MORPHOLOGICAL ASPECTS OF PROTEIN SYNTHESIS

1973 ◽  
Vol 74 (Suppl) ◽  
pp. S13-S32
Author(s):  
Bernard Droz ◽  
Monique Pisam ◽  
Monique Chrétien
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Great Majority ◽  
Cell Organelles ◽  
Differentiated Cells ◽  
Morphological Aspects ◽  
Cellular Machinery ◽  
Secretory Products

ABSTRACT Morphological aspects of protein synthesis have been mainly investigated by means of high resolution radioautography. Most of the cellular proteins are synthesized in the rough endoplasmic reticulum and on free cytoplasmic polysomes. Only few structural proteins (sedentary protein) remain in the vicinity of their sites of synthesis. The great majority of the newlysynthesized proteins move away (migratory protein). One portion of the migratory proteins is redistributed to various cell organelles and is referred to as "non exportable" protein. The migration of polypeptide chains from cytoplasmic polysomes ensures the renewal of protein in mitochondria, nucleus, and specialized membranes, in spite of the capacity of these organelles to incorporate slightly labelled amino acids. Plasma membrane precursors undergo a series of intracellular translocations and molecular complexification by adding carbohydrate groups before they reach the cell surface. Another portion of the migratory proteins, which includes secretory products, is referred to as "exportable" proteins. These exportable proteins are conveyed from the rough endoplasmic reticulum to the Golgi apparatus, then either stored and condensed in secretory granules or directly released by exocytosis. In some differentiated cells, the development of the cellular machinery for the synthesis of protein is triggered and maintained by the level of steroid hormones which controls both the quality and the quantity of secreted proteins.

The Ultrastructure and Histopathology of an Acidophil Adenoma of the Canine Adenohypophysis

1967 ◽  
Vol 4 (4) ◽  
pp. 348-365 ◽  
Author(s):  
C. C. Capen ◽  
S. L. Martin ◽  
A. Koestner
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Golgi Apparatus ◽  
Pancreatic Islets ◽  
Secretory Granules ◽  
Clinical Signs ◽  
Common Type ◽  
Secretory Cycle ◽  
Secretory Products ◽  
Space Occupying Lesion

An acidophil adenoma in a 12-year-old spayed boxer dog resulted in clinical signs related to a space-occupying lesion of the hypophysis. There were two types of acidophils, as determined ultrastructurally, within the adenoma. The predominating type was interpreted to be in the storage phase of the secretory cycle as the cytoplasm was densely granulated and the organelles concerned with protein synthesis and packaging of secretory products were poorly developed. The second, less common type contained few secretory granules, had a well developed endoplasmic reticulum and Golgi apparatus, and was interpreted to be secretorily active. The secretory granules of the neoplastic acidophils were large (420 m μ), uniformly electron-dense, and had a narrow submembranous space. An adenoma of the pancreatic islets was also present.

Functional Chromophobe Adenomas of the Canine Adenohypophysis

1967 ◽  
Vol 4 (4) ◽  
pp. 326-347 ◽  
Author(s):  
C. C. Capen ◽  
A. Koestner
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Secretory Granules ◽  
Clinical Signs ◽  
Secretory Activity ◽  
Electron Microscopic ◽  
Active Secretion ◽  
Neoplastic Cells ◽  
Definite Evidence ◽  
Secretory Products

Chromophobe adenomas from 8 dogs with clinical signs and lesions of hyperadrenocorticism (Cushing's-like disease) were selected for electron microscopic study in order to establish a morphologic basis for active secretion by the neoplastic cells. At the level of ultrastructure there was definite evidence of secretory activity and the organelles concerned with protein synthesis (endoplasmic reticulum) and packaging of secretory products (Golgi apparatus) were well developed. Although the numerous secretory granules present varied in electron density and in size, the most frequently encountered granule measured 170 m μ in diameter. The secretory granules of the neoplastic cells differed from those found within acidophils and basophils of the canine hypophysis. Based on these findings it was concluded that the cells comprising these chromophobe adenomas were actively secreting corticotrophs of the pituitary gland.

scholarly journals DEVELOPMENT OF ENDOGENOUS PEROXIDASE IN FETAL RAT SUBMANDIBULAR GLAND

1973 ◽  
Vol 21 (1) ◽  
pp. 42-50 ◽  
Author(s):  
SHOHEI YAMASHINA ◽  
TIBOR BARKA
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Submandibular Gland ◽  
Rough Endoplasmic Reticulum ◽  
Peroxidase Activity ◽  
Secretory Granules ◽  
Prenatal Development ◽  
Reaction Products ◽  
Cell Type ◽  
Endogenous Peroxidase

