Basic Embryo.. got confused

[ulikedaggers]

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I thought that the term "diploid" in humans always meant 46, 2n. Clearly that's not the case since secondary spermatocytes are 23,2n... I would've guessed they are 23,n.

Can someone explain?

 

[ulikedaggers]

This link makes sense to me and is what I expected.

http://en.wikipedia.org/wiki/Spermatogenesis#Stages

HY Embryo (and my course notes) says otherwise though.. They both say:

Spermatogonia (46,2n)
Primary Spermatocytes (46,4n)
Secondary Spermatocytes (23,2n)
Spermatids (23,1n)

 

[Pharmdmba1978]

Primary spermatocytes have 23 pairs of homologous chromosomes and a total of 92 sister chromatids. After the first meiotic division the total number of chromosomes is reduced to 23; however, these 23 chromosomes still have their sister chromatids for a total of 46 chromatids. After the second and final meiotic division the sister chromatids are separated. This leaves 23 single chromosomes per-spermatozoa.

 

[ulikedaggers]

Primary spermatocytes have 23 pairs of homologous chromosomes and a total of 92 sister chromatids. After the first meiotic division the total number of chromosomes is reduced to 23; however, these 23 chromosomes still have their sister chromatids for a total of 46 chromatids. After the second and final meiotic division the sister chromatids are separated. This leaves 23 single chromosomes per-spermatozoa.

Got it. Thank you.