| Research Abstract |
Normal human anagen hair appartuses of Caucasian, Negro and Japanese individuals were morphologically studied using Transmission Electron Microscope (TEM). The hair cortical cells of these hair apparatuses were found to produce small,electron dense granules surrounded by ribosomes in the cytoplasm within the about 150um range of the keratogenous zone. These granules fused to tonofilaments and were named "cortical trichohyaline granules." The Inner-Most Cells (IMCs) of the outer root sheath generated as an independent single cell layer in the hair bulb. They formed transversely running tonofilaments in the Henle's side of the cytoplasm at the middle level of the hair follicle. The IMCs seemed to play a role to support and cover the inner hair structures, tightly as hoops of a barrel. Individual cell layers in hair apparatus revealed its own characteristic cytological features during the cell differentiation ; the production or formation of cell structures, such as tonofilaments, interfi
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lamentous substances, lamellar bodies and marginal bands, was significantly different in degrees among the layers. Between different races, melanocytes in the hair bulbs produced morphologically different types of melanosomes as well known. Furthermore, Caucasian and Japanese hair follicles showed straight or slightly curved shapes, whereas Negro ones showed an extremely curved shape ; this morphological difference seemed to be caused by a structural difference of the connective tissue sheath between different races.
Human hair keratins are composed of Hair Fibrous Proteins (HFP) and nonfilamentous cysteine-rich Hair Matrix Proteins (HMP) ; these proteins are highly cross-linked by disulfide bonds. In order to obtain high-resolutional separation of HFP and HMP by twoーdimensional polyacrylamide gel electrophoresis (2D-PAGE) according to isoelectric point (IP) in the first dimension and molecular weight (MW) in the second dimension, these proteins were converted to S-carbamoylmethyl derivatives with nonionizable iodoーacetamide ; this treatment made little modification of electrophoretic mobilities. S-carbamoylmethylated (SCam)-HFP were separated into polypeptides with MW 41.5k-59k (IP ph 5.1-6.8). SCam-HMP were subdivided into two groups ; 14 polypeptides of acidic HMP with MW 15k-28k (IP pH 5.0-7.0) and 12 polypeptides of basic HMP with MW 18.5kー28k (IP pH 7.8-8.8). Variation in electrophoretic patterns among hair samples obtained from 15 persons in 4 Japanese families was found in acidic HMP, but neither in HFP nor in basic HMP.
By Scanning Electron Microscope (SEM), the plucked hairs of monilethrix showed a typical moniliform feature composed of alternated nodes and internodes. By TEM of biopsied hair apparatuses, a marked degeneration of hair matrix cells was found and a zigーzag disarray of cortical tonofibrils and invaginations of the hair cuticle cells into the cortex were noticed in the suprabulbar portion. In some hairs, the hair bulbs showed no degeneration, but a degeneration of cortical cells and invaginations of hair cuticle were seen in some portions in the developing zone of the cortex. In all the hair apparatuses examined, cytoplasmic vacuolations were always seen in the various layers and abnormal formation of tonofibrils was often observed in the cortex. In monilethrix, periodical cell degeneration seemed to result in the periodical decrease in number of cortical cells and periodical thinning of tte hair shaft. On the other hand, by SEM, invaginations of hair cuticle layer into the cortex were found to occur in trichorrhexis invaginata (bamboo hair). By TEM, the invaginations were considered to be caused by a softness of the keratinizing cortical cells. Since no cell degeneration occurred and the number of cortical cells was not decreased, the hair shaft of bamboo hair was swollen around the invaginations. In pili annulati, a slight degree of undulations of the hair surface were seen by SEM ; this might be caused by lacking in a homogeneity of the keratinizing cortex. Namely, by TEM, a number of empty spaces were formed in the cortex and the cortex lost a compact structure filled with keratins. The empty spaces of the cortex in pili annulati were not formed by a cell degeneration in the hair matrix, but by a remarkably decreased production of tonofibrils of developing cortical cells. All of three hair disorders, i. e., monilethrix, trichorrhexis invaginata and pili annulati, were regarded as inherited hair disorders, in which the cortical cells were mainly affected, although the mechanisms were different in each disorder. Biochemically, by PAGE, the extracted HFP from a hair sample of trichorrhexis invaginata showed no abnormal finding. By 2D-PAGE, the hair samples of acquired trichorrhexis nodosa cases revealed normal electrophoretic patterns of polypeptides of HFP, acidic HMP and basic HMP, whereas the acidic HMP of a pili torti hair sample was found to be very low in proportional amount, although its HFP and basic HMP were normal in electrophoretic pattern. The combination of morphological surveys by SEM and TEM, and biochemical surveys by 2D-PAGE is considered to be very useful for pathological studies of various hair disorders. Less
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