Sequence Of Morphological Changes Research Articles

Formation of electrical synapses between isolated, cultured Helisoma neurons requires mutual neurite elongation

Our previous experiments have suggested the hypothesis that conjoint active neuronal outgrowth may be necessary for formation of new electrical synapses between identified neurons of adult Helisoma buccal ganglia. This growth dependence hypothesis now has been tested by examining the responses of individual pairs of neurons in isolation from the influences of the ganglionic environment. Isolated cell culture of identified neurons (neuron 5) showed that: (i) neurons growing in cell culture undergo a predictable sequence of morphological changes culminating in a stable morphological state (i.e., growth stops); (ii) contact between actively growing neurons in cell culture results in the formation of electrical connections, just as in ganglia; and (iii) when an actively growing neuron encounters a neuron that is morphologically stable, electrical connections do not form or are very weak, even though strong connections are made between pairs of actively growing neurons in the same culture. These results establish that processes closely associated with growth are required for formation of electrical synapses between these neurons.

Is shock the mode of death in SIDS?

Sequential morphological changes as found in the organs of 179 SIDS infants are described. Detailed examination of macroscopic and microscopic heart lesions reveal extensive myocardial lesions which can be best described as selective focal anoxic muscle fibre necrosis at different developmental stages. Varying from case to case the myocardial lesions present themselves in an acute and subacute phases, and in most cases both phases are present at the same time. These lesions are shown to be identical with the myocardial lesions as encountered in shock and many other conditions observed in clinical cases and in experimental laboratory animals. Lesions in other organs are consistent with the effects due to cardiogenic shock. A conclusion is reached that cardiogenic shock leading to acute cardiac failure is the primary final cause of death in all SIDS infants.

The quantitative description of beach cycles

A quantitative method is developed to describe sequential changes in beach profile morphology. Dominant cycles in temporal eigenfunctions (computed by empirical eigenfunction analysis and rotary component analysis) are defined and used to construct a sequence of profiles representing the energetic portions of beach cycles. Five sets of beach profile data from Torrey Pines Beach in southern California were analyzed with these techniques. Because the first and second eigenfunctions account for between 65 and 90% of the variability of the data, the beach profiles are accurately described with only these two variables and the mean profile. Using rotary component analysis, beach changes represented by the two dominant eigenfunctions can be separated into many elliptical components, each representing a particular frequency associated with cycles in beach state. Profiles are reconstructed using points from the perimeter (latera recta) of these beach state ellipses. A frequency of 1 cpy is the most energetic frequency in the first and second eigenfunctions, corresponding to the cyclic onshore—offshore sediment movement associated with “bar” and “berm” profiles. Profiles constructed from points on the elliptical path associated with annual cycles graphically depict the sequential development of bar and berm during the beach cycle. Beach cycles corresponding to a frequency of 2 cpy are also significant, primarily due to the energy of the second eigenfunction. No other frequencies are consistently found to be as significant as the annual and semi-annual cycles at this beach. In particular, monthly beach cycles have little energy associated with them. The method described provides a uniform way to objectively discriminate energetic beach cycles, and yields a concise representation for beach modeling and prediction. It should be a valuable tool for uniform, quantitative intercomparison of beaches and beach cycles.

Intracellular calcium redistribution during mating in Chlamydomonas reinhardii

Gametes of the unicellular green alga Chlamydomonas reinhardii recognize and adhere to cells of the opposite mating type by flagellar contact. Adhesion between these specialized organelles signals a rapid series of mating events which result in gamete fusion. The sequence of morphological changes (flagellar tip activation, cell wall loss, and mating structure elongation), which occur as a consequence of the sexual signalling, have been characterized. The signalling mechanisms have, however, not been defined. Calcium is known to be involved during fertilization of animal species. Increased intracellular free calcium, which can be achieved either by calcium influx or by mobilization of ions from intracellular stores, has been observed during activation of both eggs and sperm. A recent report by Bloodgood & Levin that gametes of C. reinhardii preloaded with 45Ca showed a transient increase in Ca efflux following mating, suggests that intracellular Ca redistribution may also accompany mating in this algal species. We have used X-ray microanalysis to analyze the subcellular distribution of bound calcium during mating in Chlamydomonas reinhardii. X-ray maps reveal that calcium is sequestered in discrete granules within the gamete cell body prior to mating and that during activation and cell fusion, calcium is diffuse throughout the cell. This suggests the possibility that calcium serves as a second messenger in this species.

