Introducing a new model for studying retinal detachment/replacement: an electron microscopic study

Retinal detachment, separation of the neurosensory retina from the underlying retinal pigment epithelium, is a sight threatening condition that is considered one of the few ocular emergencies. In the current experiment, electron microscopic study of the retina of toad buffo marienes was done to evaluate the morphological changes due to retinal detachment and the possibility of spontaneous reattachment and to confirm the possibility of the use of the toad retina as a model for retinal detachment studies in mammals. The study focused on the retinal pigment epithelium and the outer segment of the neural retina. The retinal pigment epithelium of the control retina expressed the main features of the cells including the apical processes, the melanin granules and the phagosomes. The apical processes were firmly interdigitating with the neural retina outer segment and the melanin granules appear near the apical part of the cells. The outer segment of the neural retina appeared with parallel plates of flattened membranous desks. At 30 minutes after retinal detachment, a subretinal space appeared and the interdigitation between the processes of retinal pigment epithelium and the outer segment of the neural retina was lost. Two hours after retinal detachment, no continuity appeared between the retinal pigment epithelium and the outer segment of the neural retina. At 5 and 10 hours after retinal detachment, the interdigitation between the retinal pigment epithelium and the outer segment of the neural retina was restored. The tight junctions between different neural retina outer segments appeared to be not affected. In the current experiment, a simple model for experimental study of retinal pigment epithelium, neural retina and retinal detachment has been introduced. Due to the ultrastructural similarities of toad retinal pigment epithelium with that of mammals, the toad can serve as an excellent model for the study of retinal detachment/reattachment and their cellular and molecular mechanisms

effect of oral administration of formadehyde on the liver of the albino rat: an electron microscopic study

Formaldehyde is an electrophilic molecule able to crosslink DNA and protein which leads to its claim for cytotoxicity and carcinogenicity. It is used as a disinfectant, antiseptic, in the manufacture of plastic and resins and in cheese production to give the cheese the firm consistency. Previous studies have focused on the direct acute harmful effects of formaldehyde on the skin, eye and respiratory system while less efforts have been made to evaluate its possible harmful effects on different body systems after long period of oral administration of a reasonably low dose. The possible toxic effect of formalin [40% solution of formaldehyde in water] on the ultrastructure of the liver of albino rat has been evaluated in the current study as the liver is the main site for formaldehyde metabolism in the body. Two groups of albino rats of 10 animals each were used where the first group received 25 mg/kg/day of formalin orally by gavages for three weeks while the second group received an equivalent volume of distilled water orally by gavages and used as control. The results showed that formalin markedly affected liver ultrastructure at the levels of hepatocytes, intrahepatic biliary system and portal tracts. Hepatocytes showed nuclear degeneration, mitochondrial degeneration, shortening and fragmentation of rough endoplasmic reticulum and peroxisomal alteration. Intrahepatic biliary system affection appeared in the form of dilatation of the bile canaliculi with shortening or complete loss of microvilli and degeneration of the covering epithelium of bile ductules. Infiltration of the portal tracts with neutrophils, lymphocytes and plasma cells were also observed which indicated an inflammatory process in the portal tract. The results, which suggest a marked toxic effect of formalin on the liver after oral administration of small doses for a long period, have been discussed. A recommendation for properly avoiding the harmful effect of this chemical substance has been offered especially the proper application of its prohibition in cheese and dairy production

Histogenesis of human renal cell carcinoma using electron microscopy and immunohistochemical techniques

Determination of the tissue of origin of either normal or abnormal tissues in the body is usually reforred as histogenesis. Electron microscopy and immunohistochemical techniques have been used in the current experiment for histogenesis of one of the most agonizing kidney diseases, namely the renal cell carcinoma.40 kidneys were subjected after radical nephrectomy to immunohistochemical detection of the presence of intermediate filament cytokeratin, which is normally expressed in epithelial tissue and intermediate filament vimentin, which is normally expressed in mesenchymal non-myogenic cells. The kidneys were also examined by electron microscopy for detection of ultrastructure features that help determination the tissue of origin. From each kidney, two specimens were taken, one from the diseased area and another from far beyond the safety margin to serve as control. Additional control specimens were taken from nephrectomized kidneys for traumatic causes. Immunohistochemical study of the control specimens revealed expression of vimentin in the glomerular capillaries and expression of cytokeratin along the tubular epithelium. In cases of renal cell carcinoma, cytokeratin was expressed alone in 45% of cases, vimentin was expressed alone in 10% of cases and coexpression of both cytokeratin and vimentin was observed in 40% of cases while 5% of cases showed no expression. Electron microscopic study of the control specimens revealed the basic ultrastructure of the normal kidneys while the ultrastructure study of the diseased specimens revealed the basic features of the tumor. Expression of desmosomes was observed in almost all tumor specimens. The expression of the vimentin in some cases either alone or with cytokeratin was interpreted as a change in the characters of some tumor cells which indicates the need for additional techniques in such cases to get the proper interpretation. The prevalence of the expression of cytokeratin and the persistence existence of desmosomes indicate the epithelial origin of the tumor. The result of the current study is very beneficial for determining the line of therapy and follow up the patients. Moreover, it confirms the power of combined use of both immunohistochemistry and electron microscopy in histogenesis of any tissue with undetermined origin

