Figure 3.

Light micrographs showing the localisation of BED in neocortex of opossums at P2 (A) and P5 (B–F) 20–25min after an intraperitoneal injection. A–C are vibratome sections (50µm) and D–F semithin sections (0.5µm).

A) Note that at P2 there are no vessels present in the neocortex except for occasional one in the most lateral more developed parts (*).

B) At P5 a few vessels are present within the neocortex. Note also that the staining of BED is most abundant in outer and inner surfaces of the cortex and in the choroid plexus (ch).

C) High power micrograph showing vessels (paired vessels are characteristic of marsupial brains) growing into the neocortex. Note that the staining for BED is most visible within the vessels, in the marginal and subplate zones, similar to the staining for BDA3000 (see 4A).

D) Section of the whole neocortex counterstained with toluidine blue. This section shows that in the cortex the reaction product is most visible within the marginal and the subplate zones (shown in high power in E). Note also how few vessels are visible in the neocortex at this age (one pair in lower box and shown at high power in F).

E) Higher power view of upper box in D. Note reaction product in marginal zone (mz) and subplate zone (sp) indicated by *.

F) Higher power magnification of two paired blood vessels from lower box in D showing that at the light microscopic level it appears that only the lumen of the vessels is stained and no reaction product is visible in the extracellular space surrounding the vessels.

Scale bars are 100µm in A&B, 50µm in C, 100µm in D, 50µm in E and 20µm in F. Abbreviations: LV – lateral ventricle, mz – marginal zone, cp – cortical plate, sp - subplate, vz – ventricular zone.