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The Healing of Skin Wounds in Primates
Vol. 50, No. 4
THE JOURNAL OF INYESTIOATIYE DERMATOLOGY
Copyright
Printed in U.S.A.
1968 by The Williams & Wilkins Co.
THE HEALING OF SKIN WOUNDS IN PRIMATES II. THE PEOLIFEnATION OF EPIDEILMAL CELL MELANOCYTES*
LUIGI GIACOMETTI, PH.D. AND WILLIAM MONTAGNA, Pn.D.
In this short report we will show that epi- wounds that are relevant to proliferation of dermal melanoeytes are capable of proliferat- melanocytes. Bleeding was slight immediately ing in injured skin and that this response is after wounding, and leukocytic infiltration occlosely related to that of surrounding keratino- curred after 3—4 hours. Within 20 hours there eytes. Previously, melanoeytes in mitosis have was a generalized edema and vascular dilation
been observed by Bizzozero (1) in man, in the dermis and a layer of polymorphoBillingham (2) in guinea pigs, and by others nuclear cells separated the uninjured dermis in a variety of mammals. We have earlier from the wound. Epidermal proliferation and
migration began on the 2nd day and con-
shown (3) that epidermal melanocytes take up
tritiated thymidine after the skin is injured, tinued through the 6th day, when "tongues" hut at that time did not see them actually in of epidermis from the opposite sides of the wound came together and fused to close the mitosis. gap. The epidermal sheets then grew down MATERIALS AND METHODS
into the upper reaches of the dermis. After 10 Four young healthy male rhesus monkeys to 20 days there was an increased prolifera(Macaca mulatta) weighing between 3 and 4 kg tion of fibroblasts and collagen fibers became
were used. Under aseptic conditions, 3 cuts 10 mm
stratified in horizontal layers.
long and 4 mm deep were made with a blade on the scalp of each animal. This region was chosen because, unlike the skin elsewhere, it contains an appreciable population of melanotic epidermal melanocytes (4). The wounds were not sutured nor was a dressing applied. Biopsy specimens of
We found melanoeytes in the advancing epithelium from the 2nd to the 5th day after wounding but they were behind its forward edge. Most of them contained a small amount the wounded skin were taken daily for 12 days and of melanin in the perikaryon and their dendrites were short or absent. Figures 1, 2, 3, 4, 5
fixed for 24 hours in Bouin's fluid. Phencydidine
and 6 show melanocytes undergoing typical mitotic division 6 to 10 days after wounding.
hydrochloride (Sernylan®), 0.5 mg/kg body weight,
injected parenterally, was used to establish basal narcosis at the time of the skin biopsy. The specimens were oriented so that the wound edge was cut transversely. Sections 6 thick were stained in Harris hematoxylin and eosin. All biopsy specimens were obtained at the same hour of the day (11:00 A.M.). The monkeys were kept in individual restraining chairs in a room where a constant temperature of 21° 2° C was maintained.
Since only melanocytes contain some pigment granules in the cytoplasm it was evident
that during the early phases of the healing of the wounds, some melanocytes were present
in advancing epithelial sheets but none were
present at any time in the advancing edge
They were fed a standard commercial monkey of the epithelial "tongues". Proliferation of
melanocytes always coincided with the epithelial closure of the incisional gap. These OBSERVATIONS cells, then, became active when the surroundWe will mention here only those details of ing epidermal cells displayed hyperplasia, an the process in the healing of these small increase in DNA synthesizing cells (5), and * From the Department of Cutaneous Biology, intensified mitotie activity (6). In the norchow with water ad libitum.
mal epidermis of these animals we have rarely
Oregon Regional Primate Research Center, Beaverton, Oregon.
Publication No. 289 from the Oregon Re- found dividing melanocytes. gional Primate Research Center; supported in part by Grant FR 00163 of the National Institutes COMMENTS of Health and by funds from Grant AM 08445, Biology of the Skin of Man and Other Primates; Since the reader may not be familiar with also supported by the Revlon Research Center, the melanocytes resident in the epidermis of Inc., New York. rhesus monkeys, we describe them briefly for Accepted for publication September 20, 1967. 273
274
a
•
£ve
•
S.
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
Fics. 1 and 2.—Late prophase. The chromosomes are coiliag up; the melanin granules are dispersed in the cytoplasm. Ftc. 3.—Prometaphase. The nuclear envelope has disappeared and the chromosomes are coiled into compact gyres. FIG. 4.—Metaphase. The chromosomes are arranged equatorially. Note a short spike laden with melanin, probably a retracted dendrite.
