Hello,

I am working on a study of iris pigmentation and relational cell size to other anterior pigmented cell structures in humans. This may be a "hail mary" but is there anyone that would happen to have a resonable average measurement (eg. diameter, circumferance, measurement or cells per square micron?

I appreciate any input or direction you could contribute.

Thanks,

Daniel Streibig

Danstreibig@hotmail.com

-- Daniel Streibig (danstreibig@hotmail.com), May 30, 2001

Answers

Dan,

pigment granules in the iris tend to range from 100 to 600 nm.

see Table 2: http://www.milesresearch.com/iris/eagle/eagletable2.htm

and the other tables and pics at http://www.milesresearch.com/iris/index.htm

Iris Ultrastructure Table 1 Iris Ultrastructure Table 2 Iris Ultrastructure Table 3 Iris Ultrastructure Table 4 Iris Ultrastructure Table 5

Table 1 shows the cellularity of the Anterior Border Layer for different eye colors, ranging from 29/field in blue iris to 18/field in brown iris (a field is 5500 square microns).

Table 3 shows the Melanin granule prevalance by iris color, and the data is ranging from 7.5 granules (0.4 sq um) in blue to 441 granules (67 sq um) per field; the dark brown nevus has 484 granules/5500 sq um or 131 sq um/5500 sq um field density.

The big difference in color is due to both size and number of granules per cell rather than the number of cells.

The info you need can be found in:

Iris Pigmentation and Pigmented Lesions: An Ultrastructural Study by Ralph C. Eagle, Jr., M.D. Department of Pathology, Wills Eye Hospital, Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania.

British Journal of Ophthalmology 70:581-687 (monograph)

--Jon Miles

-- Jon Miles (jon@milesresearch.com), May 31, 2001.

Hi, Dan,

Now I know where to reach you. I don't have an answer to your question, but my eyes are looking down the highway for the impending visit from your mother and dad in two weeks.

Hope life treats you as well as it treats me, which is very good.

Uncle Don

-- Donald R. Streibig (STREIBIGD@AOL.COM), September 08, 2001.