Ultrastructural analysis of some functional aspects of Xenopus laevis pancreas during development and metamorphosis

Development ◽  
1976 ◽  
Vol 36 (3) ◽  
pp. 711-724
Author(s):  
Fiorella Leone ◽  
Stefano Lambert-Gardini ◽  
Claudia Sartori ◽  
Sergio Scapin
Keyword(s):  
B Cells ◽  
Xenopus Laevis ◽  
Secretory Granules ◽  
Cell Types ◽  
C Cells ◽  
Larval Life ◽  
Exocrine Cells ◽  
Morphological Studies ◽  
A Cells ◽  
Functional Aspects

Morphological studies using both light and electron microscope were carried out with the aim of characterizing cells present in the larval and adult pancreas of Xenopus laevis. The following cell types have been seen: (1) exocrine cells, with a very well developed r.e.r. (rough endoplasmic reticulum), well defined Golgi complexes and numerous large secretory granules (A cells);(2) cells without either r.e.r. or secretory granules but with a large number of well developed mitochondria (B cells); (3) endocrine cells often clustered in the typical islets and with small membrane-coated granules showing a very dense central core surrounded by a light halo (C cells). pDuring development, the aspect is seen to change from an unorganized tissue in which the acinar structures are still not clearly visible (stage 42), to a more organized form in which the exocrine cells (A cells) are seen to be arranged around the lumen of the acinus together with some B cells. At the stages 54–56, an increasing number of acini surrounded both by A and B cells was observed. At about stage 61, large quantities of necrotic cells were seen and it became more difficult to individualize the acinar organization found in the preceding stages. Finally, there are no necrotic cells in the adult but only A, B cells which are organized in well developed acinar structures and C cells. The investigation also included a study of some pancreatic enzymes (lipase and amylase) synthesized during larval life. Lipase activity shows a peak at stage 54–56 in which the most well organized tissue of the entire larval life was observed. The activity then decreases, reaching a minimum at stage 66, after which it rapidly rises. Maximum amylase activity occurs at stage 51 after which there is a decrease, to a minimum at stage 66. The activity then remains at constant level.

Patterns of calcium localization in pancreatic endocrine cells

1976 ◽  
Vol 21 (1) ◽  
pp. 107-117
Author(s):  
M. Ravazzola ◽  
F. Malaisse-Lagae ◽  
M. Amherdt ◽  
A. Perrelet ◽  
W.J. Malaisse ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
Endocrine Cells ◽  
Secretory Granules ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Calcium Localization ◽  
A Cells ◽  
D Cells

Subcellular calcium localization in the dndocrine cells of rat pancreas was studied by the pyroantimonate precipitation technique. Calcium-containing electron-dense deposits in the endocrine cells were mostly found within secretory granules and along the plasma membrane, but their pattern of distribution in A-, B- and D-cells displayed qualitative and quantitative differences. In B-cells, numerous secretory granules contained deposits located in the halo surrounding the granule core. In A-cells, only few granules contained precipitates in their halo, whereas in D-cells, deposits were situated in the dense core of the secretory granules. Deposits along the plasma membrane occurred generally on the outer leaflet of the plasma membrane of B- and D-cells and on the inner leaflet of that of A-cells. In islets incubated at a high glucose concentration or in the presence of the calcium ionophore A23187, the number of beta granules containing precipitates was significantly increased. By contrast, only few deposits were observed in B-cells incubated in calcium-deprived medium enriched with EGTA. These findings indicate that: the pattern of calcium localization varies in different islet cell types; in B-cells the secretory granules represent one of the major stores of intracellular calcium; and that this store undergoes changes in conditions which alter insulin release.

Physiological properties of rat ventral pallidal neurons recorded intracellularly in vivo

1996 ◽  
Vol 75 (4) ◽  
pp. 1432-1443 ◽  
Author(s):  
A. Lavin ◽  
A. A. Grace
Keyword(s):  
B Cells ◽  
Nucleus Accumbens ◽  
Action Potential ◽  
Type A ◽  
C Cells ◽  
Postsynaptic Potentials ◽  
A Cells ◽  
Type C ◽  
Stimulation Of