Non-Hodgkin's lymphoma classification: Ultrastructural morphometric studies for the quantification of nuclear compartments in situ

The condensed chromatin distribution in the nuclei of lymphocytes in non-Hodgkin's lymphoma (NHL) is a key element, along with nuclear size and shape, in the classification of this disease for therapeutic and prognostic purposes. This report describes the ultrastructural comparative quantification of the condensed chromatin and the interchromatinic (nuclear matrix or euchromatin) region in the nuclei of mitogen-stimulated human peripheral T lymphocytes and mouse spleen B lymphocytes, human germinal center lymphocytes, and lymphocytes in ten cases of NHL of a variety of subtypes. The sequential morphologic nuclear changes induced in lymphocytes by mitogens are reflected in human germinal center lymphocyte populations. The common features include the changes in the distribution and volume of condensed chromatin aggregates, as well as the fact that the major increments in nuclear volume during lymphocyte transformation result from increases in the volume of the interchromatinic region. In all subtypes of NHL analyzed morphometrically, subpopulations of lymphocytes were identified in which mean nuclear, condensed chromatin, and interchromatinic volumes were more or less equivalent to those of normal lymphocyte subsets in germinal centers in reactive hyperplasia. However, in NHL the abnormal cytologic characteristics of the nucleus result, at least in part, from a complex interplay of condensed chromatin distribution and amount, and the size of the interchromatinic region. Further complexity is introduced by the fact that in NHL these two nuclear compartments can independently be normal, increased, or reduced in size. Morphometric quantification of lymphocytes in NHL indicates that the interchromatinic (matrix) region of the nucleus is the key element in establishing the nuclear volume of neoplastic lymphocytes. The structural and functional, ribonucleoprotein interchromatinic region of the nucleus was visualized in normal and neoplastic lymphocytes by regressive uranyl-EDTA staining. Quantitative morphometric analysis indicates that the cytologic appearance of neoplastic lymphocytes, even within subtypes of NHL, is heterogeneous and that condensed chromatin quantity and distribution may be more critical than nuclear size in distinguishing between certain subtypes of NHL. Improvements in the classification of NHL will occur only with understanding of the alterations in the biologic mechanisms controlling gross nuclear organization and the morphologic events of the various differentiation pathways available to antigen-stimulated lymphocytes.

Direct observation of the "oxygen paradox" in single rat ventricular myocytes.

By phase contrast microscopy with video length tracking, we followed the sequence of morphological changes in individual isolated rat ventricular myocytes during anoxia followed by reoxygenation. Cells appeared normal during early anoxia. After a duration of anoxia T1, which varied from 17-47 minutes in different cells, each cell abruptly contracted an average of 33% in length to an inert rectangular form presumed to be a rigor state. Cells which were reoxygenated before the onset of rigor showed normal morphology and an unchanged extent of shortening on field stimulation, compared to control. Cells that were reoxygenated after a time in the rigor state, T2, either partially recovered to a shortened rectangular form capable of stimulated twitches or rounded up rapidly to a disordered hypercontracture form. The distribution of T1 was the same for cells which recovered and which hypercontracted. In contrast, the outcome of reoxygenation depended markedly on T2: all cells that were reoxygenated after less than 10 minutes of rigor recovered function, whereas all cells that spent more than 20 minutes in rigor hypercontracted when reoxygenated. The hypercontracture appears to be the cellular analog of the "oxygen paradox" in whole hearts. Its occurrence is reliably related to duration of rigor state but not to duration of hypoxia, because of marked cellular variability in the time of onset of rigor.

