Question: how many chromosomes after fertilization?
Answer: In a human egg or sperm, there are 23 chromosomes, one of which is an X or Y. A human egg is haploid (has 23 chromosomes) and a sperm is haploid (has 23 chromosomes). Upon fertilization, the new baby now has the 'correct' human number of 46 chromosomes in each of its somatic cells.