A. At II2, labeling is present in the optic lobe anlagen, which contain populations of neuroblasts undergoing symmetrical divisions (black arrows). Inset shows a higher magnification view of the cytoplasmic staining observed in cells of the optic lobe anlagen. The olfactory proliferation center and some other scattered cells were also labeled (white arrowheads). The midline of the brain is at the left of the panel.
B. A higher magnification view of the optic lobe anlagen at III2. Black arrow indicates the outer optic lobe anlagen. The labeling in the cortical cytoplasm of neuroblasts in the outer layer is intense, but diffusely distributed throughout the cytoplasm (double white arrowhead). Perinuclear staining is also present (single white arrowheads).
C. At V0, the inner optic lobe anlagen is separated from the outer optic lobe anlagen by the newly formed medulla cortex (MCo), which displays only background levels of immunostaining. Black arrowheads indicate the neuroblasts of the inner optic lobe anlagen. The position of the unlabeled optic nerve (ON) is indicated. The midline of the brain (not shown) is at the left of the panel.
D. At W0, the outer optic lobe anlagen (black arrow) and inner optic lobe anlagen (black arrowhead) are further separated from each other. Neuroblasts and GMCs are immunopositive for P1G11 in the proliferation centers (white arrowheads).
A, C, and D are frontal sections; B is a horizontal section. Scale bars: (A, C, D) 50 µm (for inset in A: 20 µm); (B) 20 µm.