embryonic cleavage confusion

[deleted738762]

DAT destroyer says the embryo does not increase in overall size during cleavage. Bootcamp one of the practice exam says
· embryonic cleavage, the total cell mass stays the same as the number of cells increases. Therefore, during cleavage divisions, the number of blastomeres increases and the size of the blastomeres decreases

Can someone clear this up? Thanks

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[artist2022]

Mass stays the same, but the number of cells increases. This means that they must be getting smaller, since the mass has to stay the same.
ex. 10 cells, volume of 1cm3 each = 10 cm3 total volume
20 cells (number increased!) of 0.5cm3 volume (volume decreased!) = 10 cm3 total volume still.
Blastomere is a cell- the number increased (10 to 20), but the size (volume) of each one decreased (1cm3 to 0.5cm3)
Hope this helps.

 

[deleted678432]

Imagine a solid sphere that the cells cannot break through during cleavage. As each cell divides, it will essentially take up the same area, but will now be two cells instead of one.
If one cell has a volume of one units, it will divide and become two cells, each having 0.5 volume. These divide and become 0.25, and so on. Obviously this is a rough estimate, but the main purpose of this that you should see is that the body just tries to bang out as many cells as possible without really taking up more space.