2. National Center for Biotechnology information
Chromosome X
Chromosome Y

3. http://press2. nci. nih. gov/sciencebehind/genetesting/genetesting21

8. External Development
Initially undifferentiated, the presence of hormones causes sexual differentiation

9. Internal Development
Initially undifferentiated, the presence of hormones causes sexual differentiation

10. Karyotype kar·y·o·type n.
The characterization of the chromosomal complement of an individual or a species, including number, form, and size of the chromosomes.
A photomicrograph of chromosomes arranged according to a standard classification.

11. Karyotype of a Human Child: Boy
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Karyotype of a Human Child: Boy

12. Karyotype of a Human Child: Girl
Karyotype of a Human Child: Girl