Electron microscopic study of the effect of Aflatoxin B1 on the kidney: an experimental study

Aflatoxin Bl is the most toxic among aflatoxins which are secondary metabolites produced by Aspergillus parasiticus and Aspergillus flavus. It is best known as hepatocarcinogen although other organs affection was found. To study the possible toxic effect of aflatoxin Bl on the kidney at the ultrastructural level, six groups of adult ad-libidum albino rats were used. The first group served as control and the second, third, fourth, fifth and sixth groups received a single oral dose of aflatoxin Bl by gavage at doses of 50, 100, 150, 200 and 250 micro gm/kg body weight respectively. Electron microscopic changes were only discovered in the last group. Cortical changes included cellular degenerative changes indicated by fragmented nuclei and infiltration with inflammatory cells namely lymphocytes and neutrophils. Proliferation of mesangeal cells was also noted. Changes in proximal convoluted tubules included degenerative changes in the epithelial lining cells manifested by pyknotic nuclei and mitochondrial degeneration with swollen and disrupted cristae. Lysosomes and cytoplasmic vacuoles appeared increased. Apical degeneration with partial loss of microvilli was noted and the cellular contents were partially evacuated into the lumen. Changes in the distal convoluted tubules included apical degeneration of epithelial lining cells and degenerative changes in some basal mitochondria. The results suggest the toxic effect of aflatoxin Bl on the kidney. Recommendation of proper eradication of Aspergillus parasiticus and Aspergillus flavus and their toxins from all sources of the food was offered

Electron microscopic study of the effect of theophylline on the myocardium of albino rat

Theophylline intoxication is one of the most common causes of both acute toxicity and chronic unintentional overmedication. The possible toxic effects of theophylline on the ultrastructure of the myocardium have been studied in this current experiment. Two groups of male adult albino rats were used in this study. The first group served as control. The rats of the second group received intraperitoneal injection of theophylline at a dose of 100 mg/kg/day for 5 days. All animals were sacrificed in the 6th day and parts of the myocardium were quickly removed and processed for electron microscopic study. The results showed that theophylline led to multiple ultrastructural changes of the myocardium in the form of myofibrillar degeneration, mitochondrial degeneration, intracellular fluid accumulation and intercalated discs degeneration. Myofibrillar degeneration, mitochondrial degeneration and intracellular fluid accumulation could be considered as ischemic changes. The destruction of the intercalated discs indicates dysfunction in both cardiomyocytes conductivity and contractility. It is concluded that theophylline, the worldwide used bronchodilator, can cause damage to the myocardium at subcellular level. This leads to the recommendation of respecting different factors which can increase the drug safety including limitation of its use only when indicated, proper calculation of its dose and avoiding drug-drug interaction which may increase the possibility of theophylline toxicity

Development of uteroplacental vasuclature, granulated metrial gland cells and trophoblasts in the uterine wall of the mouse during pregnancy

The development of the uteroplacental vasculature was studied by Indian ink injection method. The non-pregnant [estrus] endometrium was supplied by radial and terminal arteries. On day 5 of pregnancy the radial arteries became spiral arteries. All these changes appeared as an indication for the increased uterine blood volume. In this early five days interval of rapid development prior to blastocyst attachment, the endometrium underwent a decidual reaction by transforming its fusiform stromal cells into large polyhedral cells [decidual cells]. Ultrastructurally, their processes appeared to penetrate the basement membranes of the uterine epithelial cells and might aid in its disintegration. In the subsequent stages [days 6-8 of pregnancy] during the initial stages of invasion of the endometrial stroma by the embryo, most trophoblastic cells surrounding the blastocyst were flat [or roughly low cuboidal]. As pregnancy proceeded [on day 8], the area occupied by the trophoblasts became larger and some of these cells became giant. This was associated with an activation of the giant cells and their aquistion of invasive behavior, to complete the process of implantation previously experienced by decidual cells. From day 8 to day 14, the products of conception continued to enlarge at the expence of th surrounding endometrium. On day 8 erosion of endometrial blood vessels became more extensive. The outward growth of the trophoblasts from the trophoblastic shell forming primary villi. When the latter villi were invaded by mesenchymal connective tissue and branches of the umbilical arteries, they were termed chorionic villi. This was the anatomical bases for the achievement of the labyrinthine hemochorial placenta which increases in size in the subsequent stages [11-14 days]. It was considered the first step towards establishing the uteroplacental circulation on which the growth of the embryo will later depend. Numerous GMG cells characterized by their PAS positive cytoplasmic granules were found to differentiate in the deciduas basalis and metrial glands of the uterine wall during the first half of pregnancy [till day 8]. By day 8 and the subsequent stages of pregnancy some of the GMG cells were lying adjacent to the labyrinthine placenta