Ftc. 5—Em1y anaphase. The chromosomes begin to pull apart. Note the peripheral
localization of melanin granules. . FIG. 6.—Late anaphase. The chromosomes arc near the poles and the cell is beginning to pinch in two.
the purpose of orientation. Except for that of the nose, ears, and friction surfaces, the epidermis of the rhesus monkey is mostly free of melanotic melanocytes (8). In the hairy skin
a few melanin containing dopa-positive dendritic melanocytes are normally found only on the scalp (4). That the epidermis does contain a full complement of melanocytes, therefore,
SKIN WOUNDS IN PRIMATES
275
SUMMARY can be demonstrated by irradiating the skin with ultraviolet light (7). After such treatSmall wounds were made in the scalp of ment melanin containing, dopa-positive den- rhesus monkeys and biopsy specimens were
dritic cells appear in the basal epidermal excised daily. From the second to the fifth day layer but the melanin granules that they produce remain within their dendritie processes,
after wounding, epidermal melanocytes, mostly
Thus, these cells are different from the melano-
days after wounding, melanocytes were found
round and containing a few pigment granthere being no evidence that the keratino- ules, were found in the advancing epithelium cytes become the receptor cells of pigment. but not at the wound margin. From 6 to 10 cytes of most other species, and the separa- in all stages of mitosis. Damage to the skin,
tion of keratinoeytes from melanocytes here is then, provokes first a migration and then facilitated by the presence of melanin granules proliferation of both systems, keratinocytes in the former. and the accompanying melanocytes. Thus, the An account of the healing of cutaneous behavior of the melanocytes may depend upon
wounds in the rhesus monkey has already been given by Giacometti (6). In this study we add only information on the biological properties of the melanocytes which, to our knowledge, have been studied only in our laboratory (4, 7, 8). We emphasize that in the hairy skin of the rhesus monkey, these
the physiological condition and integrity of the surrounding epidermis.
REFERENCES 1. Bizzozero, E.: Sulle cellule cromatofore e di Langerhans nella pelle. Archivie per le science mediche, 30: 611, 1910.
2. Bilhngham, R. E.: Dendritic cells. J. Anat., 8: 93, 1948. cells are melanotic only on the scalp (4). They 3. Ciacometti, L. and Allegra, F.: The effect of are further unique in that when they become wounding upon the uptake of 811-Thymidine by guinea pig epidermal melanocytes. Admelanotic after stimulation with ultraviolet vonces in Biology of Skin. Vol. 8. The Pig-
light the melanin they form remains in their mentary System. Eds., Montagna, W. and flu, F., Pergamon Press, Oxford, England, 1967. own cytoplasm (7). The melanocytes, there4. Machida, H. and Perkins, E:: The distribution fore, are quickly separated from keratinocytes, of melanotic melanocytes in the skin of subhuman primates. Advonces in Biology of which are free of pigment. Since these melanSkin. Vol. 8. The Pigmcntary System. Eds., ocytes do not begin to divide until the 6th Montagna, W. and flu, F., Pergamon Press, day after wounding, when the incisional gap Oxford, England, 1967. has been bridged by the epithelial tongues, we
believe that there is a functional partnership between the melanocytes and the mal-
5. Celfand, S.: Initiation of mitosis in relation to the cell division cycle. Exp. Cell Res., 26: 395, 1962.
6. Giacometti, L.: The healing of skin wounds in primates. I. The kinetics of cell proliferation.
pighian system. The physiologic conditions and 3. Invest. Derm., 48: 133, 1967. integrity of the epidermis appear to determine 7. Yun, J. S. and Montagna, W.: The melanocytes in the epidermis of the rhesus monkey the behavior of the melanocytes in it. The major (Mecoce mulotle). Anat. Rec., .154: 161, 1966. purpose of this presentation has been to give a S. Montagna, W., Yun, J. S., and Machida, H.: The skin of primates. XVIII. The skin of the graphic documentation of the mitotic activity of rhesus monkey (Mococa mulotto). Am. 3. epidermal melanocytes in rhesus monkeys. Phys. Anthrop., 22: 307, 1964.
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
94
linolenic acid extract. Arch. This pdf is a scanned copy UV of irradiated a printed document.
