Vol. 25 - Issue 3 - 2001
STRUCTURE
AND ULTRASTRUCTURE OF THE SECRETORY GLANDS
IN
THE GENUS, Polygonum (L.), SECTION PERSICARIA (POLYGONACEAE)
S.J. Gattuso
ABSTRACT:
The aim of this
paper is to present the structure of exocrine glands in P. glabrum, P. amphybium,
P. minus, P. persicaria and P. punctatum, of them from section Persicaria,
family Polygonaceae.
The observations were performed with light, scanning and transmission electron
microscope, using routine techniques for sample preparation.
The structures observed at superficial view are composed of four cells flanking
a small pore in the middle, and surrounded by a number of rather small cells,
followed by normal epidermic cells. In the cross section the structure is
composed of a great cavity filled with secretion, and communicated with the
external side of the pore. The cavity is internally surrounded by a flat cell
epithelium separated from the mesophyll by a layer of parenchymatic cells.
CONFOCAL LASER SCANNING,
CONVENTIONAL SCANNING AND TRANSMISSION
ELECTRON MICROSCOPY
OF VERTEBRATE CEREBELLAR GRANULE CELLS
O.J. Castejón,
H.V. Castejón, R.P. Apkarian
ABSTRACT: Confocal laser scanning microscopy of hamster cerebellar granular layer showed in montages of z-series the presence of small, medium and large granule cells. A granule cell Golgi cell ratio of 50/4 was observed surrounding glomerular regions. Field emission high resolution scanning electron microscopy of mouse cerebellar granular and molecular layers showed SE-I images of the outer and inner surfaces of nuclear and cytoplasmic compartments of chromium coated granule cells and the axo-spinodendritic synapses of parallel fibers with Purkinje cell dendrites. Conventional scanning electron microscopy of teleost fish cerebellar cortex showed three dimensional morphology of granule cell soma and processes and the synaptic relationship with mossy and climbing fibers, Golgi cell axonal ramifications and dendrites of stellate neurons, by means of SE-II and SE-III signal image mode, in sagitally and transversally cryofractured cerebellar cortex. SE-II images of the non-synaptic segments and synaptic varicosities of parallel fiber outer surface were characterized in the molecular layer. Ultrathin sections of transmission electron microscopy (TEM) revealed somato-somatic, dendro-somatic and dendro-dendritic like-desmosomal and like-hemidesmosomal junctions in human cerebellar granule cells. Freeze-etching replicas of mouse cerebellar cortex displayed granule cell intramembrane morphology, cytoplasmic fractured face and the Bergman glial cell cytoplasm completely surrounding the parallel fibers in the molecular layer. The mossy fiber-granule cell dendrite synaptic relationship was observed in sagitally and transversally cryofractured cerebellar cortex and correlated with TEM images. SE-II images of the climbing fiber synaptic connections with granule cell dendrites were obtained in teleost fish cerebellar cortex. One to one axo-dendritic synaptic contacts between Golgi cell axonal ramifications and granule cell dendrites were also seen. The above findings provide new vistas for future studies dealing with intracortical circuits and information processing in the cerebellar cortex.
MUSCULAR
REGENERATION AFTER MYONECROSIS INDUCED BY
Bothrops jararacussu SNAKE VENOM FROM ARGENTINA
P. Teibler, O. Acosta de Pérez, S. Maruñak, M. Sanchez Negrette,
H. Ortega
ABSTRACT: Venom
from Bothrops snake produces severe local symptoms on the envenomed victim,
such as hemorrhage, edema and myonecrosis. The latter is perhaps the most
important of all, since antivenom therapy is not effective for it, even
when antivenom is injected only a few minutes after the accident. In this
work, mice weighing 18-20 g (n=5) were inoculated with 70 µg Bothrops
jararacussu venom in 0.1 ml PBS in the gastrocnemius muscle. Mice were sacrificed
using ether after 1, 12 hours, 3, 5, 7 days and 2, 3, 5, 6 weeks after the
injection of the venom to obtain gastrocnemius muscles. They were fixed
with Bouin's solution and stained using Hematoxylin - Eosin and Mason's
trichromic stain was applied to visualize collagen fibers.
Results showed that inflammatory reaction was evident after a few minutes
of the venom injection, which was not evident after 6 weeks. Muscular fiber
necrosis reached its highest level on the seventh day. Even thought regeneration
of muscular fibers was important, they never reached the size of the control.
We conclude that Bothrops jararacussu venom causes severe necrosis on muscle
fibers with partial recovery, showing low hemorrhage and abundance of granulation
tissue. This points that not all fibers were regenerated, which can be seen
as a functional sequel for injuried muscle.
