How many chromosomes are in a human zygote?

A healthy human zygote has a total of 46 chromosomes: 23 from the egg and 23 from the sperm. While it is relatively rare, there are cases where the zygote will have an extra chromosome, which can cause a variety of birth defects like Down syndrome. read more

Haploid gametes have 23 chromosomes each and when they are fused together- 23 chromosomes of ovum and 23 chromosomes of sperm, add to form 46 chromosomes in a ZYGOTE. So, a zygote like any other normal human being has 46 chromosomes or, 23 pairs of chromosomes. read more

Normal human zygotes all have 46 chromosomes organized into 23 pairs, which is the same number that most adult humans have. Together, these 46 chromosomes contain an estimated 25,000 genes, according to the National Human Genome Research Institute. read more