Distribution and Density of Medium- and Short-wavelength Selective Cones in the Domestic Pig Retina

• Published in: Experimental Eye Research Vol. 74; no. 4; pp. 435 - 444
• Main Authors: Hendrickson, Anita, Hicks, David
• Format: Book Review Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2002
• Subjects: Animals; Arrestin - analysis; immunocytochemistry; Models, Animal; opsin; photoreceptor; Retinal Cone Photoreceptor Cells - anatomy & histology; Retinal Cone Photoreceptor Cells - chemistry; Rod Opsins - analysis; Swine - anatomy & histology; Transducin - analysis; immunocytochemistry; opsin; photoreceptor
• ISSN: 0014-4835; 1096-0007
• DOI: 10.1006/exer.2002.1181

The topography of medium (M)- and short (S)-wavelength sensitive cone photoreceptors was studied in the domestic pig retina. Antisera specific for M or S opsin as well as cone photoreceptor proteins arrestin and alpha-transducin were used to label cone types. Retinal wholemounts and their blood vessel patterns were drawn and specific regions removed. The wholemounts were immunocytochemically labelled to detect both M and S cones, and the specific regions labelled to detect S cones. Cones were counted in a 1mm grid pattern, using the drawings as a guide. Pig retina has a high cone density retinal streak extending across the retina covering the optic disc (OD) and horizontal meridian. Densities in the streak are 20000–35000mm−2. Two higher peaks occur in the streak, one in temporal retina near the OD (39000mm−2) and the other in nasal retina 5–7mm from the OD (40500mm−2). The lowest cone density is in far peripheral inferior retina (7000mm−2). The total number of cones in pig retina is 17–20 million. Both types of cones are found throughout the retina, with S cone percentages ranging from 7.4 to 17.5% in no consistent topographical pattern. S cones have an irregular local distribution which can vary from a regular hexagonal pattern to small clusters of adjacent S cones to small areas lacking S cones. Double-label immunocytochemistry found that virtually all S cone outer segments (OS) contain some M opsin. M cone OS do not label at detectible levels for S opsin. Domestic pig retina is widely available, large, has a high cone density and has two types of cones. This tissue should be an excellent source for biochemical analysis of cone proteins, and for in vitro approaches to understanding cone survival factors.