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Ultrastructural morphology of secretory granules in pleomorphic adenoma of human parotid and submandibular salivary glands
0003-9969/89 S3.00 + 0.00
Archs oral Bid. Vol. 34, NC,. 9, pp. 759-761, 1989 Printed in Great Britain. All rights reserved
Copyright 0 1989MaxwellPergamon Macmillan plc
SHORT COMMUNICATION ULTRASTRUCTURAL MORPHOLOGY OF SECRETORY GRANULES IN PLEOMORPHIC ADENOMA OF HUMAN PAROTID AND SUBMANDIBULAR SALIVARY GLANDS J. D. HARRISONand D. W. AUGER Department of Oral Pathology, The Rayne Institute, King’s College School of Medicine and Dentistry, 123 Coldharbour Lane, London SE5 9NU, England (Accepted
8 March
1989)
Summary-Secretory granules were found in some of the cells lining the lumina of typical epithelial structures in pleomorphic adenomas. They were small, of varied electron density, and were mostly unipartite, sometimes bipartite and occasionally tripartite. They most closely resembled secretory granules of intercalary ductal cells of normal salivary glands.
Several ultrastructural investigations have noted that there are secretory granules in some of the cells lining
lumina of the typical epithelial structures of salivary pleomorphic adenoma (Eneroth and Werslll, 1966; Welsh and Meyer, 1968; Innes and Cutler, 1978; Harrison and Auger, 1982; Dardick et al., 1983a; Erlandson, Cordon-Cardo and Higgins, 1984; Palmer, Lucas and Langdon, 1985; Caselitz, 1986), but there has been little attempt to describe their morphology. Similari ties between ceils of pleomorphic adenoma and those of salivary glands have been used to suggest the origin of the tumour (Dardick et al., 1983a, b; Erlandson et al., 1984; Lam, 1985; Palmer et al., 1985). However, secretory granules have not been considered in these comparisons, although they are an essential and complex component of salivary glands (Auger and Harrison, 1982; Harrison et al., 1987a, b). Therefore we have now sought to examine the ultrastructural morphology of secretory granules of salivary pleomorphic adenoma, and to compare them with the secretory granules of salivary glands. Seven pleomorphic adenomas, six of the parotid and one of the submandibular gland, were obtained immediately upon removal under general anaesthesia. Small pieces of less than 2 mm greatest dimension were immersed in a solution (Karnovsky, 1965), containing 5% glutaraldehyde, 4% formaldehyde prepared from paraformaldehyde, 0.05% CaCl, and 0.08 M cacodylate buffer, pH 7.2, at room temperature for 2 h, followed by rinsing in 7.5% sucrose in 0.05 M cacodylate buffer, pH 7.2, at 0-4”C, followed by osmication, dehydration and embedding in Araldite. Ultra-thin sections were stained with lead citrate and uranyl acet,ate and were examined electron microscopically. Secretory granules were concentrated luminally in some of the cells lining the lumina of typical epithelial structures (Figs l-3). They were small and usually ranged in diameter from about 0.2-0.8pm. They were most often unipartite, sometimes bipartite, and
occasionally tripartite, and were not seen comprising more than three parts. The contents of unipartite granules varied from amorphous material of high electron density to granular material of moderate electron density to fine reticular material of overall low electron density. The bipartite granules contained a spherule of high electron density and a larger surrounding part that varied in appearance from granular and moderately electron dense to reticular and of overall low electron density. The tripartite granules also contained a small, extremely electron dense spherule, either in the larger spherule or in the surrounding part. The secretory granules were usually rounded but sometimes elongated; some of those containing reticular material were irregular in shape and sometimes appeared to have fused with each other. Variation in the size and contents of the granules was greatest between different cells, but some variation was seen within individual cells. Material of similar appearance to that of the various parts of the secretory granules was seen in the lumina. There were inconspicuous granular endoplasmic reticulum and Golgi organelles in the cells that