms the primary oocyte . 1 to 2 millions are only left at birth after birth after the primary oocyte survives the wave of atresia .3 to 4 lakhs are left by puberty . The primary oocyte gives rise to secondary oocyte and the first polar body . Now the first polar body is basically the extra generic material . The primary oocyte forms the secondary oocyte by undergoing through meiosis 1 division and along with secondary oocyte it also forms the first polar body . So the first polar body is nothing but the extra genetic material , primary oocyte is diploid in nature that is 2n whereas the secondary oocyte is haploid in nature that is n . Meiosis 1 resumes at the time of ovulation that is the secondary oocyte and the first polar body is released during ovulation. Then the secondary oocyte undergoes through meiosis 2 division which is arrested till fertilization , after fertilization the second polar body and one ovum is released . Now the second polar bodies are three in numbers . This is all about Oogenesis , see you in the next video , thank you !
