Y Chromosome Sperm
The idea that the Y chromosome was named after its similarity in appearance to the letter "Y" is mistaken. All chromosomes normally appear as an amorphous blob under the microscope and only take on a well-defined shape during mitosis . This shape is vaguely X-shaped for all chromosomes. It is entirely coincidental that the Y chromosome, during mitosis , has two very short branches which can look merged under the microscope and appear as the descender of a Y-shape.