contained secretory granules. The morphological variation and complexity of these secretory granules was not as great as that found in parotid and submandibular salivary glands that were removed with the tumours and during other operations (Auger and Harrison, 1982; Harrison et al., 1987a, b). The typical secretory granules of pleomorphic adenomas are of similar size, shape, luminal distribution and appearance to those of intercalary ductal cells of the normal glands. Similarities between luminal tumour cells and intercalary ductal cells have also been found immunohistochemically (Korsrud and Brandtzaeg, 1984; Caselitz et al., 1985). Morphological similarities between the tumour cells and those of normal glands have been considered in attempts to identify the cell from which the pleomorphic adenoma originates; myoepithelial cells,
159
J. D. HARRISON and D. W. AUGER
760 ductal cells, and the complete
ductal and acinar unit
have been variously suggested as a possible origin (Dardick et al., 1983a, b; Erlandson et al., 1984; Lam, 1985; Palmer et al., 1985). However, the similarities between luminal tumour cells and intercalary ductal cells do not confirm that the intercalary duct is the site of the cell from which the tumour develops, but only that some of the progeny of this cell develop certain features found in intercalary ductal cells. Possibly the similarities relate to mechanisms underlying the formation of secretory material in salivary cells. There are similarities between the secretory granules of tumour cells and intercalary ductal cells, and those of human fetal parotid and submandibular salivary glands (Donath, Dietrich and Seifert, 1978; Gibson, 1983; Yaku, 1983), and possibly this appearance represents the synthetic potential of a simple salivary luminal cell with a low level of secretory activity. Nervous stimulation and hormones are apparently involved in salivary synthesis (Garrett, 1987; Johnson et al., 1987), and while both might be factors in the production of the more varied and complex morphology of secretory granules in mature salivary glands, hormones alone might be a factor in the production of the secretory granules of the luminal cells of pleomorphic adenoma. Acknowledgements-We gratefully acknowledge the financial support of the Medical Research Council and the technical assistance of Mr P. S. A. Rowley.
REFERENCES Auger D. W. and Harrison J. D. (1982) Ultrastructural
phosphatase cytochemistry of the intercalary ducts of the parotid and submandibular salivary glands of man. Archs oral Biol. 21, 79-8 1. Caselitz J. (1986) Das pleomorphe Adenom der Speicheldriisen. Histogenese, zellullre Differenzierung, Tumormarken. Veriiff. Path. 126. Caselitz J., Lunau U., Hamper K., Walther B. and Schmieaelow P. (1985) The uleomorohic adenoma of saliva&glands transplanted on athymic mice. A light microscopical
and immunohistochemical
investigation.
Virchows Arch. (A) 408, 191-209.
Dardick I., Nostrand A. W. P. van, Rippstein P. and Edwards V. (1983a) noma, I: Ultrastructural organization gions. Hum. Path. 14, 780-797. Dardick I., Nostrand A. W. P. van, Rippstein P. and Edwards V. (1983b)
noma, II: Ultrastructural organization of ‘stromal’ regions. Hum. Path. 14, 798-809. Donath K., Dietrich H. and Seifert G. (1978) Entwicklung und ultrastrukturelle Cytodifferenzierung der Parotis des Menschen. Virchows Arch. (A) 378, 297-314. Eneroth C.-M. and Wersiill J. (1966) Fine structure of the epithelial cells in mixed tumors of the parotid gland. Ann. Otol. Rhinol. Lar. 75, 95-102. Erlandson R. A., Cordon-Cardo C. and Higgins P. J. (1984) Histogenesis of benign pleomorphic adenoma (mixed tumor) of the major salivary glands. An ultrastructural and immunohistochemical study. Am. J. surg. Path. 8, 803-820.
Garrett J. R. (1987) The proper role of nerves in salivary secretion: a review. J. dent. Res. 66, 387-397. Gibson M. H. L. (1983) The prenatal human submandibular gland: a histological, histochemical and ultrastructural study. Anal. Anz. 153, 91-105. Harrison J. D. and Auger D. W. (1982) Ultrastructural cytochemistry of phosphatases in the ductal component of pleomorphic adenoma of human parotid and submandibular salivary glands. Hisrochem. J. 14, 703-7 11.
