A morphological study of the development of the leptomeninx of the fetal rabbit cerebrum

The development of the leptomeninx of the rabbit cerebrum is similar to that of the rabbit spinal cord. At E12 and E14 the leptomeningeal cells resemble immature fibroblasts. At E16 glycogen granules appear in the leptomeningeal cell cytoplasm and are present in pial as well as arachnoid cells. The amount of glycogen decreases from E22 until by E28 it is rarely found in leptomeningeal cells. Leptomeningeal macrophages are present from E12 but granular pial cells were not observed prior to E16. Initially collagen in the pial layer consists of scattered fine fibrils but by E20 collagen is present in larger amounts and the fibrils are of larger diameter and banded.