Polychlorinated biphenyl induction of hepatocellular carcinoma in the Sprague-Dawley rat.

Male and female Sprague-Dawley rats (70 males and 70 females in the initial group) were fed a diet containing a polychlorinated biphenyl mixture (Aroclor 1260, 100 ppm for 16 months and 50 ppm for an additional 8 months) for 2 years followed by a control diet for 5 months. A control group initially consisted of 63 males and 63 females. Sequential morphologic changes were evaluated throughout the study. In the PCB-exposed group the following hepatocellular lesions developed in sequence: centrolobular cell hypertrophy at 1 month, foci of cell alteration at 3 months, areas at 6 months, neoplastic nodules at 12 months, trabecular carcinoma at 15 months, and adenocarcinoma at 24 months. In addition, simple and cystic cholangioma at 18 and 23 months, respectively, and adenofibrosis at 22 months were present. With the exception of hepatocyte hypertrophy and adenofibrosis, all lesions contained cells that were positive for gamma glutamyl transpeptidase activity. In the PCB-exposed group that was examined after 18 months, hepatocellular neoplasms were present in 95% of the 47 females and in 15% of the 46 males. Distant organ metastases did not occur and the mortality rate was not increased in the PCB exposed group. In 81 control rats examined after the 18th month, only 1 hepatocellular neoplasm (a neoplastic nodule) occurred. PCB- exposed and control rats developed simple cholangioma, cystic cholangioma and adenofibrosis; the incidence of each was greater in the PCB group. Thus, within the Sprague-Dawley rat group exposed to a diet with relatively high concentrations of Aroclor 1260 for 2 years a hepatocarcinogenic effect manifested by formation of slowly growing hepatocellular carcinomas was produced.

An electron microscopic demonstration of induction of chondrogenesis in neonatal rat muscle outgrowth cells in monolayer cultures.

Second passage fibroblast-like cells grown from explants of neonatal rat muscle continue to demonstrate fibroblast-like properties for many days when cultured on plastic surfaces. Such cells can be induced to change to a chondrocyte-like mode of expression by the addition of effector materials prepared from bovine cortical bone decalcified with 0.6 N HCl. Other studies show that similar demineralized bone particles and extracts from them have, in vivo, osteoinductive properties. Optimum conditions for this differentiation in monolayer culture were found in the use of 2% fetal calf serum with Dulbecco's modified Eagles medium. At 10% fetal calf serum the chondrogenic changes could not be detected. Light microscopy showed a sequence of morphological changes, after 36 h in culture, which resembled those seen at the beginning of osteogenesis in vivo. Induced cultures showed abundant extracellular proteoglycan production. Isotope incorporation studies showed stimulation of glycosaminoglycan synthesis in response to effector materials in soluble form. Type II collagen could be detected after three days. Electron microscopic analysis of induced and control cultures showed unequivocal evidence for marked production of an extensive extracellular matrix in the region of effector particles. The cells themselves change shape and develop an abundant system of lysosome-like vesicles and a very active, highly engorged endoplasmic reticulum and Golgi apparatus. After nine days in culture, evidence for the formation of a ruthenium red stained structure on the surface of the cells in contact with inductive particles, was observed. The simple monolayer culture system described provides a direct means by which the presence of active chondrogenic fractions may be assessed, and in which the mechanism of action of the effectors can be studied.

Analysis of peritoneal macrophages in continuous ambulatory peritoneal dialysis patients

Peritoneal macrophages (PMC) from patients undergoing continuous ambulatory peritoneal dialysis (CAPD) were compared to peritoneal macrophages from healthy volunteers and to peripheral blood monocytes (PBM) from CAPD patients, hemodialysis patients, and healthy volunteers. PMC from CAPD patients had morphology similar to PMC and PBM from healthy volunteers. HLA-DR antigen and Fc receptors were present on the cell surface. These monocytes had similar sequential morphologic changes in long-term culture compared to PBM from healthy volunteers. Phagocytosis, hydrogen peroxide generation and bactericidal activity were the same in PMC from CAPD patients as in PBM from healthy volunteers. Chemotaxis and eicosanoid precursor uptake studies suggest that PMC from CAPD patients may be relatively immature bone-marrow-derived cells. Although these cells function well as phagocytes, further study is warranted to define their immune competence, many components of which develop during differentiation into mature macrophages and may therefore be deficient in patients undergoing CAPD.