The prenatal development of endogenous peroxidase activity in the submandibular gland of rat was investigated by means of the diaminobenzidine-H2O2 histochemical method. The submandibular gland of a 16-day-old fetus was composed of cords of uniform, undifferentiated cells which contained no secretory granules and revealed no peroxidase activity. Peroxidase activity first appeared at the 17th day of gestation in the cisternae of the rough endoplasmic reticulum and nuclear envelope in a few cells. At the 18th day of gestation cells which exhibited reaction products in the rough endoplasmic reticulum and nuclear envelope also contained secretory granules with a strong peroxidase activity. During the last days of gestation the number of peroxidase positive cells, which contained numerous secretory granules, increased. The peroxidase-containing cells are the immediate precursors of the proacinar cells of early postnatal stages. During the same time period, when the peroxidase-containing cells differentiated, a second cell type also differentiated in the cellular cords. The development of this cell type was marked by the appearance of secretory granules stainable with toluidine blue. Through the prenatal development, this cell type revealed no peroxidase activity and was identified with the terminal tubule cell of the newborn. The morphologic and cytochemical findings indicate that terminal tubule cells and proacinar cells are committed cells; the former differentiate toward 2nd order intercalated duct cells and the latter transform to mature acinar cells.

scholarly journals THE ELABORATION OF PROTEIN AND CARBOHYDRATE BY RAT PARATHYROID CELLS AS REVEALED BY ELECTRON MICROSCOPE RADIOAUTOGRAPHY

1971 ◽  
Vol 51 (3) ◽  
pp. 596-610 ◽  
Author(s):  
K. Nakagami ◽  
H. Warshawsky ◽  
C. P. Leblond
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Intravenous Injection ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Glycoprotein Precursor ◽  
Secretion Granules ◽  
And Migration ◽  
The One ◽  
Membrane Cell

The parathyroid glands of young rats were radioautographed after a single injection of the protein precursor tyrosine-3H in the hope of identifying the sites of synthesis and migration of newly formed protein in the gland cells. The same procedure was used after injection of the glycoprotein precursor galactose-3H. As early as 2 min after intravenous injection of tyrosine-3H, the label was mainly found in the rough endoplasmic reticulum suggesting that cisternal ribosomes are sites of protein synthesis. By 5 and 10 min, much of the label had migrated from the rough endoplasmic reticulum into the Golgi apparatus. By 20 and 30 min, some label had migrated from there into secretory granules. By 45 min and 1 hr, the label content of the cell had decreased, indicating release of labeled material outside the cell. At 2 min after intravenous injection of galactose-3H, the label was mainly present in the Golgi apparatus, where presumably galactose is taken up into glycoprotein. By 10 min, some label appeared in secretion granules and by 30 min release of the material to the outside of the cell was under way. In conclusion, it is likely that the tyrosine-labeled protein material consists mainly of the parathyroid hormone. The galactose-labeled carbohydrate material would be either associated with the hormone in the cell or be part of a distinct glycoprotein which may be the one present on the outer surface of the plasma membrane (cell coat).

Altered labelling of the cell surface and intracellular organelles with [3H]mannose in enucleated amoebae

1984 ◽  
Vol 68 (1) ◽  
pp. 83-94
Author(s):  
C.J. Flickinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Cell Surface ◽  
Rough Endoplasmic Reticulum ◽  
Intracellular Transport ◽  
Cell Organelles ◽  
Intracellular Organelles ◽  
And Control ◽  
Kinetics Of ◽  
Heavy Labelling

The production, transport, and disposition of material labelled with [3H]mannose were studied in microsurgically enucleated and control amoebae. Cells were injected with the precursor and samples were prepared for electron-microscope radioautography at intervals, up to 24 h later. Control cells showed heavy labelling of the rough endoplasmic reticulum and the Golgi apparatus at early intervals after injection. Later, labelling of groups of small vesicles increased, and the percentage of grains over the cell surface peaked 12 h after administration of the precursor. Two major changes were detected in enucleate amoebae. First, the kinetics of labelling of cell organelles with [3H]mannose were altered in the absence of the nucleus. The Golgi apparatus and cell surface both displayed maximal labelling at later intervals in enucleates, and the percentage of grains over the rough endoplasmic reticulum varied less with time in enucleated than in control cells. Second, the distribution of radioactivity was altered. A greater percentage of grains was associated with lysosomes in enucleates than in control cells. The change in the kinetics of labelling of the endoplasmic reticulum, Golgi apparatus and cell surface indicates that intracellular transport of surface material was slower in the absence of the nucleus. It is suggested that this is related to the decreased motility of enucleate cells.

scholarly journals ULTRASTRUCTURAL VARIATIONS IN N,N'-BIS(4-AMINOPHENYL)-N,N'-DIMETHYLETHYLENEDIAMINE (BED) OXIDASE LOCALIZATION IN RAT LIVER AND PAROTID GLAND WITH VARIATION IN LENGTH OF FIXATION

