scholarly journals The Fine Structure of Blastema Cells and Differentiating Cartilage Cells in Regenerating Limbs of Amblystoma Larvae

1958 ◽  
Vol 4 (5) ◽  
pp. 583-592 ◽  
Author(s):  
Elizabeth D. Hay
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Cell Types ◽  
Ground Substance ◽  
High Concentration ◽  
Blastema Cell ◽  
Undifferentiated Cells ◽  
Abundant Cytoplasm ◽  
Cartilage Cells ◽  
Cell Changes

Regenerating forelimbs of larval salamanders, Amblystoma punctatum, were fixed in OsO4 at various intervals after amputation and were sectioned for study with the electron microscope. The dedifferentiated cells comprising the early blastema were found to have a fine structure similar to that of other undifferentiated cells and to have lost all of the identifying morphological features of their tissues of origin. The cytoplasm of such cells is characterized by numerous free ribonucleoprotein granules and a discontinuous vesicular endoplasmic reticulum. The cells have more abundant cytoplasm and are in closer contact with each other than was previously realized. The layer of condensed ground substance investing most differentiated cell types is lacking. After a period of rapid cell division, the morphology of the blastema cell changes. Cytoplasm is now sparse and contains a high concentration of free ribonucleoprotein granules, but little endoplasmic reticulum. The differentiating cartilage cell, however, develops an extensive, highly organized endoplasmic reticulum and the Golgi apparatus also appears to become more highly differentiated and more extensive at this time. Small vesicles appear throughout the cytoplasm at the time the new cisternae originate and may contribute to their formation. These and other changes in the cytoplasmic organelles are discussed.

scholarly journals A SMALL PARTICULATE COMPONENT OF THE CYTOPLASM

1955 ◽  
Vol 1 (1) ◽  
pp. 59-68 ◽  
Author(s):  
George E. Palade
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Types ◽  
High Density ◽  
Ground Substance ◽  
Degree Of Differentiation ◽  
High Degree

A particulate component of small dimensions (100 to 150 A) and high density is described in the ground substance of the cytoplasm of mammalian and avian cells. In many cell types that seem to have in common a high degree of differentiation, the new component is preferentially associated with the membrane of the endoplasmic reticulum; whereas in other cell types, characterized by rapid proliferation, it occurs more or less freely distributed in the ground substance of the cytoplasm. In the Discussion an attempt is made to integrate the observations presented in this paper with the already available cytological, histochemical, and cytochemical information.

Effect of thyroxine on the ultrastructure of the hypophyseal proximal pars distalis in Tilapia zillii

1975 ◽  
Vol 53 (6) ◽  
pp. 686-690 ◽  
Author(s):  
John F. Leatherland ◽  
Mohamed Hyder
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Cell Types ◽  
Pars Distalis ◽  
Tilapia Zillii ◽  
Thyroid Axis ◽  
And Control ◽  
Granule Release

The effects of exogenous L-thyroxine on the fine structure of the proximal pars distalis cells were examined in Tilapia zillii. In thyroxine-treated animals the thyrotrophic cells appeared marginally smaller and less active whereas the somatotrophs appeared markedly more active, with increased endoplasmic reticulum, larger mitochondria, and more granule release when compared with the same cell types in control animals. The gonadotrophs were similar in appearance in both thyroxine-treated and control groups.The possible interrelated activity of the somatotrophs and the TSH–thyroid axis is discussed.

scholarly journals Isolation, Culture, and Differentiation of Blastema Cells from the Regenerating Caudal Fin of Zebrafish

Fishes ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 6 ◽  
Author(s):  
Parameswaran Vijayakumar ◽  
M. Leonor Cancela ◽  
Vincent Laizé
Keyword(s):  
Cell Differentiation ◽  
Primary Cultures ◽  
Cell Types ◽  
Blastema Cell ◽  
Caudal Fin ◽  
Epimorphic Regeneration ◽  
All Trans Retinoic Acid ◽  
Undifferentiated Cells ◽  
Wound Epidermis ◽  
Cost Efficient

The caudal fin of teleost fish has become an excellent system for investigating the mechanisms of epimorphic regeneration. Upon amputation of the caudal fin, a mass of undifferentiated cells, called blastema, proliferate beneath the wound-epidermis and differentiate into various cell types to faithfully restore the missing fin structures. Here we describe a protocol that can be used to isolate and culture blastema cells from zebrafish. Primary cultures were initiated from 36 h post-amputation (hpa) blastema and optimal cell growth was achieved using L-15 medium supplemented with 5% fetal bovine serum in plates either coated with fibronectin or uncoated. After seeding, zebrafish blastema cells formed a uniform culture and exhibited polygonal shapes with prominent nucleus, while various cell types were also observed after few days in culture indicating cell differentiation. Upon treatment with all-trans retinoic acid, zebrafish blastema cells differentiated into neuron-like and oligodendritic-like cells. Immunocytochemistry data also revealed the presence of mesenchymal and neuronal cells. The availability of blastema cell cultures could contribute to a better understanding of epimorphic regeneration by providing a mean to investigate the mechanisms underlying blastema cell differentiation. Furthermore, this protocol is simple, rapid, and cost-efficient, and can be virtually applied to the development of any fish blastema cell culture.

scholarly journals Stereological analysis of hepatic fine structure in the Fischer 344 rat. Influence of sublobular location and animal age.

