I was reading about the viability of animal hybrids and found the following sentence here:

Previously, this idea was not widely accepted, because, in general, different species have different numbers of chromosomes, the structures within cells that contain genes. This difference can prevent the normal development of the embryo, as each chromosome that came from the male parent must be aligned with an equivalent chromosome from the female parent when the fertilized cell divides for the first time. Without this proper alignment, the cell usually cannot divide and, thus, dies.

However, I couldn't find more information about the first zygotic division and this alignment of homologous chromosomes. This bugged me a little since, during mitosis, there's no alignment of that chromosomes.

So, anyone could clarify what exacly happens at chromosome level during fecudation and in the first zygotic division? How can this block the development of an "embryo" formed by two very distant species' gametes?


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