24. Wynn, C. H. and Iqbal, M.: Isolation of rat
skin lysosomes and a comparison with liver Path., 80: 91, 1965. and spleen lysosomes. Biochem. J., 98: lOP, 37. Nicolaides, N.: Lipids, membranes, and the 1966.
human epidermis, p. 511, The Epidermis
Eds., Montagna, W. and Lobitz, W. C. Acascopic localization of acid phosphatase in demic Press, New York. human epidermis. J. Invest. Derm., 46: 431, 38. Wills, E. D. and Wilkinson, A. E.: Release of 1966. enzymes from lysosomes by irradiation and 26. Rowden, C.: Ultrastructural studies of kerathe relation of lipid peroxide formation to tinized epithelia of the mouse. I. Combined enzyme release. Biochem. J., 99: 657, 1966. electron microscope and cytochemical study 39. Lane, N. I. and Novikoff, A. B.: Effects of of lysosomes in mouse epidermis and esoarginine deprivation, ultraviolet radiation and X-radiation on cultured KB cells. J. phageal epithelium. J. Invest. Derm., 49: 181, 25. Olson, R. L. and Nordquist, R. E.: Ultramicro-
No warranty is given about the accuracy of the copy.
Users should refer to the original published dermal cells. Nature, 216: 1031, 1967. version of1965. the material. vest. Derm., 45: 448, 28. Hall, J. H., Smith, J. G., Jr. and Burnett, S. 41. Daniels, F., Jr. and Johnson, B. E.: In prepa1967.
Cell Biol., 27: 603, 1965.
27. Prose, P. H., Sedlis, E. and Bigelow, M.: The 40. Fukuyama, K., Epstein, W. L. and Epstein, demonstration of lysosomes in the diseased J. H.: Effect of ultraviolet light on RNA skin of infants with infantile eczema. J. Inand protein synthesis in differentiated epi-
C.: The lysosome in contact dermatitis: A ration. histochemical study. J. Invest. Derm., 49: 42. Ito, M.: Histochemical investigations of Unna's oxygen and reduction areas by means of 590, 1967. 29. Pearse, A. C. E.: p. 882, Histochemistry Theoultraviolet irradiation, Studies on Melanin, retical and Applied, 2nd ed., Churchill, London, 1960.
30. Pearse, A. C. E.: p. 910, Histacheini.stry Thearetscal and Applied, 2nd ed., Churchill, London, 1960.
31. Daniels, F., Jr., Brophy, D. and Lobitz, W. C.: Histochemical responses of human skin fol-
lowing ultraviolet irradiation. J. Invest. Derm.,37: 351, 1961.
32. Bitensky, L.: The demonstration of lysosomes by the controlled temperature freezing section method. Quart. J. Micr. Sci., 103: 205, 1952.
33. Diengdoh, J. V.: The demonstration of lysosomes in mouse skin. Quart. J. Micr. Sci., 105: 73, 1964.
34. Jarret, A., Spearman, R. I. C. and Hardy, J. A.:
Tohoku, J. Exp. Med., 65: Supplement V, 10, 1957.
43. Bitcnsky, L.: Lysosomes in normal and pathological cells, pp. 362—375, Lysasames Eds., de Reuck, A. V. S. and Cameron, M. Churchill, London, 1953.
44. Janoff, A. and Zweifach, B. W.: Production of inflammatory changes in the microcirculation by cationic proteins extracted from lysosomes. J. Exp. Med., 120: 747, 1964.
45. Herion, J. C., Spitznagel, J. K., Walker, R. I. and Zeya, H. I.: Pyrogenicity of granulocyte lysosomes. Amer. J. Physiol., 211: 693, 1966.
46. Baden, H. P. and Pearlman, C.: The effect of ultraviolet light on protein and nucleic acid synthesis in the epidermis. J. Invest. Derm.,
Histochemistry of keratinization. Brit. J. 43: 71, 1964. Derm., 71: 277, 1959. 35. De Duve, C. and Wattiaux, R.: Functions of 47. Bullough, W. S. and Laurence, E. B.: Mitotic control by internal secretion: the role of lysosomes. Ann. Rev. Physiol., 28: 435, 1966. the chalone-adrenalin complex. Exp. Cell. 36. Waravdekar, V. S., Saclaw, L. D., Jones, W. A. and Kuhns, J. C.: Skin changes induced by
Res., 33: 176, 1964.