1. The physiology of ventral pallidal (VP) cells was investigated using in vivo intracellular recording and staining techniques in adult rats. Based on electrophysiological criteria, three different types of cells were found: type A cells, which fired phasic spikes that did not exhibit a substantial afterhyperpolarization (AHP), type B cells, which exhibited a slow ramplike depolarization that preceded the short-duration action potential; the spike was followed by a prominent AHP, and type C cells, which were the only cells that fired spikes in couplets or bursts, with the spikes in a burst exhibiting a progressive increase in duration and a decrease in amplitude. These cells also exhibited a rebound low threshold spikelike event. Furthermore, 18% of the VP cells recorded exhibited a slow subthreshold oscillation of the membrane potential (< 1 Hz). 2. The response of VP cells to stimulation of fibers arising from the prefrontal cortex, nucleus accumbens, and mediodorsal thalamic nucleus (MD) was examined. In contrast to our initial predictions, all cells responded to nucleus accumbens stimulation with excitation. Type A and B cells responded to nucleus accumbens stimulation with excitation and to MD stimulation with antidromic-like responses, orthodromic excitation, or evoked inhibitory postsynaptic potentials. Only type A cells responded to prefrontal cortical stimulation. Type C cells only responded to stimulation of the nucleus accumbens, which resulted in evoked excitatory postsynaptic potentials. 3. The cells in the VP therefore can be segregated into three physiologically defined groups according to action potential discharge patterns and their response to afferent fiber stimulation.

Loss of hamster Leydig cells during regression after exposure to a short photoperiod

2018 ◽  
Vol 30 (8) ◽  
pp. 1137 ◽  
Author(s):  
E. Beltrán-Frutos ◽  
V. Seco-Rovira ◽  
J. Martínez-Hernández ◽  
C. Ferrer ◽  
L. M. Pastor
Keyword(s):  
B Cells ◽  
Leydig Cells ◽  
Light And Electron Microscopy ◽  
Type A ◽  
Nuclear Antigen ◽  
Control Group ◽  
C Cells ◽  
Type B ◽  
A Cells ◽  
Type C

The aim of the present study was to evaluate the changes that occur in hamster Leydig cells during regression. Animals were divided into control, mild regression (MR), strong regression (SR) and total regression (TR) groups. Leydig cells were characterised by light and electron microscopy. Terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) antibodies were used to detect apoptosis and proliferation respectively. Three types of Leydig cells (A, B and C) could be differentiated. Type A cells were small in size compared with Leydig cells from animals exposed to a long photoperiod, which was a result of a decreased cytoplasm and nucleus. Type B cells were even smaller than Type A cells in regression groups. Type C exhibited cytoplasm vacuolisation. The percentage of Type C cells from the control group was much lower than in the MR, SR and TR groups. (P < 0.05). In the SR and TR groups, there was a significant decrease in the percentage of Type B cells compared with the control and MR groups (P < 0.05). The total number of Leydig cells decreased during testicular regression (P < 0.05). The total number of Type A and B cells was significantly lower in the MR, SR and TR groups compared with the control group (P < 0.05). There were no significant differences in the proliferation and apoptosis index in the groups studied. The findings of the present study indicate that there are three types of Leydig cells (A, B and C) in all hamsters studied and that regression causes an increase in the number of Type C cells, so that the reduction in the number Leydig cells during the phases of regression studied must be the result of necrosis and/or necroptosis.

Electrophysiological characteristics of hamster dorsal root ganglion cells and their response to axotomy

1988 ◽  
Vol 59 (2) ◽  
pp. 408-423 ◽  
Author(s):  
S. Gurtu ◽  
P. A. Smith
Keyword(s):  
Action Potential ◽  
Dorsal Root ◽  
Cell Types ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
C Cells ◽  
A Cells ◽  
Long Duration ◽  
Delta Cells

1. The active and passive membrane properties of neurons in the lower lumbar (L6, L7) or sacral (S1) dorsal root ganglia from golden hamsters were examined in vitro by means of conventional intracellular recording techniques. Data were collected from neurons exhibiting action potentials (AP) of 70 mV or more in amplitude. 2. Cells with axonal conduction velocities (CV) greater than 20 m/s were termed fast-A-cells, those with CVs between 2.5 and 20 m/s were termed A-delta-cells, and those with CVs less than 1 m/s were termed C-cells. 3. Fast-A-cells usually exhibited short-duration APs (2.51 +/- 0.41 ms, n = 19) followed by short (less than 50 ms) afterhyperpolarizations (AHPs). C-cells usually exhibited long-duration APs (10.5 +/- 0.69 ms, n = 18) followed by long-duration AHPs (much greater than 50 ms). The characteristics of APs in A-delta-cells (AP mean duration 3.34 +/- 0.42 ms, n = 32) were intermediate between those of fast-A- and C-cells. Long AHPs (duration much greater than 50 ms) were manifest in 43.8% of A-delta-cells. 4. A time-dependent sag in hyperpolarizing electrotonic potentials (rectification) was found in 68.8% of fast-A-cells, 45.5% of A-delta-cells, and 62.5% of C-cells. 5. To examine neuronal properties 1-6 wk after transection of the sciatic nerve (axotomy), cells were reclassified as SAP (short action potential) cells and LAP (long action potential) cells. Cells in the SAP category had AP durations less than 5 ms and included all fast-A-cells and the majority of A-delta-cells. The LAP category included cells with AP durations greater than 8 ms contained only C-cells. 6. Axotomy failed to decrease the CV of LAP cells or A-delta-cells in the SAP group. The CV of LAP cells may have increased (P less than 0.05), whereas that of SAP cells was unchanged. 7. The duration of the AP and AHP of SAP cells were slightly increased (0.1 greater than P greater than 0.05), whereas AP and AHP duration of LAP cells were unchanged after axotomy. AHP amplitudes of all cell types tended to be smaller (0.1 greater than P greater than 0.05). Axotomy did not alter the resting membrane potential or reduce the incidence of rectification in any cell type. 8. Invasion of the soma by axonally evoked APs was impeded in all cell types after axotomy even though a decrease (P less than 0.05) in rheobase of SAP cells occurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of Neuroendocrine Centers on Germ and Germline Cells in Dendrobaena atheca Cernosvitov (Annelida: Lumbricidae)

