John,
The eye is made up of a wide variety of types of tissues, from hard  dense
lenses to heat sensitive optic nerve fibers, all housed in a tough scleral
shell. With the room temperature waterbath you can position the globe on the
slide  with the nerve tissue closest to the "label" end ,where it will
encounter the least amount of exposure to hot water, and the cornea on the
far end of the slide where it will spend the longest time in warm water. The
"hot" water bath will need to be a bit warmer than your normal temperature
to facilitate stretching of the cornea and sclera as well as helping the
lens adhere to the glass, I often used above 50C temp.
When you dip the  slide in the warm bath you use a 45 degree angle and  keep
the corner of the section  adhered to the glass so that the rest of the
section floats out on the water and the surface tension helps to stretch the
wrinkles out along with the heat. 
All that said, you can certainly float the eye directly on to a warm
waterbath but  you may get scleral wrinkling and/or optic nerve "blow out".
After many years in Eye Pathology I have been working in Cardiovascular
Research and adopted the dual waterbath for our projects where we need
optimal stretching and minimal distortion of vessels for morphometry. They
were a bit skeptical, but have loved the results:)
Mary Georger
Center for Cardiovascular Research
University of Rochester Medical Center
KMRB Room 2-9816
601 Elmwood Avenue.
PO Box 679
Rochester, New York  14642
585-273-1548

> ----------
> From: 	Demirs, John T.
> Sent: 	Wednesday, February 12, 2003 12:03 PM
> To: 	Histo Net (E-mail)
> Subject: 	Eye microtomy
> 
> I have read that when sectioning eyes for histology that you first place
> the
> ribbon onto a cold water bath then onto a warm water bath. This is not
> done
> for any other tissue type.  
> 
> Why then is it done for Eyes, and is it necessary? 
> 
> Can you go directly to the warm water bath with out adverse effects.
> 
> jdemirs@partners.org
> jdemirs@helix.mgh.harvard.edu
> 
> 
> John T. Demirs B. A. HTL (ASCP)
> Wellman Laboratories of Photomedicine
> Massachusetts General Hospital
> Photopathology Dept. Edward 214
> 15 Fruit St.
> Boston Ma 02114
> 617-726-6984 phone
> 617-726-1206 fax
> 
> 
>