THE JOURNAL OF INYESTIOATIYE DERMATOLOGY
Copyright
Printed in U.S.A.
1968 by The Williams & Wilkins Co.
THE HEALING OF SKIN WOUNDS IN PRIMATES II. THE PEOLIFEnATION OF EPIDEILMAL CELL MELANOCYTES*
LUIGI GIACOMETTI, PH.D. AND WILLIAM MONTAGNA, Pn.D.
In this short report we will show that epi- wounds that are relevant to proliferation of dermal melanoeytes are capable of proliferat- melanocytes. Bleeding was slight immediately ing in injured skin and that this response is after wounding, and leukocytic infiltration occlosely related to that of surrounding keratino- curred after 3—4 hours. Within 20 hours there eytes. Previously, melanoeytes in mitosis have was a generalized edema and vascular dilation
been observed by Bizzozero (1) in man, in the dermis and a layer of polymorphoBillingham (2) in guinea pigs, and by others nuclear cells separated the uninjured dermis in a variety of mammals. We have earlier from the wound. Epidermal proliferation and
migration began on the 2nd day and con-
shown (3) that epidermal melanocytes take up
tritiated thymidine after the skin is injured, tinued through the 6th day, when "tongues" hut at that time did not see them actually in of epidermis from the opposite sides of the wound came together and fused to close the mitosis. gap. The epidermal sheets then grew down MATERIALS AND METHODS
into the upper reaches of the dermis. After 10 Four young healthy male rhesus monkeys to 20 days there was an increased prolifera(Macaca mulatta) weighing between 3 and 4 kg tion of fibroblasts and collagen fibers became
were used. Under aseptic conditions, 3 cuts 10 mm
stratified in horizontal layers.
long and 4 mm deep were made with a blade on the scalp of each animal. This region was chosen because, unlike the skin elsewhere, it contains an appreciable population of melanotic epidermal melanocytes (4). The wounds were not sutured nor was a dressing applied. Biopsy specimens of
We found melanoeytes in the advancing epithelium from the 2nd to the 5th day after wounding but they were behind its forward edge. Most of them contained a small amount the wounded skin were taken daily for 12 days and of melanin in the perikaryon and their dendrites were short or absent. Figures 1, 2, 3, 4, 5
fixed for 24 hours in Bouin's fluid. Phencydidine
and 6 show melanocytes undergoing typical mitotic division 6 to 10 days after wounding.
hydrochloride (Sernylan®), 0.5 mg/kg body weight,
injected parenterally, was used to establish basal narcosis at the time of the skin biopsy. The specimens were oriented so that the wound edge was cut transversely. Sections 6 thick were stained in Harris hematoxylin and eosin. All biopsy specimens were obtained at the same hour of the day (11:00 A.M.). The monkeys were kept in individual restraining chairs in a room where a constant temperature of 21° 2° C was maintained.
Since only melanocytes contain some pigment granules in the cytoplasm it was evident
that during the early phases of the healing of the wounds, some melanocytes were present
in advancing epithelial sheets but none were
present at any time in the advancing edge
They were fed a standard commercial monkey of the epithelial "tongues". Proliferation of
melanocytes always coincided with the epithelial closure of the incisional gap. These OBSERVATIONS cells, then, became active when the surroundWe will mention here only those details of ing epidermal cells displayed hyperplasia, an the process in the healing of these small increase in DNA synthesizing cells (5), and * From the Department of Cutaneous Biology, intensified mitotie activity (6). In the norchow with water ad libitum.
mal epidermis of these animals we have rarely
Oregon Regional Primate Research Center, Beaverton, Oregon.
Publication No. 289 from the Oregon Re- found dividing melanocytes. gional Primate Research Center; supported in part by Grant FR 00163 of the National Institutes COMMENTS of Health and by funds from Grant AM 08445, Biology of the Skin of Man and Other Primates; Since the reader may not be familiar with also supported by the Revlon Research Center, the melanocytes resident in the epidermis of Inc., New York. rhesus monkeys, we describe them briefly for Accepted for publication September 20, 1967. 273
274
a
•
£ve
•
S.
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
Fics. 1 and 2.—Late prophase. The chromosomes are coiliag up; the melanin granules are dispersed in the cytoplasm. Ftc. 3.—Prometaphase. The nuclear envelope has disappeared and the chromosomes are coiled into compact gyres. FIG. 4.—Metaphase. The chromosomes are arranged equatorially. Note a short spike laden with melanin, probably a retracted dendrite.
