GW 37
CERVICAL
ENLARGEMENTTHORACICLUMBARENLARGEMENTSACRAL4-DAY-OLD INFANT 4-MONTH-OLD INFANT
See Plate 65See Plate 69See Plate 80See Plate 84See Plate 106See Plate 110See Plate 75 See Plate 88 See Plate 116See Plate 77 See Plate 9037.75%
62.12%
CC .05% EP .09%25.50%
74.34%
CC .05% EP .11%34.83%
65.10%
CC .01% EP .06%30.88%
69.04%
CC .04% EP .05%25.32%
74.61%
CC .01% EP .06%18.56%
81.37%
CC .03% EP .04%45.50% 54.40%
CC .04% EP .07%65.93%
33.96%
CC .02% EP .09%55.94%
43.95%
CC .06% EP .06%66.11%
33.57%
CC .08% EP .25%67.61%
31.93%
CC .06% EP .40%CENTRAL CANAL (CC)WHITE MATTERGRAY MATTEREPENDYMA (EP)Figure 37. A continuation of the previous fi gure in specimens at GW37 (column 1, Y117–61), a 4-day-old infant (column 2, Y299–62), and a 4-month-
old infant (column 3, Y23–60). A section at the sacral level is not available in the 4-month-old infant. The roof and fl oor plates are absent at these
ages, and the proportional areas of the central canal and ependyma appear on the graphs as slightly thicker black lines separating the gray matter and
white matter at the 12:00 position in each chart. The smaller proportional areas of the white matter at the sacral level perinatally (bottom row, fi rst two
columns) indicate immature white matter. In contrast, the cervical enlargement (row1) and thoracic levels (row 2) have high to very high proportions
of white matter to gray matter indicating that the white matter is quite mature in all these specimens. The very high proportion of white matter at the
thoracic level is because the ventral horn is quite small at these levels, just as it is in the adult spinal cord. At the ages shown here, the lower proportional
area of white matter at the lumbar enlargement (row 3) does not indicate immaturity. That is because all axons from the brain that terminate at lumbar
and sacral levels pass through cervical and thoracic parts, increasing the proportional area of the white matter at those levels.
Level Differences in Proportional Areas: GW37-4th Month FIGURE 37