Sequential morphological and functional changes in kaolin-induced hydrocephalus.

An experimental model of kaolin-induced hydrocephalus in the dog was studied in order to evaluate the progress of ventricular dilatation and the communications between the ventricular system and the subarachnoid space. Skull and spine radiological studies were obtained after metrizamide intraventricular injection, and the baseline ventricular pressure and cerebral pulse pressure amplitude were measured in anesthetized animals. Intracranial compliance and resistance to drainage of cerebrospinal fluid were calculated by means of bolus injection test. Light and scanning electron microscope studies were done at different developmental stages of hydrocephalus. With these experimental parameters, two successive phases were seen: an initial acute hypertensive hydrocephalus (H1) with high resistance, low compliance, severe ependymal damage, and subependymal edema; and a late chronic normotensive hydrocephalus (H2) with little resistance increase, normal compliance, epithelial regeneration, and subependymal gliosis. Both the H1 and H2 stages showed an increase in the cerebral pulse pressure amplitude.

Sequential analyses of the development of lymphoproliferative disorders in rats receiving cyclosporine.

Cyclosporine (Cys)-associated, atypical lymphoproliferation in gut-associated lymphoid tissue (GALT) was reproducibly observed in male Sprague Dawley rats by feeding a diet containing 0.015% Cys. Sequential morphological changes occurring in the lymphoid organs of the rats on a Cys diet for 8-10 weeks were examined, and these changes were correlated with those observed in electrophoretic patterns of serum proteins. Proliferative lymphoid alterations were detected in the GALT after 2 weeks of feeding, and these progressed through 8 weeks. Atypical lymphoid proliferation was also seen in lymph nodes after 8 weeks of feeding; thymuses showed marked medullary atrophy, and spleens had a diminution of their periarterial lymphoid sheaths. Elevated levels of gamma-globulin were detected after 4 weeks of Cys administration, and became more pronounced by 8 weeks. The lymphoid lesions induced in rats bear striking similarities to the post transplant lymphoproliferative lesions in patients receiving Cys and in patients with the acquired immune deficiency syndrome.

Histopathological changes in the brain of mice given Clostridium perfringens type D epsilon toxin

The distribution, severity and frequency of brain lesions produced in mice by the administration of Clostridium perfringens Type D epsilon toxin were examined by light microscopy. The granular layer of the cerebellum was the area most frequently affected in mice given single doses of toxin. Sequential changes in brain morphology were examined from 1 h to 7 days after injection of toxin. Lesions progressed from an initial vasogenic oedema to malacic foci which commonly were focal and bilaterally symmetrical, with a predilection for white matter. The topographical distribution of these malacic areas is discussed.

From bone lining cell to osteocyte--an SEM study.

We describe the SEM appearance of the rat endosteal bone lining cell ( BLC ) population, and the sequence of morphological changes of these cells as they self-incorporate into unmineralized bone matrix (osteoid), establish intercellular connections, and construct lacunae. The osteoblast/nascent osteocyte series was progressively unsheathed by gentle digestion of the osteoid with 0.25% collagenase. The osteoblasts which leave the polygonally packed BLC compartment rapidly develop numerous complexly branched processes that contact the processes elaborated by previous generations of maturing and mature osteocytes. As osteoblasts mature and approach the mineralization front, they appear to lose processes. The mature cells begin to form osteocyte lacunae by depositing an asymmetric perimeter of woven collagen fibrils, such that as the cells roof-over, the lacunae appear as pocketlike constructions. The collagen fibrils on the perilacunar matrix are oriented in a tangential or circular pattern, while those in the more distal matrix are arranged in a parallel pattern. With the completion of a lacuna, its wall appears to mineralize quickly, for lacunae could be recognized only when they are forming.

