Figure 7.

Absence of SARS-CoV-2 invasion of the parenchyma of the frontal lobe

(A) Schematic of a cross section through a blood vessel.

(B–L) Confocal images of sections through frontal lobe samples of control cases (B and C) and COVID cases (D–L).

(B) TJP1-IR stripes label tight junctions among endothelial cells of a cerebral blood vessel.

(C) PECAM1 puncta label endothelial cells of a blood vessel and AQP4-IR signal labels the endfeet of astrocytes forming the glia limitans perivascularis. The unstained, dark ring between the area with PECAM1 puncta and the AQP4-IR ring is the VRS.

(D and E) In COVID #60 (non-variant of concern), N puncta occur within the lumen of a blood vessel filled with red blood cells (D). A swarm of N puncta appears to have burst through the endothelial layer of a blood vessel (E). Endothelial cells harbor PECAM1 puncta and contain CD31-IR signal.

(F and G) In COVID #87 (Delta), N puncta are dispersed intravascularly (F) and perivascularly (G). The white dots in the parenchyma represent autofluorescence signal from lipofuscin, emitting in all channels.

(H) In COVID #89 (Delta), N puncta occur within the lumen of a blood vessel filled with red blood cells but not beyond the AQP4-IR ring.

(I) In COVID #110 (Omicron BA.1), N puncta occur perivascularly but not beyond the AQP4-IR ring.

(J–L) In COVID #108 (Omicron BA.1), puffs of N puncta (J and L) or S puncta (K) appear to have leaked through a blood vessel wall identified with PECAM1 puncta (J–L), TJP1-IR signal (J), or CD31-IR signal (K). Viral puncta have not penetrated into the parenchyma (L).