Regeneration

Nota:

• stem cells regrow tissue/organs

1. stem cells regrow tissue/organs

Nota:

• dedifferentiation--redifferentiation (new structure)

1. Salamander limb
   1. amputated
      1. plasma clot

         Nota:

         • 6-12 hours
         1. wound epidermis
            1. ECM degraded
               1. cell dedifferentiation

                  Nota:

                  • bone cells cartilage cells fibroblasts myocytes
                  1. regeneration blastema

                     Nota:

                     • proliferate-- nAG -eventually redifferentiate-restricted progenetor cells-bone cells-cartilage cells-fibroblasts-myocytes
                     1. V-ATPase proton (H+) pump

                        Nota:

                        • no pump= no regeneration
            2. apical epidermal cap (AEC)

               Nota:

               • wound epidermis thickens
               1. Fgf8

                  Nota:

                  • secretes Fgf8 if nerves present
2. dedifferentiation
   1. redifferentiation

Nota:

• -repatterning of existing tissue -little new growth

1. Hydra
   1. basal disc (foot)
      1. foot activation gradient
      2. foot inibition gradient
      3. shinguard

         Nota:

         • -just above basal disc -buds appear where Shinguard fades
   2. hypostome (mouth/tentacles)
      1. head activation gradient
         1. peptides
            1. head formation
               1. Heady
               2. Head
            2. tentacles
               1. Hym301
      2. head inhibitor
      3. "organizer"

         Nota:

         • -when transplanted can induce formation of 2nd axis -head actvation & inhibition signals -"self-differentiating" -inhibition signal inhibits formation of new organizing centers
         1. Wnt

            Nota:

            • form head organizer
         2. Goosecoid
         3. Brachyury

            Nota:

            • head & body boundary

Nota:

• -differentiated cells divide -cell makes cell similar to itself - ie: mammalian liver

1. mammalian liver
2. differentiated cells divide