Sequential morphologic changes in adult Echinococcus granulosus during complement-mediated lysis In vitro

Herd R. P., Ko L., Weisbrode S. E. and Heath D. D. 1984. Sequential morphologic changes in adult Echinococcus granulosus during complement-mediated lysis in vitro. International Journal for Parasltology 14:141–149. Sequential changes (5,10, 20, 30,40, 50 min, 1, 2, 3, 4, 5, 6, 7, 8, h) were observed by light, scanning and transmission electron microscopy after 38-day-old adult Echinococcus granulosus were exposed to 50% guinea pig serum in vitro. Early changes within 3 h included contraction of worms, fusion of microtriehes, vacuolization and vesiculization of the distal cytoplasm, followed by rupture of vesicles leading to erosion and loss of the distal cytoplasm. This was most marked in the terminal proglottid but ultimately there was complete erosion of the distal cytoplasm of all proglottids and the scolex. After 3 h there was loss of definition of organelles, apparent edema of the perinuclear cytoplasm and, in some instances, rupture of the circular muscle layer with extrusion of parenchyma. Adult tape-worms exposed to heat-inactivated complement showed none of these changes. Lysis and death of the parasite was attributed to osmotic changes subsequent to the formation of trans-membrane channels induced by complement-mediated attack of the tegument after activation of the alternate pathway by factors present in the cestode tegument.

Hyaline articular cartilage dissected by papain: light and scanning electron microscopy and micromechanical studies.

Papain was used to digest the hyaline femoral condylar cartilages of 30 adult Wistar rats. Matrix proteoglycan degradation was assessed by the light microscopy of paraffin sections stained with toluidine blue. The extent of surface structural change was estimated by scanning electron microscopy, and the structural integrity of the hyaline cartilage tested by the controlled impact of a sharp pin. The results demonstrated an early loss of cartilage metachromasia, increasing with time of papain digestion, and an alteration in the shape of the cartilage splits produced mechanically. Accompanying the loss of matrix material was a conspicuous sequence of morphological changes in cartilage surface structure. The results confirm a close relationship between matrix integrity, mechanical properties, and fine structure.

Liver injuries induced by cyclochlorotine isolated from Penicillium islandicum.

Sequential morphological changes in murine liver induced by cyclochlorotine (CC), a secondary metabolite of Penicillium islandicum were investigated by transmission electron microscopy and scanning electron microscopy. Within 15 min after the administration of CC there was a marked dilatation of Disse's space around the portal triads, and the exudates then poured out into the space which was formed by the invagination of the hepatocyte plasma membrane. Shortly after the invagination was completed, the connection between Disse's space and the invaginated space was pinched off, so that this space became a membrane-bound vacuole. After dehydration, the vacuoles became granular. The liver injuries induced by CC were influenced by various pretreatments. The results indicate that drug-metabolizing systems mediated by cytochrome p-450 in the hepatocytes may play an important role in the hepatotoxicity of CC.

Pathology Produced by Sulfur Mustard in Human Skin Grafts on Athymic Nude Mice. II. Ultrastructural Changes

AbstractThe human skin graft/nude mouse model was used to study sulfur mustard (SM) -induced pathology of skin at the ultrastructural level. The electron microscope confirms and extends the histopathology previously noted under light microscopy. SM caused extensive injury to the basal keratinocytes, the severity of which was dependent on both time and dose. Ultrastructurally visible damage took several hours to develop. The following sequence of morphological changes was observed: (a) Extensive condensation and margination of heterochromatin and loss of euchromatin, (b) blebbing of the nuclear membrane, (c) appearance of perinuclear vacuoles, (d) swelling of the endoplasmic reticulum, (e) progressive dissociation of rosettes of free polyribosomes, (f) formation of cytoplasmic vacuoles, (g) loss of the integrity of the basal cell plasma membrane, (h) leakage of cell contents and debris into the lamina lucida, (i) disruption of the anchoring filaments of hemidesmosomes with separation of the plasma membrane...