ADHESION
OF Lactobacillus VAGINAL STRAINS WITH PROBIOTIC
PROPERTIES TO VAGINAL EPITHELIAL CELLS
V. Ocaña, M.E. Nader-Macías
ABSTRACT: The capability of lactobacilli to adhere to vaginal epithelial cells (VEC) has been found to be an important factor in the formation of a barrier to prevent colonization of pathogenic bacteria. The aim of this study was to examine the adhesion ability to VEC, of vaginal Lactobacillus which had been selected for their probiotic properties. A modification of the Mardh and Weströn method was employed for this purpose. Adherent bacteria were determined as CFU-grown using selective media. There was a slight degree of difference in the adhesion properties observed among vaginal and non-vaginal Lactobacillus. Different pH values of 4 and 7 did not affect adhesion (P<0.70). Scanning and transmission electronic microscopy were performed to illustrate the adhesion of the self-aggregating L. salivarius CRL 1328.
CHANGES
IN THE HEPATOPANCREAS HISTOLOGY OF
Palaemonetes argentinus (CRUSTACEA, CARIDEA) DURING MOUL
L.G. Sousa, A.M. Petriella
ABSTRACT: The present work describes the histological changes in the hepatopancreas of Palaemonetes argentinus during the moulting cycle. The hepatopancreas of individuals at different moult stages were dissected and studied using histological techniques. The hepatopancreas in intermoult presents four typical cell types (E, F, R and B) and follows the general plan of the rest of decapods. During early premoult (D1), there is an important secretory activity and many R-cells have several subapical vacuoles and are highly columnar. In early postmoult (A), B-cells are confined to the proximal zone of the tubules. Some of the tubules show a folded basal lamina in late premoult and postmoult. Degenerative desquamation occurs at the proximal zone of the tubules in all the stages, this zone being replenished by mitosis of E cells. Mucopolysaccharides and glycogen reserves are more abundant in premoult than in the rest of the cycle. Cellular height increased in premoult and decreased towards the intermoult, stage of more stability. R-cells are the most abundant, and F-cells do not change significantly through the cycle. The observations suggest that the hepatopancreas of P. argentinus undergoes a significant dynamic and cellular turn over rate in relation to moult.
CONCENTRATION-DEPENDENCE
OF DITHIOTHREITOL
EFFECTS
ON RAT DISTAL COLON ELECTROPHYSIOLOGY
F.D. Saraví, T.A. Saldeña, O.R. Arrieta, L.M. Cincunegui, G.E.
Carra
ABSTRACT: Dithiothreitol (DTT), at 1 mmol/L or higher, is widely used as a mucolytic in gastrointestinal research. Previous observations suggest that it may be toxic to the mucosa. DTT effects on the mucosal electrical behavior were assessed. Cumulative concentration-response relationships of DTT effects on rat distal colon mucosa were studied. Isolated mucosa preparations were mounted in an Ussing chamber under short-circuit conditions. The effects of concentrations ranging from 1 µmol/L to 1 mmol/L, applied to either the mucosal or serosal side, were studied. As compared with control, untreated preparations, DTT depressed short-circuit current at 10 µmol/L and higher when applied to the serosal side, and at 50 µmol/L and higher when applied to the mucosal side of the epithelium. On the other hand, transepithelial resistivity showed a progressive increase with DTT applied to either side at a concentration of up to 500 µmol/L, while at the highest concentration (1 mmol/L) a marked decrease in resistivity occurred. Neither the short-circuit current decrease, nor the resistivity collapse showed recovery after repeated rinsing with DTT-free solution. It is concluded that DTT affects epithelial electrical properties at low concentrations, and therefore its use as a mucolytic for electrophysiological studies should be discouraged.
LEAD
IONS BUT NOT OTHER METALLIC IONS INCREASE RESISTENCE TO
HYPOTONIC LYSIS IN PRENATAL HEMOPOIESIS RED BLOOD CELLS
J. Corchs, I.A. Gioia, R.E. Serrani, D. Taborda
ABSTRACT:
Metals known to have toxic effects on exposed individuals (Aluminum (Al),
Cadmium (Cd), Zinc (Zn) and lead (Pb)) were selected.
Umbilical cord erythrocytes from normal newborns were incubated in isotonic
media alone or with addition of Pb (20 µM), Cd, Zn or Al (concentration
range: 20-250 µM). Red cells were then placed in media of diminishing
tonicity, to measure cellular lysis and volume; the regression curves of percent
lysis as a function of osmolarity were determined for each data set and the
break points calculated. Resistance to lysis increased significantly in Pb
treated cells whereas cells treated with the other metals did not differ from
controls, even at concentrations ten times higher than that of Pb. Lead produced
a reduction in cellular volume corrected by addition of quinidine (an inhibitor
of potassium channels activation) to the cell suspension; on the other hand,
quinidine did not modify the effect of lead on lysis sensitivity. These results
suggest that the effect of lead on cell resistance to lysis might be mediated
by changes in membrane structure. The other metals examined did not affect
the variables studied.