105
J. Anat. (1975), 120, 1, pp. 105-112 With 6 figures Printed in Great Britain
Gland ultrastructure in human gall bladder MATTI LAITIO AND TIMO NEVALAINEN
Department ofPathological Anatomy and Laboratory of Electron Microscopy, University of Turku, Turku, Finland
(Accepted 1 January 1975) INTRODUCTION
The presence of glands in the neck region of the gall bladder is firmly established, whereas their presence in other parts of the organ has been under dispute for a long time. Schridde (1909) described glands in the fundus of inflamed gall bladders. Since then most authors favour the idea that the glands found outside the neck region are metaplastic (King & McCallum, 1931; Christie, 1954; Jarvi & Meurman, 1964; Hakkinen & Laitio, 1970). Such glands are often referred to as antral type (pseudoantral) glands, since they are believed to consist of cells very similar to those of the glands in the pyloric antrum of the stomach. The glands outside the neck region differ histologically and histochemically from the glands of the neck region (Laitio, unpublished). In man these glands have not been subjected to electron microscopic examination. In the present study, clear-cut ultrastructure differences were found between the cells of the glands of the neck region and those found in other parts of the gall bladder. MATERIALS AND METHODS
Pieces of mucosa from the neck, body and fundus of gall bladders removed for
gall stones were studied. Glands outside the neck region were studied in four gall bladders. The specimens were fixed in 3 0 glutaraldehyde in a phosphate buffer at pH 7*3 (Sabatini, Bensch & Barrnett, 1963) for 3 hours and post-fixed in 1 % osmium tetroxide (Millonig, 1961) for 1 hour. The tissues were dehydrated in ethanol and embedded in Epon 812 (Luft, 1961). Semithin (1 ,am) Epon sections were stained with toluidine blue (Trump, Smuckler & Benditt, 1961) and the periodic acid-Schiff technique (Nevalainen, Laitio & Lindgren, 1972). Thin sections (silver to gold) were stained with uranyl acetate (Watson, 1958) and lead citrate (Venable & Coggeshall, 1965) and studied in a Siemens Elmiskop IA electron microscope. RESU LTS
Light microscopy. Antral type glands of the gall bladder mucosa (Fig. 1) consisted of coiled tubules with frequent distal branchings. The lumen was relatively narrow. Apart from enterochromaffin cells, which were frequent, the glands were composed of a single type of mucus-secreting cell with a basal flattened nucleus and a cytoplasm filled with mucus droplets.
106
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2 Fig. 1. Antral type glands in the gall bladder. The gland lumen is rather narrow. The gland cells contain plenty of mucus, which is dark-stained in this preparation. On the right there are pale columnar cells of the gall bladder surface epithelium containing only a few mucin droplets in the apical cytoplasm. Light micrograph. PAS. x 450. Fig. 2. Glands of the neck region in the gall bladder. The gland lumen is wide. The gland cells are cuboidal and contain very few mucin granules. The nuclei are large, and round or oval in shape, and are located in the central parts of the cells. Light micrograph. PAS. x 450.
Gland ultrastructure in human gall Oladder
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108
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Fig. 5. Antral type gland cell containing plenty of mucin granules (MG). N, flattened nucleus; L, gland lumen; M, mitochondria. Between the mucus-containing cell and the basement membrane (B) there are 'endocrine type' cells (E) with typical small, round, dense secretory granules. x 800.
