Fig. 2. Ovaries of TrkC^–/– mice contain normal numbers of follicles but those of TrkB^–/– mice contain few follicles. This phenomenon is found in 50% of TrkB^–/– mice on either the mixed genetic background or the 129/Sv congenic line, but all ovaries in the C57BL/6 congenic line are affected. Scattergram of number of oocytes in ovaries of TrkB^+/+,TrkC^+/+ mice (column 1); TrkC^–/– mice (column 2); TrkB^–/– mice from the original mixed genetic background colony (column 3); TrkB^–/– mice from the 129/Sv congenic colony (column 4); and TrkB^–/– mice from the C57BL/6 colony (column 5). In column 1, TrkB^+/+, TrkC^+/+ mouse on C57BL/6 background is represented with a filled square and those on 129/Sv background are represented with open triangles, other mice are of the mixed genetic background. In column 5, filled diamonds represent mice from the seventh generation of the C57BL/6 congenic line of TrkB^–/– mice and crosses are mice from the fourth generation.