In the 1930s a group of Japanese researchers led by Dr. W. Nakahara isolated two distinct factors that were reported to be essential for lactation in the rat. They coined the term "Vitamin L" for these factors and proposed that they were essential for proper metabolism in humans. Subsequent studies indicated that factor L(1), extracted from bovine (calf) liver, was anthranilic acid. The second factor, L(2), was extracted from yeast and shown to be adenylthiomethylpentose. Later studies have confirmed that neither of these factors are essential to lactation either in rats or in humans. There are no proven symptoms from dietary deficiencies of either of these biochemicals.

Polarized light images were captured using an Intel Play QX3 computer microscope modified for crossed polarized illumination. Additional light was applied to the specimens using light pipes from a Dolan-Jenner Model 180 fiber optics illuminator containing a 150 watt projection lamp. A 5/16-inch hole was drilled into the light mixing chamber at the base of the microscope and the light pipe was pointed towards the far wall of the chamber to increase illumination.

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