Figure 1

Uninjured and regenerating stages of the radial nerve cord (RNC) of H. glaberrima. Longitudinal tissue sections of (A) uninjured and regenerating RNC at (B) 2, (C) 6, (D) 12, (E) 20 and (F) 28 days post injury (dpi) were stained with Toluidene Blue. (A) The uninjured RNC clearly shows the large ectoneural (EN) component separated from the thinner hyponeural (HN) component by a connective tissue band. (B) At 2 dpi the area is filled with debris and the open end of the RNC is visible (arrowhead). (C) By 6 dpi, the RNC stumps have organized into club-shaped structures. (D) By 12 dpi the injury gap has been filled with nervous tissue that now forms a continuous extension that joins the stumps. (E) By 20 dpi the RNC still appears slightly disorganized and no connective tissue band is observed. (F) At 28 dpi, the RNC has recovered much of the structure and organization found within non-injured RNC including the separation between the EN and HN components by a connective tissue band. D-dermis, EN-epineural component, HN-hyponeural component, RNC-radial nerve cord. X's denote the injury site; Asterisks show the presence of tattoo ink used to label the injury site; arrows signal morula cells within the RNC. Bar = 300 μm.