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Oogenesis - Anatomy & Physiology (view source)
Revision as of 11:45, 22 July 2008
, 11:45, 22 July 2008→Stages of Oogenesis
'''Stage 4'''
'''Stage 4'''
*The meiotic block is removed by the onset of puberty and the first Luteinising Hormone surge. The primary oocyte completes its first meiotic division producing a Secondary oocyte and the first polar body. The Secondary Oocyte enters Meiosis II and is arrested at metaphase II. The secondary oocyte is diploid.
*The meiotic block is removed by the onset of puberty and the first Luteinising Hormone surge. The primary oocyte completes its first meiotic division producing a Secondary oocyte and the first polar body. The Secondary Oocyte enters Meiosis II and is arrested at metaphase II. The secondary oocyte is diploid.
*Ovulation occurs at this stage once the first meiotic division has been completed and secondary oocyte formed. The exception to this is in the case of the Bitch where ovulation occurs after stage 3 with the Primary Oocyte arrested in prophase I.
*The oocyte enlarges due to a inrease (x50) in cytoplasmic volume. The oocyte is now 100-150µm.
*Ovulation occurs at this stage once the first meiotic division has been completed and secondary oocyte formed within the dominant follicle. The exception to this is in the case of the Bitch where ovulation occurs after stage 3 with the Primary Oocyte arrested in prophase I.
*Occurs after puberty is reached.
*Occurs after puberty is reached.
'''Stage 5'''
'''Stage 5'''
*The secondary oocyte completes meiosis II producing the mature gamete, the Ova, which is haploid.
*The secondary oocyte completes meiosis II producing the mature gamete, the Ova, which is haploid.
*This stage only ocurs once fertilisation of the secondary oocyte by the sperm has occurred.
*This stage only ocurs once fertilisation of the secondary oocyte by the sperm has occurred.