Quick Question on ovum zygote oocyte

[Mrhyde]

Hi ................................. I want to clarify that I am correct with these statements :
Oocyte is immature egg cell
Oogenesis produces the end result of the ovum from an oocyte
Ovum is a mature egg cell

I saw the following line I wrote in my old notes but I think I wrote a mistake looking back at it, and I want to know if you think I did make a mistake :

"If the oocyte is not fertilized by a sperm in the Uterine/Fallopian tubes within 24 hours after ovulation, then the oocyte never completes the second meiotic division, and so it never technically becomes an ovum."


--> So no fertilization = No 2nd Division by Secondary oocyte in Uterine tubes


However, if the secondary oocyte is fertilized by a sperm, it immediately finishes its second meiotic division, releases a polar body to leave only a haploid female genome in the ovum and then becomes a zygote as the nuclei of the sperm and egg fuse together.

My confusion from this paragraph :

So does this mean that an Ovum is only an Ovum for a few seconds lol ? Since once the sperm enters we would have a Zygote and no longer an Ovum. But we only get an Ovum from an Oocyte when the sperm starts to enter which triggers the secondary oocyte into transforming into its final form of the ovum.

????????????????

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[eternal-sunshine]

I have this written in my notes:

1. completion of meiosis II in the secondary oocyte

• in humans, sperm penetration triggers Meiosis II in the oocyte producing EGG ovum and polar body

2. Fusion of nuclei and replication of DNA

• sperm and ovum nuclei fuse forming a ZYGOTE nucleus consisting of 23 pairs of chromosomes
• each chromosome replicates so it consists of 2 identical chromatids (--> 46 chromatids)

So essentially, zygote is the result of fusion of nuclei of ovum and sperm.

Hope this helped!

 

[Mrhyde]

Thanks . But that did not help answer my question lol Basically if the Secondary oocyte only does the secondary meiotic division if it is fertilized in the uterine tubes , it will then become the ovum officially ..... BUT then whats the difference of calling that an ovum or zygote ? since by it being fertilized it is then now the zygote BUT it also only becomes the mature ovum once its fertilized since that's the only trigger for the 2nd meiotic division? So its like both the ovum and the zygote are the same thing even though by definition they are completely different but we can only call the secondary oocyte an ovum once it does the division which is only triggered by a sperm ? Do you get what i am saying lol