Because one X chromosome is inactivated at random in each cell during a woman's development, deuteranomalous heterozygotes (. female carriers of deuteranomaly) are potentially tetrachromats , because they will have the normal long wave (red) receptors, the normal medium wave (green) receptors, the abnormal medium wave (deuteranomalous) receptors and the normal autosomal short wave (blue) receptors in their retinas.    The same applies to the carriers of protanomaly (who have two types of short wave receptors, normal medium wave receptors, and normal autosomal short wave receptors in their retinas). If, by chance, a woman is heterozygous for both protanomaly and deuteranomaly she could be pentachromatic. This situation could arise if, for instance, she inherited the X chromosome with the abnormal long wave gene (but normal medium wave gene) from her mother who is a carrier of protanomaly, and her other X chromosome from a deuteranomalous father. Such a woman would have a normal and an abnormal long wave receptor, a normal and abnormal medium wave receptor, and a normal autosomal short wave receptor – 5 different types of color receptors in all. The degree to which women who are carriers of either protanomaly or deuteranomaly are demonstrably tetrachromatic and require a mixture of four spectral lights to match an arbitrary light is very variable. In many cases it is almost unnoticeable, but in a minority the tetrachromacy is very outspoken.    However, Jameson et al .  have shown that with appropriate and sufficiently sensitive equipment all female carriers of red-green color blindness (. heterozygous protanomaly, or heterozygous deuteranomaly) are tetrachromats to a greater or lesser extent.