1978 ◽  
Vol 78 (2) ◽  
pp. 319-337 ◽  
Author(s):  
D L Schmucker ◽  
J S Mooney ◽  
A L Jones
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Surface Area ◽  
Structural Parameters ◽  
Male Rats ◽  
Ground Substance ◽  
Stereological Analysis ◽  
Fischer 344 ◽  
Age Related ◽  
Old Rats

Stereological analysis of hepatic fine structure in Fischer 344 male rats at 1, 6, 10, 16, 20, 25, and 30 mo of age revealed differences in the amounts and distributions of hepatocellular organelles as a function of sublobular location or animal age. Between 1 and 16 mo of age, both the centrolobular and periportal hepatocytes increased in volume by 65 and 35%, respectively. Subsequently, the cell volumes declined until the hepatocytes of 30-mo-old rats approached the size of those found in the youngest animals. Regardless of animal age, the centrolobular cells were consistently larger than the corresponding periportal hepatocytes. The cytoplasmic and ground substance compartments reflected similar changes in their volumes, although there was no significant alteration in the nuclear volume. The volumes of the mitochondrial and microbody compartments increased and decreased concomitant with the changes in average hepatocyte size. Both lobular zones in the 30-mo-old rats contained significantly smaller relative volumes of mitochondria than similar parenchyma in 16-mo-old animals. The volume density of the dense bodies (lysosomes) increased markedly in both lobular zones between 1 and 30 mo of age, confirming reports of an age-dependent increase in this organelle. The surface area of the endoplasmic reticulum in the centrolobular and periportal hepatocytes reached its maximum level in the 10-mo-old rats and subsequently declined to amounts which approximated those measured in the 1-mo-old animals. This age-related loss of intracellular membrane is attributable to a significant reduction in the surface area of the smooth-surfaced endoplasmic reticulum (SER) in animals beyond 16 mo of age. The amount of rough-surfaced endoplasmic reticulum (RER) in the periportal parenchymal cells was unaffected by aging, but the centrolobular hepatocytes of 30-mo-old animals contained 90% more RER than similar cells in the youngest rats. The centrolobular parenchyma contained more SER and the portal zones more RER throughout the age span studied. These quantitative data suggest that (a) certain hepatic fine structural parameters undergo marked changes as a function of animal age, (b) there exists a gradient in hepatocellular fine structure across the entire liver lobule, and (c) there are remarkable similarities in hepatocyte ultrastructure between very young and senescent animals, including cell size and the amount of SER.

Differentiation of Neurosensory Cells in Hydra

1969 ◽  
Vol 5 (3) ◽  
pp. 699-726
Author(s):  
LOWELL E. DAVIS
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Electron Microscope ◽  
Basal Body ◽  
Neurosecretory Cells ◽  
Nerve Cells ◽  
Granular Endoplasmic Reticulum ◽  
Structural Variations ◽  
Intercellular Bridges ◽  
Undifferentiated Cells

The differentiation of neurosensory cells in Hydra has been studied at the level of the electron microscope. These cells arise from interstitial cells (undifferentiated cells) and not from pre-existing nerve cells. Furthermore, there is no evidence to suggest that neurosensory cells represent a stage in the development of other nerve cells, i.e. ganglionic and neurosecretory cells. Major cytoplasmic changes in fine structure during differentiation include development of a cilium and associated structures (basal body, basal plate, rootlets), development of microtubules and at least two neurites, increase in Golgi lamellae and formation of dense droplets typical of neurosecretory droplets, structural variations in mitochondria and a decrease in the number of ribosomes. Granular endoplasmic reticulum is characteristically poorly developed in all stages of differentiation, including the mature neurosensory cell. Nuclear and nucleolar changes also occur during differentiation but these are less dramatic than the cytoplasmic events. The possibility of neurosensory cells being bi- or multiciliated and the presence of intercellular bridges between these cells are considered. The function of neurosensory cells is discussed briefly in relation to the function of the cilium and neurosecretory droplets.

scholarly journals The Fine Structure of the Wheat Scutellum Before Germination

1972 ◽  
Vol 25 (1) ◽  
pp. 9 ◽  
Author(s):  
JG Swift ◽  
TP O'brien
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Coat Protein ◽  
Storage Protein ◽  
Cell Walls ◽  
Lipid Droplets ◽  
Light And Electron Microscopy ◽  
Ground Substance ◽  
Nuclear Chromatin

