Figure 4. Y* meiosis.

During metaphase of a 4S gamete, the altered pseudoautosomal region (PAR) of the Y* chromosome pairs with the X PAR in an inverted fashion. To demonstrate the arrangements of the domains of the pseudoautosomal region (PAR) throughout mitosis and recombination of X and Y*, the PAR region has been depicted as three domains based on their locations relative to the normally active centromere (depicted here as a white circle on X): proximal (a = red) domain; middle (b = orange) domain; and distal (c = green) domain. When genetic material is exchanged between X and Y* in the inverted orientation during recombination, the recombined chromatids are different in structure and content of sex chromosome genes compared to the non-recombined chromatids. After recombination and separation of the four unique chromosomes after telophase 1 and 2, four male gametes are produced that differ in content of the following paternal sex chromosomes: X, X^Y*, Y^*X, and Y*. The non-pseudoautosomal region of X (NPX), and the non-recombining region of Y (NRY), are depicted in pink and yellow, respectively. The active Y* centromere is depicted as a white circle, and the inactivate centromere is a circle with stripes. Sry, the sex determining region of Y (blue bar in NRY).