1972 ◽  
Vol 20 (12) ◽  
pp. 1024-1030 ◽  
Author(s):  
W. ALLEN SHANNON ◽  
ARNOLD M. SELIGMAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Parotid Gland ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Terminal Oxidase ◽  
Outer Compartment ◽  
Fixation Reaction

The localization and reactivity of a terminal oxidase which oxidizes N,N'-bis(4-amino-phenyl)-N,N'-dimethylethylenediamine (BED) were studied in rat liver and parotid gland after varying the concentration of formaldehyde fixative and the length of fixation. Reaction product was observed in mitochondrial outer compartments, smooth elements of rough endoplasmic reticulum, some Golgi lamellae, perinuclear membranes and cytoplasmic membranous structures often associated with mitochondria. A reaction also occurred in the limiting membrane and, to some degree, in the material comprising the secretory granules of the parotid. The reaction in the mitochondrial outer compartment was extremely formaldehyde-sensitive. Controls in which diaminobenzidine (DAB) was substituted for BED showed reaction only in mitochondrial cristae and outer compartments, whereas controls without either reagent showed no reactivity.

Ultrastructure of the Genital Duct Epithelium of the Male Port Jackson Shark, Heterodontus-Portusjacksoni

1992 ◽  
Vol 40 (3) ◽  
pp. 257 ◽  
Author(s):  
RC Jones ◽  
M Lin
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Close Association ◽  
Ciliated Cells ◽  
Dense Bodies ◽  
Ductuli Efferentes ◽  
Apical Vesicles

The genital ducts of Heterodontus portusjacksoni are lined by a ciliated epithelium. In the ductuli efferentes the epithelium is low and contains numerous intraepithelial leucocytes which often contain large dense bodies. All epithelial cells are ciliated and are characterised by apical vesicles, vacuoles and glycogen granules, some rough endoplasmic reticulum, dense bodies and lipid droplets, and a Golgi apparatus. The initial segment of the ductus epididymidis is lined by a very tall epithelium of ciliated and non-ciliated cells. The non-ciliated cells contain numerous apical vesicles, a large Golgi apparatus and numerous mitochondria and secretory granules in close association with an extensive endoplasmic reticulum. The terminal segment of the ductus epididymidis is lined by a low columnar epithelium. A proximal region, occupying part of the head of the epididymis, is similar to the epithelium in the ductuli efferentes. Distally, all the epithelial cells are ciliated. They are characterised by considerable dilated endoplasmic reticulum, a Golgi apparatus, apical vesicles, and numerous mitochondria and secretory granules. The secretory tubules of Leydig's glands are lined by a very tall epithelium with non-ciliated cells containing extensive, dilated, rough endoplasmic reticulum, a large Golgi apparatus, and numerous mitochondria and secretory granules. The significance of the structural differentiation of the duct is discussed in relation to the evolution of the mammalian epididymis.

The human fetal pituitary: An ultrastructural analysis

1983 ◽  
Vol 41 ◽  
pp. 574-575
Author(s):  
S. L. Asa ◽  
K. Kovacs ◽  
E. Horvath ◽  
F. A. Laszlo ◽  
I. Domokos
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Type I ◽  
Hormone Production ◽  
Glycoprotein Hormone ◽  
Poorly Differentiated ◽  
Rathke's Cleft ◽  
Flocculent Material ◽  
Cytoplasmic Glycogen

An ultrastructural study was performed on 25 human fetal pituitaries to document the development of cell differentiation and hormone production in the adenohypophysis.At 5 weeks' gestation, Rathke's cleft was lined by columnar epithelium 3-4 cells deep (Fig. 1). The cells were poorly differentiated, with abundant cytoplasmic glycogen, numerous free ribosomes and occasional secretory granules. Terminal bars were formed on the lateral cell surfaces near the luminal surface of Rathke's cleft; desmosomes formed junctions between cells.By 6 weeks' gestation, cells resembling corticotrophs were identified (Fig. 2). They contained moderately developed, rough endoplasmic reticulum and numerous secretory granules of variable size, shape and electron density. In 8-week-old fetuses, type I microfilaments were found in those cells. Welldifferentiated somatotrophs were seen in the adenohypophyses of 8-9-week-old fetuses. They contained scattered profiles of rough-surfaced endoplasmic reticulum and spherical, evenly electron dense secretory granules, measuring 300-600 nm in diameter. Cells with dilated rough endoplasmic reticulum containing flocculent material and small, dense, round secretory granules with peripheral electron lucent halos were seen in the adenohypophysis of a 14-week-old fetus; these features are characteristic of the glycoprotein hormone cell line. Typical prolactin cells were not recognizable before 23 weeks' gestation.

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