The structure of the cells of the scutellar epithelium and parenchyma is described and illustrated by light and electron microscopy of air-dry grains and compared with that seen in grains soaked for 3 hr. In the air-dry state, nuclear chromatin is strongly aggregated, mitochondria and plastids appear to be intact, endoplasmic reticulum is present but not abundant, and dictyosomes cannot be readily identified. The ground substance contains an abundance of free ribosomes which appear to coat protein bodies, lipid droplets, and mitochondria. In material soaked only for 3 hr, endoplasmic reticulum and dictyosomes are apparent, the nuclear chromatin has dispersed, and some mobilization of storage protein appears to have begun in the scutellar epithelium. No differences in fine structure of other organelles or in the cell walls could be detected.

scholarly journals The Fine Structure of the Parathyroid Gland

1958 ◽  
Vol 4 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Jerry Steven Trier
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Connective Tissue ◽  
Light Microscope ◽  
Parenchymal Cell ◽  
Cell Types ◽  
Perivascular Spaces ◽  
Chief Cells ◽  
Golgi Bodies ◽  
Endocrine Tissues

The fine structure of the parathyroid of the macaque is described, and is correlated with classical parathyroid cytology as seen in the light microscope. The two parenchymal cell types, the chief cells and the oxyphil cells, have been recognized in electron micrographs. The chief cells contain within their cytoplasm mitochondria, endoplasmic reticulum, and Golgi bodies similar to those found in other endocrine tissues as well as frequent PAS-positive granules. The juxtanuclear body of the light microscopists is identified with stacks of parallel lamellar elements of the endoplasmic reticulum of the ergastoplasmic or granular type. Oxyphil cells are characterized by juxtanuclear bodies and by numerous mitochondria found throughout their cytoplasm. Puzzling lamellar whorls are described in the cytoplasm of some oxyphil cells. The endothelium of parathyroid capillaries is extremely thin in some areas and contains numerous fenestrations as well as an extensive system of vesicles. The possible significance of these structures is discussed. The connective tissue elements found in the perivascular spaces of macaque parathyroid are described.

The fine structure of RNA-storing archaeocytes from gemmules of fresh-water sponges

1965 ◽  
Vol s3-106 (73) ◽  
pp. 99-114
Author(s):  
AUGUST RUTHMANN
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Fresh Water ◽  
Structural Integrity ◽  
Structural Aspect ◽  
Ground Substance ◽  
Annulate Lamellae ◽  
Golgi Bodies ◽  
High Concentrations ◽  
Cytoplasmic Ground Substance

Gemmules of fresh-water sponges contain about 500 binucleated cells (‘archaeocytes’) which are loaded with reserve substances including ribonucleoprotein, acidophilic proteins, lipids, and polysaccharides. These substances are utilized during the early phase of histogenesis after germination of the gemmules. Apart from the presence of reserve bodies, the basic fine structure of metabolically inactive archaeocytes within the closed system of a gemmule is not fundamentally different from actively metabolizing cells of rapidly growing tissues. In particular, ribosomes, endoplasmic reticulum, mitochondria, Golgi bodies, and RNA-containing nucleoli are present during inactivity as well as after germination and resumption of growth and synthesis. Changes in cellular fine structure after germination include an increased density of the cytoplasmic ground substance, the appearance of small vesicles in the vicinity of the Golgi bodies and of annulate lamellae and a large, cylindrical centriole near the nuclear envelope. Two general conclusions are drawn from these results. Neither the ultra-structural aspect of a cell nor the presence of high concentrations of RNA in cytoplasm and nucleolus is a valid indication of cellular activity or inactivity. The persistence of Golgi bodies and endoplasmic reticulum through long periods of inactivity shows that their structural integrity is not dependent upon continuous energy input, although these intracellular membrane systems are undoubtedly dynamic structures in metabolically active cells.

THE ULTRASTRUCTURE OF THE ACCESSORY SEX ORGANS OF THE MALE RAT

1973 ◽  
Vol 74 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Erik Dahl ◽  
Kjell J. Tveter ◽  
Åsmund Kjaerheim
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Secretory Granules ◽  
Electron Microscopic Examination ◽  
Cell Types ◽  
Male Rat ◽  
Electron Microscopic ◽  
Genital Complex ◽  
Accessory Sex Organs ◽  
Complete Regeneration

ABSTRACT The present paper describes the fine structure of the accessory sex organs of the male rat as seen after stimulation with testosterone administered to castrated adults as well as infantile rats. Electron microscopic examination of the testosterone-treated castrated animals revealed an almost complete regeneration of the epithelial cells in all the organs, with a well developed Golgi area, a well developed rough endoplasmic reticulum and an increased number of secretory granules. The results obtained are discussed in relation to the biochemical data, and it is concluded that the various cell types of the accessory genital complex react in a fundamentally similar manner to the administration of testosterone.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

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