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Fig. 4. (A) Photomicrograph of the mid-band region of the cornea. `High PS cells'
are found within rows 2D, 5 and 6. (B) 7 µm frontal section through the
retina showing a dye-filled R8 cell of the dorsal hemisphere (DH) and a R6
cell of row 2D. (C) Diagrams of the arrangement of retinula cells R1-R7 in
rows 2D, 5 and 6 in a right eye (frontal view). Group I retinula cells are
stippled and Group II retinula cells are plain. Note that the cell arrangement
in row 6 is twisted 90° counterclockwise compared to row 5 as identified
by the R8 axon position, the dark spot. (D) Preferred e-vector orientations
(
max) of the two retinula cell groups (Group I and Group II).
The max of the two cell groups are perpendicular and coincide
with the microvillar orientations within the corresponding photoreceptors. Row
2D (distal rhabdomal tier) is formed by only four retinula cells, which are
also divided into two cell groups sensitive to orthogonal max
(R2, R6 and R3, R7). See Marshall et al.
(Marshall et al., 1991a) for
anatomical details.
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