In planarians, they stick around into adulthood, where they become known as adult pluripotent stem cells or
neoblasts. Scientists believe these
neoblasts hold the secret to regeneration.
For instance, mortalin was shown to be constitutively expressed in planarian
neoblasts, and its experimental silencing resulted in inability to regenerate and maintain the normal cell turnover (Conte et al., 2009).
In uninjured planaria,
neoblasts are distributed throughout the parenchyma (mesenchyme), and only mitotic cells serve as the source of replacement cells during tissue renewal (Newmark, 2007).
Histological investigations have suggested that the remarkable size of these hyperplasic ovaries versus normal ovaries is due to a greater proliferation of
neoblasts transforming into oogonia (Gremigni and Banchetti, 1972; Benazzi, 1974).
The epithelium is disordered, with most gonial cells (or
neoblasts) and scarce sperm cells in the tubule lumen.
The ability to follow individual
neoblasts opens the door to uncovering the molecular cues that help planarian stem cells navigate to the site of injury and ultimately may allow scientists to provide therapeutic stem cells with guideposts to their correct destination.
Scattered within the planarian body,
neoblasts apparently remain in an unspecialized, stem cell state, which enables them to differentiate into any cell type.
This amazing plasticity relies on the presence of a population of adult pluripotent stem cell, the
neoblasts, which are able to become any type of cell.
In the planarian flatworm Schmidtea mediterranea, certain dividing cells called
neoblasts have long been identified as essential for the regeneration that repairs the worm's tissues.
Planaria rely on these cells, called
neoblasts, to regenerate lost body parts.
Evidence that
neoblasts are totipotent stem cells and the source of blastema cells.
The anatomy and histology of bud-formation in the serpulid Filograna implexa, together with some cytological observations on the nuclei of the
neoblasts. J.