Harrison J. D., Auger, D. W., Badir M. S. and Paterson K. L. (1987a) Ultrastructural morphology of secretory granules of submandibular and parotid salivary glands of man. Archs oral Biol. 32, 229-234, Harrison J. D., Auger D. W., Paterson K. L. and Rowley P. S. A. (1987b) Mucin histochemistrv of submandibular and parotid sahvary glands of man:- light and electron microscopy. Histochem. J. 19, 555-564. Innes D. J. and Cutler L. S. (1978) Phosphatase enzymes. Cytochemical study of pleomorphic adenoma and normal human salivary glands. Archs Path. 102, 9&94. Johnson D. A.. Alvares 0. F.. Etzel K. R. and Kalu D. N. (1987) Regulation of salivary proteins. J. dent. Res. 66, 576582. Karnovsky M. J. (1965) A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy. J. Cell Biol. 27, 137A-138A. Korsrud F. R. and Brandtzaeg P. (1984) Immunofluorescence study of secretory epithelial markers in pleomorphic adenomas. Virchows Arch. (A) 403, 291-300.
Lam R. M. Y. (1985) An electron microscopic histochemical study of the histogenesis of major salivary gland pleomorphic adenoma. Ultrastruct. Path. 8, 207-223. Palmer R. M., Lucas R. B. and Langdon J. D. (1985) Ultrastructural analysis of salivary gland pleomorphic adenoma, with particular reference to myoepithelial cells. Histopathology 9, 1061-1076.
Jeans M. T. D., Pleomorphic adeof ‘epithelial’ reJeans M. T. D., Pleomorphic ade-
Welsh R. A. and Meyer A. T. (1968) Mixed tumors of human salivary gland. Histogenesis. Archs Pal. 85, 433447.
Yaku Y. (1983) Ultrastructural studies on the development of human fetal salivary glands. Archs hist. Jap. 46, 677-690.
Plate l Fig. 1. Unipartite secretory granules are concentrated luminally in epithelial cells surrounding a lumen in a parotid pleomorphic adenoma. These show great morphological variation between cells and a limited amount within cells. x 7750 Fig. 2. Bipartite and apparently unipartite secretory granules in a luminal cell of a parotid pleomorphic adenoma. Membranous debris is present and has apparently been taken up from the lumen that is seen at the bottom of the micrograph. x 24,270 Fig. 3. Bipartite and tripartite (arrows) secretory granules in a luminal cell of a parotid pleomorphic adenoma. x 24,390
Pleomorphic
Plate
adenoma
I
761
Archs oral Bid. Vol. 34, NC,. 9, pp. 759-761, 1989 Printed in Great Britain. All rights reserved
Copyright 0 1989MaxwellPergamon Macmillan plc
SHORT COMMUNICATION ULTRASTRUCTURAL MORPHOLOGY OF SECRETORY GRANULES IN PLEOMORPHIC ADENOMA OF HUMAN PAROTID AND SUBMANDIBULAR SALIVARY GLANDS J. D. HARRISONand D. W. AUGER Department of Oral Pathology, The Rayne Institute, King’s College School of Medicine and Dentistry, 123 Coldharbour Lane, London SE5 9NU, England (Accepted
8 March
1989)
Summary-Secretory granules were found in some of the cells lining the lumina of typical epithelial structures in pleomorphic adenomas. They were small, of varied electron density, and were mostly unipartite, sometimes bipartite and occasionally tripartite. They most closely resembled secretory granules of intercalary ductal cells of normal salivary glands.