Ftc. 5—Em1y anaphase. The chromosomes begin to pull apart. Note the peripheral
localization of melanin granules. . FIG. 6.—Late anaphase. The chromosomes arc near the poles and the cell is beginning to pinch in two.
the purpose of orientation. Except for that of the nose, ears, and friction surfaces, the epidermis of the rhesus monkey is mostly free of melanotic melanocytes (8). In the hairy skin
a few melanin containing dopa-positive dendritic melanocytes are normally found only on the scalp (4). That the epidermis does contain a full complement of melanocytes, therefore,
SKIN WOUNDS IN PRIMATES
275
SUMMARY can be demonstrated by irradiating the skin with ultraviolet light (7). After such treatSmall wounds were made in the scalp of ment melanin containing, dopa-positive den- rhesus monkeys and biopsy specimens were
dritic cells appear in the basal epidermal excised daily. From the second to the fifth day layer but the melanin granules that they produce remain within their dendritie processes,
after wounding, epidermal melanocytes, mostly
Thus, these cells are different from the melano-
days after wounding, melanocytes were found
round and containing a few pigment granthere being no evidence that the keratino- ules, were found in the advancing epithelium cytes become the receptor cells of pigment. but not at the wound margin. From 6 to 10 cytes of most other species, and the separa- in all stages of mitosis. Damage to the skin,
tion of keratinoeytes from melanocytes here is then, provokes first a migration and then facilitated by the presence of melanin granules proliferation of both systems, keratinocytes in the former. and the accompanying melanocytes. Thus, the An account of the healing of cutaneous behavior of the melanocytes may depend upon
wounds in the rhesus monkey has already been given by Giacometti (6). In this study we add only information on the biological properties of the melanocytes which, to our knowledge, have been studied only in our laboratory (4, 7, 8). We emphasize that in the hairy skin of the rhesus monkey, these
the physiological condition and integrity of the surrounding epidermis.
REFERENCES 1. Bizzozero, E.: Sulle cellule cromatofore e di Langerhans nella pelle. Archivie per le science mediche, 30: 611, 1910.
2. Bilhngham, R. E.: Dendritic cells. J. Anat., 8: 93, 1948. cells are melanotic only on the scalp (4). They 3. Ciacometti, L. and Allegra, F.: The effect of are further unique in that when they become wounding upon the uptake of 811-Thymidine by guinea pig epidermal melanocytes. Admelanotic after stimulation with ultraviolet vonces in Biology of Skin. Vol. 8. The Pig-
light the melanin they form remains in their mentary System. Eds., Montagna, W. and flu, F., Pergamon Press, Oxford, England, 1967. own cytoplasm (7). The melanocytes, there4. Machida, H. and Perkins, E:: The distribution fore, are quickly separated from keratinocytes, of melanotic melanocytes in the skin of subhuman primates. Advonces in Biology of which are free of pigment. Since these melanSkin. Vol. 8. The Pigmcntary System. Eds., ocytes do not begin to divide until the 6th Montagna, W. and flu, F., Pergamon Press, day after wounding, when the incisional gap Oxford, England, 1967. has been bridged by the epithelial tongues, we
believe that there is a functional partnership between the melanocytes and the mal-
5. Celfand, S.: Initiation of mitosis in relation to the cell division cycle. Exp. Cell Res., 26: 395, 1962.
6. Giacometti, L.: The healing of skin wounds in primates. I. The kinetics of cell proliferation.
pighian system. The physiologic conditions and 3. Invest. Derm., 48: 133, 1967. integrity of the epidermis appear to determine 7. Yun, J. S. and Montagna, W.: The melanocytes in the epidermis of the rhesus monkey the behavior of the melanocytes in it. The major (Mecoce mulotle). Anat. Rec., .154: 161, 1966. purpose of this presentation has been to give a S. Montagna, W., Yun, J. S., and Machida, H.: The skin of primates. XVIII. The skin of the graphic documentation of the mitotic activity of rhesus monkey (Mococa mulotto). Am. 3. epidermal melanocytes in rhesus monkeys. Phys. Anthrop., 22: 307, 1964.
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
94
linolenic acid extract. Arch. This pdf is a scanned copy UV of irradiated a printed document.