2019 ◽  
Vol 36 (04) ◽  
pp. 237-246
Author(s):  
Najem Shlemoon Gorgees ◽  
Ziyad Tahseen Kiret
Keyword(s):  
Experimental Study ◽  
B Cells ◽  
Blood Capillary ◽  
C Cells ◽  
Serial Sections ◽  
Blood Capillaries ◽  
A Cells ◽  
Aldehyde Fuchsin ◽  
Staining Techniques ◽  
Histological Staining

AbstractThe aim of the present comprehensive experimental study was to reveal the effects of the removal and the regeneration of the main neuroendocrine centers in the oogonia, oocytes and trophocytes in Dendrobaena atheca. Various types of serial sections of ovaries and cephalic regions were obtained. Four histological staining techniques were employed. In controlled preparations, the neurosecretory activities of A-cells and C-cells showed correlation with cellular activities of oogonia, oocytes and trophocytes. In experimental preparations, removal of A-cells caused abnormalities in oocytes and trophocytes. The regeneration of A-cells restored vitellogenesis and repaired abnormalities. In both preparations, C-cells remained aldehyde-fuchsin (AF)-positive. B-cells and U-cells remained AF-negative. The oogonia showed continuous mitotic divisions. Regenerated A-cells appeared in week 3, increased in number, but could not stop the abnormalities, as hormones were not transported due to the lack or scarcity of blood capillaries. Therefore, abnormalities increased extremely. Then, they stopped, decreased, and were repaired due to hormonal transport via fully reconstructed blood capillary plexuses. The main conclusions are: (1) oocytes and trophocytes are controlled by A-cells, since they exhibited prominent changes during the removal and regeneration of A-cells; (2) oogonia are controlled by C-cells, as they showed correlation of activities with C-cells and were not affected by the removal and regeneration of A-cells; (3) B-cells and U-cells remained inactive; hence, they have no role in oogonia divisions and vitellogenesis; and (4) delayed hormonal effects of regenerated A-cells were due to the lack or scarcity of blood capillaries. Therefore, fully reconstructed blood capillary beds in the A-cells area are indispensable for hormonal diffusion, transport and effectivity.

Ca++-ATPase activity in the hepatopancreas cells of Oniscus asellus

1992 ◽  
Vol 50 (1) ◽  
pp. 820-821
Author(s):  
G.M. Vernon ◽  
A. Surace ◽  
R. Witkus
Keyword(s):  
B Cells ◽  
Epithelial Cell ◽  
Atpase Activity ◽  
Calcium Transport ◽  
Carcinus Maenas ◽  
Cell Types ◽  
Molt Cycle ◽  
Copper And Zinc

The hepatopancreas consists of a pair of bilobed tubules comprised of two epithelial cell types. S cells are absorptive and accumulate metals such as copper and zinc. Ca++ concentrations vary between the S and B cells and during the molt cycle. Roer and Dillaman implicated Ca++-ATPase in calcium transport during molting in Carcinus maenas. This study was undertaken to compare the localization of Ca++-ATPase activity in the S and B cells during intermolt.

The structure of the gills of the axolotl, Ambystoma mexicanum

1987 ◽  
Vol 45 ◽  
pp. 824-825
Author(s):  
Mohinder S. Jarial
Keyword(s):  
Leydig Cells ◽  
Secretory Granules ◽  
Light And Electron Microscopy ◽  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Basal Cells ◽  
Granular Cells ◽  
Gill Filaments ◽  
Mitotic Figures ◽  
Apical Membranes

The axolotl is a strictly aquatic salamander in which the larval external gills are retained throughout life. The external gills of the adult axolotl have been studied by light and electron microscopy for ultrastructural evidence of ionic transport. The thin epidermis of the gill filaments and gill stems is composed of 3 cell types: granular cells, the basal cells and a sparce population of intervening Leydig cells. The gill epidermis is devoid of muscles, and no mitotic figures were observed in any of its cells.The granular cells cover the gill surface as a continuous layer (Fig. 1, G) and contain secretory granules of different forms, located apically (Figs.1, 2, SG). Some granules are found intimately associated with the apical membrane while others fuse with it and release their contents onto the external surface (Fig. 3). The apical membranes of the granular cells exhibit microvilli which are covered by a PAS+ fuzzy coat, termed “glycocalyx” (Fig. 2, MV).