Several ultrastructural investigations have noted that there are secretory granules in some of the cells lining
lumina of the typical epithelial structures of salivary pleomorphic adenoma (Eneroth and Werslll, 1966; Welsh and Meyer, 1968; Innes and Cutler, 1978; Harrison and Auger, 1982; Dardick et al., 1983a; Erlandson, Cordon-Cardo and Higgins, 1984; Palmer, Lucas and Langdon, 1985; Caselitz, 1986), but there has been little attempt to describe their morphology. Similari ties between ceils of pleomorphic adenoma and those of salivary glands have been used to suggest the origin of the tumour (Dardick et al., 1983a, b; Erlandson et al., 1984; Lam, 1985; Palmer et al., 1985). However, secretory granules have not been considered in these comparisons, although they are an essential and complex component of salivary glands (Auger and Harrison, 1982; Harrison et al., 1987a, b). Therefore we have now sought to examine the ultrastructural morphology of secretory granules of salivary pleomorphic adenoma, and to compare them with the secretory granules of salivary glands. Seven pleomorphic adenomas, six of the parotid and one of the submandibular gland, were obtained immediately upon removal under general anaesthesia. Small pieces of less than 2 mm greatest dimension were immersed in a solution (Karnovsky, 1965), containing 5% glutaraldehyde, 4% formaldehyde prepared from paraformaldehyde, 0.05% CaCl, and 0.08 M cacodylate buffer, pH 7.2, at room temperature for 2 h, followed by rinsing in 7.5% sucrose in 0.05 M cacodylate buffer, pH 7.2, at 0-4”C, followed by osmication, dehydration and embedding in Araldite. Ultra-thin sections were stained with lead citrate and uranyl acet,ate and were examined electron microscopically. Secretory granules were concentrated luminally in some of the cells lining the lumina of typical epithelial structures (Figs l-3). They were small and usually ranged in diameter from about 0.2-0.8pm. They were most often unipartite, sometimes bipartite, and
occasionally tripartite, and were not seen comprising more than three parts. The contents of unipartite granules varied from amorphous material of high electron density to granular material of moderate electron density to fine reticular material of overall low electron density. The bipartite granules contained a spherule of high electron density and a larger surrounding part that varied in appearance from granular and moderately electron dense to reticular and of overall low electron density. The tripartite granules also contained a small, extremely electron dense spherule, either in the larger spherule or in the surrounding part. The secretory granules were usually rounded but sometimes elongated; some of those containing reticular material were irregular in shape and sometimes appeared to have fused with each other. Variation in the size and contents of the granules was greatest between different cells, but some variation was seen within individual cells. Material of similar appearance to that of the various parts of the secretory granules was seen in the lumina. There were inconspicuous granular endoplasmic reticulum and Golgi organelles in the cells that contained secretory granules. The morphological variation and complexity of these secretory granules was not as great as that found in parotid and submandibular salivary glands that were removed with the tumours and during other operations (Auger and Harrison, 1982; Harrison et al., 1987a, b). The typical secretory granules of pleomorphic adenomas are of similar size, shape, luminal distribution and appearance to those of intercalary ductal cells of the normal glands. Similarities between luminal tumour cells and intercalary ductal cells have also been found immunohistochemically (Korsrud and Brandtzaeg, 1984; Caselitz et al., 1985). Morphological similarities between the tumour cells and those of normal glands have been considered in attempts to identify the cell from which the pleomorphic adenoma originates; myoepithelial cells,
159
J. D. HARRISON and D. W. AUGER
760 ductal cells, and the complete
ductal and acinar unit
have been variously suggested as a possible origin (Dardick et al., 1983a, b; Erlandson et al., 1984; Lam, 1985; Palmer et al., 1985). However, the similarities between luminal tumour cells and intercalary ductal cells do not confirm that the intercalary duct is the site of the cell from which the tumour develops, but only that some of the progeny of this cell develop certain features found in intercalary ductal cells. Possibly the similarities relate to mechanisms underlying the formation of secretory material in salivary cells. There are similarities between the secretory granules of tumour cells and intercalary ductal cells, and those of human fetal parotid and submandibular salivary glands (Donath, Dietrich and Seifert, 1978; Gibson, 1983; Yaku, 1983), and possibly this appearance represents the synthetic potential of a simple salivary luminal cell with a low level of secretory activity. Nervous stimulation and hormones are apparently involved in salivary synthesis (Garrett, 1987; Johnson et al., 1987), and while both might be factors in the production of the more varied and complex morphology of secretory granules in mature salivary glands, hormones alone might be a factor in the production of the secretory granules of the luminal cells of pleomorphic adenoma. Acknowledgements-We gratefully acknowledge the financial support of the Medical Research Council and the technical assistance of Mr P. S. A. Rowley.
REFERENCES Auger D. W. and Harrison J. D. (1982) Ultrastructural
phosphatase cytochemistry of the intercalary ducts of the parotid and submandibular salivary glands of man. Archs oral Biol. 21, 79-8 1. Caselitz J. (1986) Das pleomorphe Adenom der Speicheldriisen. Histogenese, zellullre Differenzierung, Tumormarken. Veriiff. Path. 126. Caselitz J., Lunau U., Hamper K., Walther B. and Schmieaelow P. (1985) The uleomorohic adenoma of saliva&glands transplanted on athymic mice. A light microscopical
and immunohistochemical
investigation.
