Retina, choroid, in tapetal region, normal

Source 6 year castrated male hunter pony
Fixative glutaraldehyde
Stain azure II-methylene blue
Notes Although not an ideal image, this nicely illustrates the marked thickness of the choroid relative to the retina in this species (notice that not all the choroid is visible, yet it is as thick or thicker than the retina); also illustrated is the histologic correlate of the ophthalmoscopic Stars of Winslow (the hole in the tapetum caused by capillaries going from the choroid proper to form the choriocapillaris; if you display the larger image, you can see the opening on the retinal epithelial side more easily)
See also
Legend arrowhead - choriocapillaris, arrow - capillary perforating tapetum, C - choroid, N - nerve fiber layer, O - photoreceptor perikarya (outer nuclear layer), T - tapetum
Illustration Click on image to see larger picture
s-1969p.jpg