Why is a human cell containing 22 autosomes and a y chromosome a sperm?

Human somatic (body) cells contain two sets of 23 chromosomes. Human gametes (sperm and egg cells) contain one set of 23 chromomes -- 22 autosomes and 1 sex chromosome. Only a sperm cell can carry a y chromosome. A sperm cell can also carry an x chromosome. The ovum can carry only an x chromosome, never a y chromosome. So a cell containing 22 autosomes and a y chromosome must be a sperm cell.