Virchows Arch. (A) 408, 191-209.
Dardick I., Nostrand A. W. P. van, Rippstein P. and Edwards V. (1983a) noma, I: Ultrastructural organization gions. Hum. Path. 14, 780-797. Dardick I., Nostrand A. W. P. van, Rippstein P. and Edwards V. (1983b)
noma, II: Ultrastructural organization of ‘stromal’ regions. Hum. Path. 14, 798-809. Donath K., Dietrich H. and Seifert G. (1978) Entwicklung und ultrastrukturelle Cytodifferenzierung der Parotis des Menschen. Virchows Arch. (A) 378, 297-314. Eneroth C.-M. and Wersiill J. (1966) Fine structure of the epithelial cells in mixed tumors of the parotid gland. Ann. Otol. Rhinol. Lar. 75, 95-102. Erlandson R. A., Cordon-Cardo C. and Higgins P. J. (1984) Histogenesis of benign pleomorphic adenoma (mixed tumor) of the major salivary glands. An ultrastructural and immunohistochemical study. Am. J. surg. Path. 8, 803-820.
Garrett J. R. (1987) The proper role of nerves in salivary secretion: a review. J. dent. Res. 66, 387-397. Gibson M. H. L. (1983) The prenatal human submandibular gland: a histological, histochemical and ultrastructural study. Anal. Anz. 153, 91-105. Harrison J. D. and Auger D. W. (1982) Ultrastructural cytochemistry of phosphatases in the ductal component of pleomorphic adenoma of human parotid and submandibular salivary glands. Hisrochem. J. 14, 703-7 11.
Harrison J. D., Auger, D. W., Badir M. S. and Paterson K. L. (1987a) Ultrastructural morphology of secretory granules of submandibular and parotid salivary glands of man. Archs oral Biol. 32, 229-234, Harrison J. D., Auger D. W., Paterson K. L. and Rowley P. S. A. (1987b) Mucin histochemistrv of submandibular and parotid sahvary glands of man:- light and electron microscopy. Histochem. J. 19, 555-564. Innes D. J. and Cutler L. S. (1978) Phosphatase enzymes. Cytochemical study of pleomorphic adenoma and normal human salivary glands. Archs Path. 102, 9&94. Johnson D. A.. Alvares 0. F.. Etzel K. R. and Kalu D. N. (1987) Regulation of salivary proteins. J. dent. Res. 66, 576582. Karnovsky M. J. (1965) A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy. J. Cell Biol. 27, 137A-138A. Korsrud F. R. and Brandtzaeg P. (1984) Immunofluorescence study of secretory epithelial markers in pleomorphic adenomas. Virchows Arch. (A) 403, 291-300.
Lam R. M. Y. (1985) An electron microscopic histochemical study of the histogenesis of major salivary gland pleomorphic adenoma. Ultrastruct. Path. 8, 207-223. Palmer R. M., Lucas R. B. and Langdon J. D. (1985) Ultrastructural analysis of salivary gland pleomorphic adenoma, with particular reference to myoepithelial cells. Histopathology 9, 1061-1076.
Jeans M. T. D., Pleomorphic adeof ‘epithelial’ reJeans M. T. D., Pleomorphic ade-
Welsh R. A. and Meyer A. T. (1968) Mixed tumors of human salivary gland. Histogenesis. Archs Pal. 85, 433447.
Yaku Y. (1983) Ultrastructural studies on the development of human fetal salivary glands. Archs hist. Jap. 46, 677-690.
Plate l Fig. 1. Unipartite secretory granules are concentrated luminally in epithelial cells surrounding a lumen in a parotid pleomorphic adenoma. These show great morphological variation between cells and a limited amount within cells. x 7750 Fig. 2. Bipartite and apparently unipartite secretory granules in a luminal cell of a parotid pleomorphic adenoma. Membranous debris is present and has apparently been taken up from the lumen that is seen at the bottom of the micrograph. x 24,270 Fig. 3. Bipartite and tripartite (arrows) secretory granules in a luminal cell of a parotid pleomorphic adenoma. x 24,390
Pleomorphic
Plate
adenoma
I
761