Behaviour of the ZW sex bivalent in the snake Bothrops jararaca.
The behavior of the ZW sex bivalent was investigated in female meiosis of the poisonous snake Bothrops jararaca. The Z is euchromatic and synapses end to end with the W. The W chromosome shows a heterochromatic segment distally in the short arm. Pairing occurs between the long arm of the W and the slightly longer arm of the mediocentric Z. A sex vesicle, similar to the one found in the XY placental mammals, does not occur in snakes. The Z and W chromosomes segregate reductionally in the first meiotic division and equationally in the second.
D000818:Animals; D005260:Female; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D008938:Mitosis; D009865:Oocytes / Q000648:ultrastructure; D012730:Sex Chromosomes / Q000648:ultrastructure*; D012911:Snakes / Q000235:genetics*