how sex in poultry birds and humans determined
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In birds, the sex of the embryo is determined by the egg, not the sperm (as it is in humans). ... In those systems the sex is determined by the sperm, by what the male contributes to the offspring.
In birds, the sex of the embryo is determined by the egg, not the sperm (as it is in humans). ... In those systems the sex is determined by the sperm, by what the male contributes to the offspring. By contrast, birds have a ZW system of sex determination (shared with butterflies, moths, fish and reptiles).
Most mammals, including humans, have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. ... Chromosomal sex is determined at the time of fertilization; a chromosome from the sperm cell, either X or Y, fuses with the X chromosome in the egg cell.