Structural changes of lung alveoli and alveolar macrophages of the albino rat following invivo and invitro exposure to sodium fluoride

In this work both the effect of ingestion of sodium fluoride [NaF] for three months on the ultrastructure of lung alveoli and, the effect of NaF on macrophages isolated from the lung and cultured invitro were studied. The results revealed that ingestion of NaF led to distortion of alveolar epithelia, thickening of the blood air barrier and interstitial edema due to transudation of fluid from the dilated blood capillaries into the interstitial spaces. Also, Pneumocyte type II [P2] were degenerated and their secretory granules showing amellar structure [lamellar bodies] were decreased. This was an indication of increased surfactant secretion without a corresponding increase in the rate of synthesis. There was increase of pulmonary alveolar macrophages [PAM] and most of them showed heterogeneity of their cytoplasmic inclusions mainly in the form of heterophagic vacuoles, Most of PAM showed apoptotic changes [in the form of nuclear pyknosis or even fragmentation of the nuclei] after NaF ingestion and after invitro culture with NaF, From this work it could be concluded that NaF ingestion caused damage of the lung alveoli. Also, NaF particles acted as a stimulating factor for the proliferation of macrophages to engulf these foreign particles. Eventually the toxicity of fluoride leads to apoptosis of macrophages. So it could be concluded that NaF acts as an environmental toxicant that carries the risk of occurance of pulmonary dysfunction

Light and electron microscopic study of liver glycogen heterogeneity

Seven ad-libidum fed rats and seven overnight fasted rats where used in this experiment. Their livers where subjected to enzymatic glycogen determination, PAS staining and E.M. examination. High glycogen content was detected in the livers of fed rats. The livers showed discrete glycogen particles in contact with vesicles of SER in cetrilobuar hepatocytes and glycogen lacks surrounded with few vesicles in periportal areas. Liver of fasted animals showed low glycogen level and marked reduction of glycogen content with extensive SER proliferation especially in centrilobular hepatocytes. The study provides evidence of the regional variation in ultrastructure and glycogen distribution in fasted and fed animals. The study reflects more light about the dynamic action of SER in relation to both hepatocytic glycogen deposition and depletion according to the nutritional status. The variation in strength and distribution of PAS staining of hepatocytes of fed rats could be clarified in light of their ultrastrucre and lobular location. A close relationship was observed between peroxisomes and both glycogen particles and SER suggesting a role of peroxisomes in glycogen synthesis. We recommend that the study of the ultrastructure of the liver should be always correlated to the nutritional status of the animals, a precise determination of liver glycogen level for each particular spacemen and accurate localization of the hepatocytes in relation to their lobular patern

Possible reversible action of phenobarbital of the liver of the albino rat

Three groups of rats were used in this experiment, a control, a phenobarbial-treated and a reversible group. Each animal in the control group received 80 mg/kg body weight of saline intraperitonal. Each animal in the phenobarbital-treated group received 80 ml/kg body weight of phenobarbital intraperioneally for 5 days. Animals of the reversible group were left one weak after receiving the same dose of the drug as the treated group. Daily measurements of body weight were performed and liver weight was calculated in the day of sacrifice. Enzymatic liver glycogen determination. PAS staning and electron microscopic studies of liver cells were done. The results shows that phenobarbital causes reduction in the body weight with increase in the liver weight. Proliferation of smooth endoplasmic reticulum was found to be the main factor reponsible for the increase in liver weight. The drug affects all the three zone of the hepatic lobule with particular ultrastructural patter in each zone. There was an increase in lipid droplets deposition mainly in the midlobular zone. All changes in the body weight, liver weight, glycogen content and ultrastructure were reversible after one week of cessation of phenobarbital treatment

Ultrastructural changes in the hepatocytes of albino rats treated with high doses of rifampin

Twelve rats were used, of which 6 rats received 400 mg/kg rifampicin daily for 5 days through an intragastric route, 3 rats received equivalent amounts of saline daily for 5 days, and 3 rats received nothing. The animals were sacrificed on the 6th day after initiation of treatment. Hepatic tissues were taken from all animals and were processed for electron microscopic study. In EM study. there was reduction of glycogen content in all centrilobular hepatocytes, in which few discrete glycogen particles appeared in relation to SER. The periportal hepatocytes showed heterogeneous response in which some cells kept high levels of glycogen and other cells showed marked reduction in glycogen content. There was mild proliferation of SER in both periportal and centrilobular hepatocytes while RER was increased in both areas. Intimate relation between RER and mitochondia was explained