Microscopic structure of smooth and keeled scales in snakes

The figures below illustrate the microscopic structure of some keeled and smooth scales. The images are magnified 2000-5000x.
Keeled scale (Pinou)
Rough Green Snake
Opheodrys aestivus
Smooth scale (Pinou)
Smooth Green Snake
Liochlorophis vernalis
AKA Opheodrys vernalis
Keeled scale (Smith, et al.)
Northern Water Snake
Nerodia sipedon
Smooth scale (Smith, et al.)
Pipe Snake / False Coral Snake
Anilius scytale


References: Thanks to the individuals below for allowing the reproduction of their photomicrographs on this site.
Theodora Pinou. Snake scale microdermatoglyphics.
From: http://pantheon.yale.edu/%7Etp36/research.htm
Hobart Smith, et al. The function of squamate epidermatoglyphics.
From: http://herpetology.com/1phs30.html
Published in: Bulletin of the Philadelphia Herpetological Society, Vol. 30 (1982) and Vol. 31 (1983-4 photos)