Sequential morphological changes in the dog brain after interstitial iodine- 125 irradiation

Sequential morphological changes in the dog brain after interstitial iodine- 125 irradiation

Chlordecone-induced potentiation of carbon tetrachloride hepatotoxicity: A light and electron microscopic study

Previous studies have shown that a chlorinated pesticide, chlordecone (Kepone), greatly potentiates carbon tetrachloride (CCl 4) hepatotoxicity and lethality (Curtis, L. R., Williams, W. L., and Mehendale, H. M. (1979). Toxicol. Appl. Pharmacol. 51, 283–293; Curtis, L. R., and Mehendale, H. M. (1980). Drug Metab. Dispos. 8, 23–27). The present study describes sequential morphologic changes which occurred in livers of rats given a “nontoxic” level of chlordecone (10 ppm for 15 days) followed by a single injection of CCl 4 (0.1 ml/kg). The hepatic alterations were examined 1 to 36 hr after exposure of the rats to CCl 4. Those changes were compared to hepatic alterations which occurred in rats that received the same dose of chlordecone (10 ppm for 15 days) or a single injection of CCl 4 (0.1 ml/kg) alone. The only change noted in livers from rats that received chlordecone alone was focal increase in smooth endoplasmic reticulum (SER) of hepatocytes at 24 hr and continuing throughout the time course of the experiment. Livers from animals that received CCl 4 alone showed morphologic changes at 6 hr consisting of glycogen loss, increase in SER, and dilatation of rough endoplasmic reticulum (RER) in pericentral hepatocytes. Accumulation of small lipid droplets was also noted in midzonal hepatocytes. After 6 hr, there was no further increase in severity of injury. At 12 hr recovery was noticeable and, by 36 hr, livers from the CCl 4 group appeared normal. Prior administration of chlordecone greatly potentiated pathologic changes in livers of animals that received CCl 4. By 4 hr, there was total loss of glycogen in hepatocytes throughout the entire lobule. Small lipid droplets were present in pericentral, midzonal and periportal hepatocytes. Hepatocytes with extremely dilated RER were randomly scattered throughout the entire lobule. At 6 hr, there was further accumulation of lipid in the form of large droplets in hepatocytes. Focal, necrotic cells surrounded by polymorphonuclear leukocytes were randomly distributed throughout the lobule. The number of necrotic foci had progressively increased at the 12- and 24-hr intervals. By 36 hr, confluent areas of necrosis in pericentral and midzonal areas were observed in livers of some animals. This study indicates that although the combination of chlordecone and CCl 4 produces much greater hepatic injury resembling damage due to a massive dose of CCl 4, histologically, some differences in the progression and distribution of hepatocellular damage within the lobular architecture of the liver are evident.

Infantile Acropustulosis and Granuloma Gluteale Infantum

INFANTILE ACROPUSTULOSIS In 1979, two reports, published simultaneously in the Archives of Dermatology, described a new cutaneous disorder, infantile acropustulosis.1,2 The authors of these papers indicated that patients with this eruption had been discussed at national dermatology meetings as early as 1976, although no studies had previously been documented in the literature. Both the presentations at meetings and the written descriptions evoked instant recognition of this entity by pediatric dermatologists, many of whom recalled the frustration of caring for such an infant whose eruption defied diagnosis and effective management. Clinical Findings Infantile acropustulosis is truly a disorder of infancy with onset usually between 2 and 10 months of age. However, both Kahn and Rywlin1 and Lucky and McGuire3 described infants purported to have lesions at birth. Despite the paucity of reported cases of infantile acropustulosis, the collected experience has suggested that black males have a predisposition for this eruption, although affected infants of both sexes and all races have been identified. The lesions of this disorder are quite characteristic, demonstrating a rapid sequence of morphologic changes as they evolve. Early lesions are discrete, 1- to 2-mm erythematous papules, which became vesiculopustular within 24 hours (Fig 1, top left) and subsequently crust prior to healing.