Download Lysosomal Heterogeneity in Exocrine Acinar Cells

0022-1 554183/01022202S03.00
The Journal of Histochemistry and Cytochemistry
Vol. 31, No. IA, pp. 222-223, 1983
Printed in U.S.A.
Copyright © 1983 by The Histochemical Society, Inc.
Lysosomal Heterogeneity in Exocrine Acinar Cells 1
CONSTANCE OLIVER
Laboratory of Biological Structure, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20205
(OA 82-282P2)
Acid phosphatase (AcPase) has long been recognized as the
marker enzyme for lysosomes (3). In exocrine secretory cells
(2,4), AcPase activity is localized in GERL, immature secretory
granules, and some, but not all, lysosomes (Figure 1). The
lysosomes that possess AcPase activity are generally located
adjacent to the Golgi apparatus, frequently, on the cis side,
and include autophagic vacuoles, residual bodies, and dense
bodies. AcPase activity is only rarely observed in lysosomes
in the basal portion of the acinar cells (5). The basal lysosomes
are characterized by the presence of trimetaphosphatase activity (TMPase) (Figure 2). Nonspecific esterase and aryl sulfatase B activities have also been demonstrated in these lysosomes (6). TMPase, esterase, and aryl sulfatase activities can
also be localized in lysosomes adjacent to the Golgi apparatus,
but not in Golgi saccules or GERL (Figures 3, 4, 4 inset).
Morphologically, the basal lysosomes are very pleomorphic in
nature. They are often intercalated between cisternae of the
rough endoplasmic reticulum (RER) and are closely associated
with both the RER and mitochondria (Figure 4).
It thus appears that there is a morphological and cytochemical heterogeneity among the lysosomes in exocrine acinar cells (Figure 5). The significance of this heterogeneity is
unclear. The basal lysosomes represent a distinct component
of the lysosomal system that is involved, at least partially, in
the processing of endocytosed substances (7). The lysosomes
adjacent to the Golgi apparatus are typical secondary lysosomes by morphological and cytochemical criteria. The lack
of AcPase activity in a significant number of lysosomes and
its presence in GERL and immature secretory granules raise
'Presented as part of the program at the 1982 Joint Meeting of
the American and Japanese Histochemical Societies, held in Vancouver, British Columbia, Canada, July 20-24, 1982.
222
questions as to the role of acid phosphatase in secretory cells.
Acid phosphatase may function in the posttranslational modification of secretory proteins and/or lysosomal enzymes (1),
rather than being a true lysosomal enzyme involved primarily
in intracellular degradation. The cytochemical heterogeneity
observed in lysosomes in exocrine secretory cells also underscores the necessity of utilizing multiple substrates when examining the lysosomal system.
Literature Cited
1. Bennett G, O'Shaughnessy D: The site of incorporation of sialic
acid residues into glycoproteins and the subsequent fates of these
molecules in various rat and mouse cell types as shown by radioautography after injection of 3 H)N-acetylmannosamine. I. Observations in hepatocytes. J Cell Biol 88:1, 1981
2. Hand AR, Oliver C: Cytochemical studies of GERL and its role
in secretory granule formation in exocrine cells. Histochem J 9:375,
[
1977
3. Novikoff AB: The endoplasmic reticulum: a cytochemist's view (a
review). Proc Natl Acad Sci USA 73:2781, 1976
4. Novikoff AB, Novikoff PM: Cytochemical contributions to differentiating GERL from the Golgi apparatus. HistochemJ 9:525,
1977
5. Oliver C: Cytochemical localization of acid phosphatase and trimetaphosphatase activities in exocrine acinar cells. J Histochem
Cytochem 28:78, 1980
6. Oliver C: Enzyme cytochemical studies of basal lysosomes in exocrine acinar cells. J Histochem Cytochem 29:898, 1981
7. Oliver C: Endocytic pathways at the lateral and basal cell surfaces
of exocrine acinar cells. J Cell Biol 95:154,1982
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Figure 1. Rat exorbital lacrimal gland. Acid phosphatase activity is
localized in GERL (arrowheads), immature secretory granules (arrow),
and lysosomes (Ly and inset). G, Golgi saccules. Original magnification
x 21,500. Inset: Original magnification x 40,000. Bar = 0.5 gm.
Figure 2. Rat pancreas. Trimetaphosphatase activity is localized in
basal lysosomes (arrow) as well as more apically located lysosomes.
Original magnification x 7,500. Bar = 1 gm.
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Figure 3. Rat parotid gland. Nonspecific esterase activity is present
in a lysosome (large arrow) on the cis side of the Golgi apparatus (G),
but is absent from GERL (arrowheads) and immature secretory granules (small arrow). Original magnification x 31,000. Bar = 0.5 gm.
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Figure 4. Rat pancreas. Trimetaphosphatase activity is present in basal D
lysosomes and typical secondary lysosomes (inset). The basal lysosomes are frequently intercalated between PER cicternae and show a
close relationship to mitochondria (M). PM, plasma membrane. Original magnification x 37,000. Inset:.Original magnification x 22,000.
Bar =0.5gin.
Figure 5. AcPase activity (black) is localized primarily in GERL, immature secretory granules and lysosomes adjacent to the Golgi ap- paratus, while trimetaphosphatase activity (stippled) is seen in lyso-
somes in the basal region. Some lysosomes adjacent to the Golgi apparatus contain both activities (hatched). ISG, immature secretory granule.
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