Developmental evolution: The unbearable likeness of beings Greg Gibson  Current Biology  Volume 11, Issue 9, Pages R345-R348 (May 2001) DOI: 10.1016/S0960-9822(01)00190-7

Fig. 1 Variability in the vulval cell lineages of three nematode genera. The vulva is derived from three precursor cells that differentiate from the hypodermis giving rise to the 1° (P6.p, blue) and 2° (P(5,7).p, red) lineages. In Caenorhabditis, P(3,4,8).p (purple) normally fuse as a syncitium (s) with the adjacent hypodermis, but there is variation within and between species as to whether P3.p (grey) divides first. In addition, this cell has variable capacity to adopt a partial vulval fate after ablation of P(4-8).p. In Oscheius, P4.p and P8.p also show variable numbers of cell divisions before they normally become part of the syncitium, and there is variation for their capacity to adopt vulval fates after ablation of P(5-7).p. In Pristionchus, P(3,4).p undergo apoptosis, while P8.p adopts a different 4° fate, unless P(6,7).p are ablated in which case it becomes vulval (in P. lheritieri). P5.p can switch from 2° to 1° fate under such conditions throughout the genus, again with variable frequency. Current Biology 2001 11, R345-R348DOI: (10.1016/S0960-9822(01)00190-7)