Summary
The pancreatic acinar cells of rat embryos obtained at 15, 17, 19 and 21 days of gestation have been examined using fine-structural and morphometric techniques.
Morphometric analysis demonstrates significant variations in the average volume of the cell, nucleus and cytoplasm, and the volume, surface and numerical densities of various cytoplasmic organelles during fetal life. In particular, the volume and surface densities of rER exhibit maximal values at 19 days of gestation, suggesting that secretory proteins are produced most actively at this time. Further-more, membrane continuity between the nuclear envelope and rER is frequently discernible in acinar cells, indicating that at this stage the rER is mainly derived from the nuclear envelope. Zymogen granules first appear at 17 days of gesstation. By 21 days, they occupy the greater part of the cytoplasm of the acinar cells, no polarity being seen in their distribution pattern. No direct evidence for the secretion of zymogen granules has been observed during fetal life.
It therefore appears that membrane transport involved with intracellular movement of newly synthesized proteins from rER via the Golgi complex to zymogen granules occurs in one direction and lacks regulation.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bolender RP (1979) Surface area ratios. I. A stereological method for estimating average cell changes in membrane surface areas. Anat Rec 194:511–522
Carvalho de CAF, Laurindo FRM, Tage R, Sesso A (1978) Ultra-structural morphometric study on developing acinar cells of the rat pancreas and parotid gland. Acta Anat 101:234–244
Cope GH, Williams MA (1973) Quantitative analyses of the constituent membranes of parotid acinar cells and the changes evident after induced exocytosis. Z Zellforsch 145:311–330
Jamieson JD, Palade GE (1967a) Intracellular transport of secretory proteins in the pancreatic exocrine cell. I. Role of the peripheral elements of the Golgi complex. J Cell Biol 34:577–596
Jamieson JD, Palade GE (1967b) Intracellular transport of secretory proteins in the pancreatic exocrine cell. II. Transport to condensing vacuoles and zymogen granules. J Cell Biol 34:597–615
Jamieson JD, Palade GE (1971) Synthesis, intracellular transport, and discharge of secretory proteins in stimulated pancreatic exocrine cells. J Cell Biol 50:135–158
Larose M, Morisset J (1977) Acinar cell responsiveness to urecholine in the rat pancreas during fetal and early postnatal growth. Gastroenterology 73:530–533
Meldolesi J (1974) Dynamics of cytoplasmic membranes in guinea pig pancreatic acinar cells. I. Synthesis and turnover of membrane proteins. J Cell Biol 61:1–13
Meldolesi J, Jamieson JD, Palade GE (1971a) Composition of cellular membranes in the pancreas of the guinea pig. I. Isolation of membrane fractions. J Cell Biol 49:109–129
Meldolesi J, Jamieson JD, Palade GE (1971b) Composition of cellular membranes in the pancreas of the guinea pig. III. Enzyme activities. J Cell Biol 49:150–158
Munger BL (1958) A phase and electron microscopic study of cellular differentiation in pancreatic acinar cells of the mouse. Am J Anat 103:1–33
Parsa I, Marsh WH, Fitzgerald PJ (1969a) Pancreas acinar cell differentiation. I. Morphologic and enzymatic comparisons of embryonic rat pancreas and pancreatic anlage grown in organ culture. Am J Pathol 57:457–487
Parsa I, Marsh WH, Fitzgerald PJ (1969b) Pancreas acinar cell differentiation. II. Comparative DNA and protein synthesis of the embryonic rat pancreas and the pancreatic anlage grown in organ culture. Am J Pathol 57:489–521
Pictet LR, Clark WR, Williams RH, Rutter WJ (1972) An ultrastructural analysis of the developing embryonic pancreas. Dev Biol 29:436–467
Slot JW, Geuze JJ (1979) A morphometric study on the exocrine pancreatic cell in fasted and fed frogs. J Cell Biol 80:692–707
Uchiyama Y (1983) A histochemical study of variations in the localization of 5′-nucleotidase activity in the acinar cell of the rat exocrine pancreas over the twenty-four hour period. Cell Tissue Res 230:411–420
Uchiyama Y, Saito K (1982) A morphometric study of 24-hour variations in subcellular structures of the rat pancreatic acinar cell. Cell Tissue Res 226:609–620
Uchiyama Y, Watanabe M (1984a) Morphometric and fine structural studies of rat pancreatic acinar cells during early postnatal life. Cell Tissue Res 237:123–129
Uchiyama Y, Watanabe M (1984b) A morphometric study of the 24-hour variations in subcellular structures of pancreatic acinar cells during the periweaning period. Cell Tissue Res 237:131–138
Weibel ER (1979) Stereological methods. Practical methods for biological morphometry. Academic Press, Eondon-New York-Toronto-Sydney-San Francisco
Yamashina Y, Kawai K (1979) Cytochemical studies on the localization of 5′-nucleotidase in the acinar cells of the rat salivary glands. Histochemistry 60:255–263
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Uchiyama, Y., Watanabe, M. A morphometric study of developing pancreatic acinar cells of rats during prenatal life. Cell Tissue Res. 237, 117–122 (1984). https://doi.org/10.1007/BF00229206
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00229206