#retrogression__degeneration  passing from a more complex to a simpler biological form
  supertype:  transformation.change__transmutation__shift  a qualitative change
  subtype:  abiotrophy  a loss of vitality and a degeneration of cells and tissues not due to any apparent injury
  subtype:  cataplasia  (biology) degenerative reversion of cells or tissue to a less differentiated or more primitive form

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