Chapter 14 475 and its sulfate and ceramides originate from the hair matrix cells. Masukawa et al. have also concluded with others that 18-methyl eicosanoic acid (18-MEA) also originates from the matrix cells. On the other hand, these scientists concluded that although some fatty acids likely originate from hair matrix cells, most fatty acids, triglycerides, wax esters and squalene originate from the sebaceous glands, but the source of the hydrocarbons is not known at this time. Masukawa et al. and Wertz and Downing48 have described the different lipid types and levels in adult hair. The results of these studies are summarized in Table 9. Table 9. Lipids in human hair from Masukawa et al.47 and Wertz and Downing48 Source Type of lipid mg/gm hair A Squalene 0.7 A Wax esters 4.9 A Triglycerides 0.5 A Total fatty acids 14.4 B Cholesterol 1.3 (0.6)* B Cholesterol sulfate n/a (2.9)* B Ceramides 0.29 (0.5)* B Covalent fatty acids n/a (4.0)* B 18-MEA 0.30 (1.6)* C Hydrocarbons 2.4 TOTALS 24.79 *Data in parenthesis by Wertz and Downing,48,49 not in parenthesis by Masukawa et al.47 Masukawa et al. isolated lipids from the root sections of the hair of 44 Japanese females varying in age 1–81 years. Wertz and Downing48 examined four different Caucasian hu- man hair samples (three from individuals and one pooled hair sample of presumably Caucasian hair). In another paper Wertz and Downing49 cited 4.3 mg/gm total integral (covalently bound) fatty acids with 40.5% as 18-MEA for human hair, or 1.7mg/gm 18-MEA (hair from three individuals and one pooled hair sample). Of the different types of lipids found in human hair described in Table 9, those labeled “A” originate primarily from sebaceous glands and those labeled “B” originate mainly from hair matrix