The glands of the neck region were different. The cells varied from cuboidal to columnar and the lumen of the gland was usually wider than that in the antral type glands. Secretory material was scanty: when present it was in the apical part of the cell but often it was difficult to find any secretory granules at all (Fig. 2). The nuclei were spherical or oval in shape and located centrally. Electron microscopy. The antral type gland cells were tall and columnar in shape. The secretory granules formed the most prominent features of these cells. The granules were large, pale, and usually concentrated in the apical region but often
110
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J. Anat. (1975), 120, 1, pp. 105-112 With 6 figures Printed in Great Britain
Gland ultrastructure in human gall bladder MATTI LAITIO AND TIMO NEVALAINEN
Department ofPathological Anatomy and Laboratory of Electron Microscopy, University of Turku, Turku, Finland
(Accepted 1 January 1975) INTRODUCTION
The presence of glands in the neck region of the gall bladder is firmly established, whereas their presence in other parts of the organ has been under dispute for a long time. Schridde (1909) described glands in the fundus of inflamed gall bladders. Since then most authors favour the idea that the glands found outside the neck region are metaplastic (King & McCallum, 1931; Christie, 1954; Jarvi & Meurman, 1964; Hakkinen & Laitio, 1970). Such glands are often referred to as antral type (pseudoantral) glands, since they are believed to consist of cells very similar to those of the glands in the pyloric antrum of the stomach. The glands outside the neck region differ histologically and histochemically from the glands of the neck region (Laitio, unpublished). In man these glands have not been subjected to electron microscopic examination. In the present study, clear-cut ultrastructure differences were found between the cells of the glands of the neck region and those found in other parts of the gall bladder. MATERIALS AND METHODS
Pieces of mucosa from the neck, body and fundus of gall bladders removed for
gall stones were studied. Glands outside the neck region were studied in four gall bladders. The specimens were fixed in 3 0 glutaraldehyde in a phosphate buffer at pH 7*3 (Sabatini, Bensch & Barrnett, 1963) for 3 hours and post-fixed in 1 % osmium tetroxide (Millonig, 1961) for 1 hour. The tissues were dehydrated in ethanol and embedded in Epon 812 (Luft, 1961). Semithin (1 ,am) Epon sections were stained with toluidine blue (Trump, Smuckler & Benditt, 1961) and the periodic acid-Schiff technique (Nevalainen, Laitio & Lindgren, 1972). Thin sections (silver to gold) were stained with uranyl acetate (Watson, 1958) and lead citrate (Venable & Coggeshall, 1965) and studied in a Siemens Elmiskop IA electron microscope. RESU LTS
Light microscopy. Antral type glands of the gall bladder mucosa (Fig. 1) consisted of coiled tubules with frequent distal branchings. The lumen was relatively narrow. Apart from enterochromaffin cells, which were frequent, the glands were composed of a single type of mucus-secreting cell with a basal flattened nucleus and a cytoplasm filled with mucus droplets.
106
MATTI LAITIO AND TIMO NEVALAINEN
W4.
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2 Fig. 1. Antral type glands in the gall bladder. The gland lumen is rather narrow. The gland cells contain plenty of mucus, which is dark-stained in this preparation. On the right there are pale columnar cells of the gall bladder surface epithelium containing only a few mucin droplets in the apical cytoplasm. Light micrograph. PAS. x 450. Fig. 2. Glands of the neck region in the gall bladder. The gland lumen is wide. The gland cells are cuboidal and contain very few mucin granules. The nuclei are large, and round or oval in shape, and are located in the central parts of the cells. Light micrograph. PAS. x 450.
Gland ultrastructure in human gall Oladder
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Fig. 3. Electron micrograph of antral type gland cells in the gall bladder. The apical cytoplasm is filled with pale mucus granules (MG) and bulges into the gland lumen (L). There are only a few irregular microvilli on the apical cell surface. The nuclei (N) are located in the basal cell parts and are flattened in outline. The Golgi apparatus (G) is prominent. The mitochondria (M) are scattered throughout the cytoplasm. B, basement membrane. x 8000.
108
MATTI LAITIO AND TIMO NEVALAINEN
MG.' 14 ob,
.........
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Fig. 4. Antral type gland cell in mitosis. The cell is more rounded, but retains its characteristic organelles, including mucin granules (MG). CH, chromatin masses of the mitotic cell; M, mitochondria; L, gland lumen with microvilli on the apical cell surface. x 10000.
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Fig. 5. Antral type gland cell containing plenty of mucin granules (MG). N, flattened nucleus; L, gland lumen; M, mitochondria. Between the mucus-containing cell and the basement membrane (B) there are 'endocrine type' cells (E) with typical small, round, dense secretory granules. x 800.
The glands of the neck region were different. The cells varied from cuboidal to columnar and the lumen of the gland was usually wider than that in the antral type glands. Secretory material was scanty: when present it was in the apical part of the cell but often it was difficult to find any secretory granules at all (Fig. 2). The nuclei were spherical or oval in shape and located centrally. Electron microscopy. The antral type gland cells were tall and columnar in shape. The secretory granules formed the most prominent features of these cells. The granules were large, pale, and usually concentrated in the apical region but often
110
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