Table 1.
Number of Neurons in DRGs of Normal and Mutant Mice during Embryonic Development
| Mice | E10 | E11 | E12 | E13 | E15 | E17 | P0 | |
|---|---|---|---|---|---|---|---|---|
| T1 | +/+ | 720 ± 252 (2) | 1669 ± 174 (5) | 2123 ± 198 (4) | 4599 ± 219 (3) | 4729 ± 140 (7) | 4913 ± 155 (4) | 5583 ± 167 (4) |
| −/− | 638 ± 140 (3)n | 921 ± 114 (4)b | 1864 ± 205 (4)n | 2152 ± 58 (4)c | 2004 ± 113 (9)c | 1825 ± 269 (4)c | 1588 ± 48 (2)c | |
| T6 | +/+ | 298 ± 2 (2) | 1385 ± 113 (3) | 1680 ± 62 (5) | 3373 ± 98 (3) | 2988 ± 178 (4) | ND | ND |
| −/− | 320 ± 56 (2)n | 723 ± 25 (3)b | 1986 ± 113 (4)n | 2066 ± 141 (4)c | 1769 ± 130 (4)b | ND | ND | |
| L1 | +/+ | NG | 2109 ± 150 (3) | 2506 ± 299 (5) | 4808 ± 192 (3) | 5444 ± 264 (8) | 5595 ± 490 (6) | 5189 ± 286 (3) |
| −/− | NG | 1378 ± 154 (2)a | 2309 ± 256 (3)n | 2277 ± 184 (4)c | 2241 ± 134 (9)c | 2449 ± 182 (5)c | 2236 ± 257 (3)b | |
| L4 | +/+ | NG | 2592 ± 24 (2) | 2816 ± 449 (5) | 6830 ± 343 (3) | 6332 ± 607 (3) | ND | 5745 ± 530 (3) |
| −/− | NG | 1676 ± 44 (2)b | 2883 ± 415 (3)n | 2691 ± 264 (4)b | 1848 ± 325 (3)b | ND | 1530 ± 378 (2)a | |
Numbers of neurons were counted in four different DRGs: thoracic 1 (T1), thoracic 6 (T6), lumbar 1 (L1), and lumbar 4 (L4) of wild-type (+/+) and mutant (−/−) mice at the indicated embryonic (E) or postnatal (P) stages. Between E10 and E13, the number of neurons was calculated by counting the number of neurofilament-positive cells present in each ganglion. After E15, neurons were quantitated in Nissl stained sections. At E15, the number of DRG neurons was obtained in both Nissl stained embryos and embryos stained for neurofilament. Because both determinations yielded identical numbers, they have been pooled together in the table. Numbers are expressed as mean ± SEM. The numbers in parenthesis indicate the number of individual embryos analyzed in each case. Abbreviations, ND, not determined; NG, no discernible ganglia. Differences between the two genotypes were tested using a one-way Student’s t-test.
p < 0.01,
p < 0.005,
p < 0.001,
not significant. Notice that there are significantly fewer neurons at E11 in each ganglion in mutant vs. wild-type animals, but there are no statistically significant differences at E12.