Primary Spermatocyte?

[anbuitachi]

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Hi EK says spermatogonium forms primary spermatocyte after going to the S phase and duplicateds DNA. However I've read in other sources (kaplan) and they say spermatogonium does a mitotic division to get primary spermatocyte... which is correct? because according to EK, S phase is before mitosis even happens so there should be no mitosis, while i assume mitotic division means it went thru mitosis?

thanks

 

[docelh]

The way I understand it, primary spermatocyte is the germ cell before it undergoes Meiosis.

 

[Silverfalcon]

I have Kaplan, and that's not what Kaplan states. 🙂

EK is right. Basically, spermatogonium, like docelh said, is a type of germ cell which undergoes replications to double the DNA concentration (note that spermatogonia are already diploid to start off with; it's just the DNA duplication). And then the resulted is primary spermatocyte, which will then go onto meiosis.

 

[JSU]

I think the same applies with a primary Oocyte. It has already gone through S phase and is frozen at prophaseI (2n) of meiosis. However, when either a primary Oocyte or Spermatocyte passes Anaphase I is it considered secondary (1n now because crossing over made each chromosome unique) or does that only happen once it goes through cytocynesis?

 

[fizzgig]

JSU someone asked a question in another thread and it seemed like you shouldn't consider the daughters haploid until cytokinesis is complete (so end of telophaseI).

 

[JSU]

JSU someone asked a question in another thread and it seemed like you shouldn't consider the daughters haploid until cytokinesis is complete (so end of telophaseI).

If your talking about daughter cells, then TBR considers them as another ploid number. During Mitosis the cell is considered 4n after Anaphase (4xeach chromosome even though some as homologues). However, during miosis, maybe we shouldnt change the ploidy number because each chromosome is now different meaning its still 2n?

 

[fizzgig]

wtf?? ok the way EK explains it ...from the visual representation of chromosomes:
| is 1 chromosome, X is one chromosome, and X X sitting side by side is two chromosomes..

EK appears to only work with 2n and n - the replicated homologue that looks like X in mitosis is only 2n --> X is considered 1 chromosome with 2 chromatids....

are the conventions this haphazard?? I don't have BR at this point....