Pseudoautosomal region
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The pseudoautosomal regions or PARs are homologous sequences of nucleotides found within the sex chromosomes of species with an XY or ZW mechanism of sex determination.
PAR1 contains 16 genes, with PLCXD1 as the furthermost PAR1 gene at the distal telomeric end and XG at the boundary of PAR1 at the centromeric end. PAR2 contains 3 genes, with SPRY3 at the centromeric boundary and IL9R at the distal telomeric end.
Monotreme
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Monotremes are mammals of the order Monotremata. They are the only mammals still in existence which lay eggs, rather than bearing live young. The five extant monotreme species are the platypus and the
Pseudoautosomal region
…X and Y chromosomes in humans and great apes (X and Y are 154 Mbp and 62 Mbp in total). PAR2 is at the tips of the long arms, spanning 320 kbp. The monotremes, including the platypus and echidna, have a multiple sex chromosome system, and consequently have 8 pseudoautosomal regions. The locations of the PARs…
Monotreme collage
Platypus
Short-beaked echidna
A model of the extinct monotreme Steropodon at the Australian Museum