Carried distinctly through men, the Y chromosome only gives a portion of the entire mitochondrial DNA.
There is in the male, in addition to the X, also a Y chromosome, which acts as its mate in synapsis and reduction.
Other evidence has shown that the Y chromosome of the male is indifferent, so far as these Mendelian factors are concerned.
The X chromosome in the male is represented by an open bar, the Y chromosome is bent.
The females that gave these results were found by Bridges to have two X's and a Y chromosome.