PENETRATION INTO HAIR FIBER 269 Figure 3. Pretreatment with aqueous silver nitrate, after which the hair was rinsed, dried, and exposed to light. Note the extensive silver deposits in the cortical membranes (•,•). There are pigment granules ((in) but no apparent contrast in the macrofibrils. Scale bar = 0.3 lain. 5(i). cortex were intensely stained, revealing a typical microfibril/matrix ultrastructure. Localized deposits of silver were seen within the cell membrane complex of the cortex and within some inter-macrofibrillar material. For hair immersed in sodium chloride (two minutes), dried, followed by immer-

270 JOURNAL OF COSMETIC SCIENCE / j Figure 4. Hair fiber pretreated with aqueous silver nitrate, then made alkaline with sodium hydroxide. Intense staining of the sulphur-rich domains (D) shows penetration of silver and hydroxide throughout the cuticle and cortex. Deposits of silver are present in the cuticle cell membrane complex (4-,•). Scale bar = 0.5 !•m. sion in aqueous silver nitrate (two minutes), and then exposed to light, fine deposits were observed within the cell membrane complex of some, but not all, cuticle cells. Adjacent to these deposits and within the a-layer and exocuticle were "cascade-like" deposits of silver (Figures 6, 7). Fine, disperse deposits were ob-

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