Ultrastructural Study of a differentiating human colon carcinoma cell line

1990 ◽  
Vol 48 (3) ◽  
pp. 208-209
Author(s):  
Sylvie Polak-Charcon ◽  
Mehrdad Hekmati ◽  
Yehuda Ben Shaul
Keyword(s):  
Cell Line ◽  
Morphological Changes ◽  
Secretory Granules ◽  
Human Colon ◽  
Cell Types ◽  
Culture Conditions ◽  
Morphological Evidence ◽  
Human Colon Carcinoma Cell ◽  
Colon Cell

The epithelium of normal human colon mucosa “in vivo” exhibits a gradual pattern of differentiation as undifferentiated stem cells from the base of the crypt of “lieberkuhn” rapidly divide, differentiate and migrate toward the free surface. The major differentiated cell type of the intestine observed are: absorptive cells displaying brush border, goblet cells containing mucous granules, Paneth and endocrine cells containing dense secretory granules. These different cell types are also found in the intestine of the 13-14 week old embryo.We present here morphological evidence showing that HT29, an adenocarcinoma of the human colon cell line, can differentiate into various cell types by changing the growth and culture conditions and mimic morphological changes found during development of the intestine in the human embryo.HT29 cells grown in tissue-culture dishes in DMEM and 10% FCS form at late confluence a multilayer of morphologically undifferentiated cell culture covered with irregular microvilli, and devoid of tight junctions (Figs 1-3).

LIGHT AND ELECTRON MICROSCOPICAL STUDY OF THE EFFECT OF OESTROGEN ON THE CHICKEN OVIDUCT

1967 ◽  
Vol 56 (3) ◽  
pp. 391-402 ◽  
Author(s):  
H. I. Ljungkvist
Keyword(s):  
Secretory Granules ◽  
Apical Cell ◽  
Cell Types ◽  
Microscopical Study ◽  
List Type ◽  
New Production ◽  
General Increase ◽  
Chicken Oviduct ◽  
Electron Microscopical ◽  
Aortic Perfusion

ABSTRACT Oviducts from 20 one-day old chickens were used. Ten chickens were injected subcutaneously with 0.2 mg oestradiol for 5 days, the remaining ones serving as controls. The chickens were fixed by an aortic perfusion with 2.5% glutaraldehyde in phosphate buffer, pH 7.2. The treatment with oestrogen resulted in the following changes: general increase in oviduct length and thickness, differentiation of the epithelial membrane into three cell types: basal, apical and gland cells, increase in the number of cilia in the apical cell, probably due to a new production of cilia, formation of secretory granules in the vaginal epithelium as seen by light microscopy, formation of proteinlike secretory granules in the apical cell as seen by electron microscopy, increase in protein synthesis, observed as an augmentation of the endoplasmic reticulum.

scholarly journals Anaphylactic Degranulation of Mast Cells: Focus on Compound Exocytosis

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ofir Klein ◽  
Ronit Sagi-Eisenberg
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Molecular Mechanisms ◽  
Secretory Granules ◽  
Cell Types ◽  
Secretory Cells ◽  
Regulated Exocytosis ◽  
Open Questions ◽  
Conflicting Evidence ◽  
Compound Exocytosis

Anaphylaxis is a notorious type 2 immune response which may result in a systemic response and lead to death. A precondition for the unfolding of the anaphylactic shock is the secretion of inflammatory mediators from mast cells in response to an allergen, mostly through activation of the cells via the IgE-dependent pathway. While mast cells are specialized secretory cells that can secrete through a variety of exocytic modes, the most predominant mode exerted by the mast cell during anaphylaxis is compound exocytosis—a specialized form of regulated exocytosis where secretory granules fuse to one another. Here, we review the modes of regulated exocytosis in the mast cell and focus on compound exocytosis. We review historical landmarks in the research of compound exocytosis in mast cells and the methods available for investigating compound exocytosis. We also review the molecular mechanisms reported to underlie compound exocytosis in mast cells and expand further with reviewing key findings from other cell types. Finally, we discuss the possible reasons for the mast cell to utilize compound exocytosis during anaphylaxis, the conflicting evidence in different mast cell models, and the open questions in the field which remain to be answered.

Sign in / Sign up

Export Citation Format

Share Document