Pigmentation in horses refers to the coloration of their coat, skin, and eyes, which results from the distribution and concentration of pigments such as melanin. This pigmentation is determined by genetic factors, influencing a horse's appearance and ability to adapt to environmental conditions. Common pigments include eumelanin, responsible for black and brown colors, and pheomelanin, which produces red and yellow hues. Variations in pigmentation can be indicators of genetic diversity and are studied in relation to breed characteristics and inheritance patterns. This page compiles peer-reviewed research studies and scholarly articles that explore the genetic mechanisms, variations, and implications of pigmentation in equine species.
Cozzi B, Ferrandi B.The horse pineal gland has been investigated by morphological and histochemical methods. Particular care has been given to the cellular types, to the eventual presence of neurosecretory activity and to the nature of the pigments. Even in the horse pineal, it is possible to distinguish two populations of pinealocytes, morphologically but not histochemically distinct. A great number of pinealocytes are positive for the Masson- Hamperl reaction, and for Gomori- Bargmann 's chromic haematoxylin-phloxine and Gomori's paraldehyde-fuchsin. Along the connective septa, many brown- blackish pigmented ce...
Wouters L, De Moor A.An electron microscopic description was given of the pigment epithelium and the photoreceptors of the horse retina. Duplicity (rods-cones) of the horse retina was proven histologically; the retina was classified as an "E" retina, which indicates predominance of the rod system.
The Journal of heredityMarch 1, 1988
Volume 79, Issue 2 100-106 doi: 10.1093/oxfordjournals.jhered.a110461
Woolf CM, Swafford JR.The ultrastructural imaging of melanocytes coupled with analyses to detect sulfur-containing melanosomes by energy-dispersive X-ray spectroscopy were used to test the hypothesis that the yellowish-red and black pigments found in Arabian horses result from pheomelanogenesis and eumelanogenesis, respectively. These procedures detected pheomelanosomes in follicles at the base of hairs in chestnut horses and eumelanosomes in follicles at the base of hairs in black horses. By analyzing tissue obtained by skin biopsy, these procedures also demonstrated that skin melanocytes in a chestnut horse produ...
Altmeyer P, Holzmann H, Stöhr L, Koch HJ.White horses are subject to age-dependent coat depigmentation. They are dark gray or black at birth and lose their coloring between their second and fourth year. Beginning at about age 10 their coat takes on a characteristic silver-gray coloring. The purpose of this paper was to find out to what extent the endogenic alpha-MSH level changes with the change in pigmentation. alpha-MSH plasma levels were determined by radioimmunologic analysis in 3 age groups of white Camarque horses: age group 1 consisted of dark horses with a mean age of 1.2 years and a mean alpha-MSH level of 106.4 pg/ml +/- 18...
Murabayashi H, Hondo E, Kitamura N, Furuoka H, Taguchi K, Nambo Y, Yamada J.One of the most attractive characteristics of a horse testis is the change of the weight during development. As the testicular weight changes and the number of Leydig cells decreases, pigments appear in interstitial tissues. In the present study, the characteristics of the pigments found in the interstitial tissues were examined histochemically and ultrastructurally. Specific stainings indicated that the pigmented granules showed almost all of the histological and histochemical characteristics of ceroid or ceroid-like pigment. The cells showed positive reaction for acid phosphatase while the p...
Gossett CL, Guyer D, Hein J, Brooks SA.White spotting is an iconic feature of the American Paint Horse. The American Paint Horse Association (APHA) is dedicated to recording pedigree and performance of this stock-type breed, while preserving its distinctive coat color and conformation. Here, the depigmented proportion of the coat (% white coat) was measured using digital photograph analysis of 1195 registered American Paint Horses. Genotypes for nine white-spotting polymorphisms commonly found in Paint Horses, and two pigment-producing loci and genes, were also provided by the APHA. White-coat percent significantly increased in h...
