W chromosome in the Indian water snake (checkered keel back) Natrix piscator (Colubridae).
D000818:Animals; D001854:Bone Marrow Cells; D002455:Cell Division; D004171:Diploidy; D005260:Female; D007621:Karyotyping; D008297:Male; D012730:Sex Chromosomes; D012911:Snakes / Q000145:classification / Q000166:cytology*