title: The cell cycle during amphibian limb regeneration.
abstract: The duration of the cell cycle in the blastema of regenerating limbs of axolotls has been measured by means of [3H]thymidine pulse labelling and autoradiography. A chase was required to define the pulse period. An average cell cycle at 20 degrees C takes 53 h, S-phase takes 38 h; including parts of mitosis, G1 is 10 h and G2 is 5 h long. The protracted cycle and S-phase are consonant with the large genome in axolotis and other urodeles. The rapidly growing blastema probably contains a steady population of about 5000 proliferating cells, as there is a regular withdrawal of differentiating cells from the population. The kinds of determination which exist in this population of cells, or are exerted on it, are briefly considered.
mesh_terms: D000557:Ambystoma / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D005121:Extremities / Q000502:physiology*; D008938:Mitosis; D012038:Regeneration; D013936:Thymidine / Q000378:metabolism
chemical_list: D013936:Thymidine