The zebrafish adult retina: continuous cell genesis for growth and regeneration

MARIA PAULA FAILLACE

Montevideo

Encuentro; LATIN AMERICAN ZEBRAFISH NETWORK -FIRST MEETING; 2010

LAZEN, Latin American Zebrafish Network

Regeneration and growth that occur in the adult teleost retina have been helpful in identifying molecular and cellular mechanisms underlying cell proliferation and differentiation. Eyes in fish grow throughout life and the retina matches this growth by stretching and the continuous differentiation of new cells. Genesis of retinal cells, except rod photoreceptors, occurs in a germinal neuroepithelium at the periphery of the neural retina, the ciliary marginal zone (CMZ). Rod photoreceptors differentiate from precursor cells embedded in the outer nuclear layer (ONL) within the mature retina. In teleost fish, damage of the mature retina activates repair mechanisms and regenerated neurons arise from intrinsic germinal cells. There are different pools of putative progenitors: pax6-expressing stem cells at the inner nuclear layer-inner plexiform layer (INL–IPL) border, proliferative cell clusters in the INL, and a subset of Müller glia reentering the cell cycle following injury to produce neuronal progenitors. In the developing vertebrate retina as well as in the dynamic retina of adult teleost fish, a coordinated balance of progenitor cell proliferation and cell-cycle exit is critical for the generation of a functional neural and glial network. Among several cues controlling these processes, purinergic signaling has a major role in regulating cell-cycle activity in early stages of the developing vertebrate retina.