24. Wynn, C. H. and Iqbal, M.: Isolation of rat
skin lysosomes and a comparison with liver Path., 80: 91, 1965. and spleen lysosomes. Biochem. J., 98: lOP, 37. Nicolaides, N.: Lipids, membranes, and the 1966.
human epidermis, p. 511, The Epidermis
Eds., Montagna, W. and Lobitz, W. C. Acascopic localization of acid phosphatase in demic Press, New York. human epidermis. J. Invest. Derm., 46: 431, 38. Wills, E. D. and Wilkinson, A. E.: Release of 1966. enzymes from lysosomes by irradiation and 26. Rowden, C.: Ultrastructural studies of kerathe relation of lipid peroxide formation to tinized epithelia of the mouse. I. Combined enzyme release. Biochem. J., 99: 657, 1966. electron microscope and cytochemical study 39. Lane, N. I. and Novikoff, A. B.: Effects of of lysosomes in mouse epidermis and esoarginine deprivation, ultraviolet radiation and X-radiation on cultured KB cells. J. phageal epithelium. J. Invest. Derm., 49: 181, 25. Olson, R. L. and Nordquist, R. E.: Ultramicro-
No warranty is given about the accuracy of the copy.
Users should refer to the original published dermal cells. Nature, 216: 1031, 1967. version of1965. the material. vest. Derm., 45: 448, 28. Hall, J. H., Smith, J. G., Jr. and Burnett, S. 41. Daniels, F., Jr. and Johnson, B. E.: In prepa1967.
Cell Biol., 27: 603, 1965.
27. Prose, P. H., Sedlis, E. and Bigelow, M.: The 40. Fukuyama, K., Epstein, W. L. and Epstein, demonstration of lysosomes in the diseased J. H.: Effect of ultraviolet light on RNA skin of infants with infantile eczema. J. Inand protein synthesis in differentiated epi-
C.: The lysosome in contact dermatitis: A ration. histochemical study. J. Invest. Derm., 49: 42. Ito, M.: Histochemical investigations of Unna's oxygen and reduction areas by means of 590, 1967. 29. Pearse, A. C. E.: p. 882, Histochemistry Theoultraviolet irradiation, Studies on Melanin, retical and Applied, 2nd ed., Churchill, London, 1960.
30. Pearse, A. C. E.: p. 910, Histacheini.stry Thearetscal and Applied, 2nd ed., Churchill, London, 1960.
31. Daniels, F., Jr., Brophy, D. and Lobitz, W. C.: Histochemical responses of human skin fol-
lowing ultraviolet irradiation. J. Invest. Derm.,37: 351, 1961.
32. Bitensky, L.: The demonstration of lysosomes by the controlled temperature freezing section method. Quart. J. Micr. Sci., 103: 205, 1952.
33. Diengdoh, J. V.: The demonstration of lysosomes in mouse skin. Quart. J. Micr. Sci., 105: 73, 1964.
34. Jarret, A., Spearman, R. I. C. and Hardy, J. A.:
Tohoku, J. Exp. Med., 65: Supplement V, 10, 1957.
43. Bitcnsky, L.: Lysosomes in normal and pathological cells, pp. 362—375, Lysasames Eds., de Reuck, A. V. S. and Cameron, M. Churchill, London, 1953.
44. Janoff, A. and Zweifach, B. W.: Production of inflammatory changes in the microcirculation by cationic proteins extracted from lysosomes. J. Exp. Med., 120: 747, 1964.
45. Herion, J. C., Spitznagel, J. K., Walker, R. I. and Zeya, H. I.: Pyrogenicity of granulocyte lysosomes. Amer. J. Physiol., 211: 693, 1966.
46. Baden, H. P. and Pearlman, C.: The effect of ultraviolet light on protein and nucleic acid synthesis in the epidermis. J. Invest. Derm.,
Histochemistry of keratinization. Brit. J. 43: 71, 1964. Derm., 71: 277, 1959. 35. De Duve, C. and Wattiaux, R.: Functions of 47. Bullough, W. S. and Laurence, E. B.: Mitotic control by internal secretion: the role of lysosomes. Ann. Rev. Physiol., 28: 435, 1966. the chalone-adrenalin complex. Exp. Cell. 36. Waravdekar, V. S., Saclaw, L. D., Jones, W. A. and Kuhns, J. C.: Skin changes induced by
Res., 33: 176, 1964.