Complex sentence: Mees'lines or Aldrich-Mees' lines are lines of discoloration across the nails of the fingers and toes after an episode of poisoning with arsenic or thallium or other heavy metals.
Split into simpler sentences: Mees'lines or Aldrich-Mees' lines are lines of discoloration across the nails of the fingers and toes. They appear after an episode of poisoning with arsenic or thallium or other heavy metals.