Bradypus Tridactylus Research Articles

Correlative scanning and transmission electron microscopic study on the ependymal surface of Bradypus tridactylus.

Topographical variations of the ependymal surface of the whole brain ventricular system of Bradypus tridactylus were studied at the scanning electron microscope after CO2 critical point drying and carbon-gold coating. Certain selected areas were also studied at the transmission electron microscope, following standard technical procedures. We observed distinct patterns in the distribution of cilia, microvilli and supraependymal structures (nerve-like and fibrous astrocyte fibers), and also a small number of blebs. It the lateral transition zone between the floor and roof of the lateral ventricle were found interconnected stellate bulgings measuring an average 98 x 190 microns, constituted by a complex meshwork of processes from fibrous astrocytes, without ependymal lining and with few cell bodies. In the junction between these formations and the underlying neuropil, ciliated ependymal-cell-like glial cells were found to delimit complex labyrinthic spaces. Based on the morphological findings, morpho-functional considerations are made.

Sleep and waking in the three-toed sloth, Bradypus tridactylus

1. 1. The sleep-waking cycles of the three-toed sloth, Bradypus tridactylus, were studied by direct observation and polygraphic recording and the results were correlated. 2. 2. Three states of waking behavior were recognized, “awake-exploring”, “awake-alert” and “awake-fixating”. 3. 3. EEG recordings were classified as two waking states. A 1 which was seen during both “awake-exploring” and “awake-alert” behavior and A 2, which had some of the characteristics of drowsy behavior of other mammals and often accompanied the “awake-fixating” behvaior. 4. 4. EEG patterns of sleep were divided into five types: two in light sleep, two in deep sleep and one in paradoxical sleep. 5. 5. Animals spent about 30% of the time in various degrees of waking behavior and about 70% asleep. 6. 6. Waking EEGs of various types were seen about 34% of the time, about 10% of that during behavioral sleep. 7. 7. EEG patterns of light sleep constituted about 56% of the records, about 6% of that during some form of waking behavior. 8. 8. EEG patterns of deep sleep constituted about 10% of the records; all of this came during behavioral sleep. 9. 9. The total duration of sleep and of paradoxical sleep did not depart materially from the expected pattern based on phylogenetic position. 10. 10. The pattern of sleep is polycyclic but in the laboratory situation animals were sleeping most soundly between 6 a.m. and noon.

Isolation and convulsivant effect of the “insulin-like” protein obtained from the exocrine pancreas of Bradypus tridactylus L.

1. 1. A pancreatic insulin-like protein fraction with low electrophoretic mobility showing high molecular weight is present. 2. 2. Isoelectric focussing studies showed that the high molecular weight protein has a pI about 7.4 when used at a pH range between 3.5 and 8.0. 3. 3. The partially purified aldehyde-fuchsin positive high molecular weight protein fraction gave a positive effect for the convulsivant test in mice. 4. 4. A high molecular weight insulin-like protein in pancreatic juice was found. 5. 5. Insulin was found by radioimmunoassay in the basal and post stimulation pancreatic juice.

The effects of posture on blood pressure and heart rate in the three-toed sloth, Bradypus tridactylus

1. 1. In unanesthetized, minimally restrained three-toed sloths, Bradypus tridactylus, the mean arterial pressure was 125 85 mmHg and the heart rate was 83.6 beats/min. There was no significant difference between these parameters whether the animal was erect or supine in the experimental chair. 2. 2. Animals without any restraint had a mean blood pressure of 133 87 mmHg and a heart rate of 78.1 beats min. There was no significant difference between these parameters whether the animal was seated or suspended from a horizontal bar and there was no significant difference between the minimally restrained and the unrestrained animals. 3. 3. Tilting from the erect to the supine position produced large increases in blood pressure parameters, 37% in systolic and 21% in diastolic, reaching the maximum effect in a mean time of 38 sec. Tilting from the supine to the erect position caused even greater increases in pressure. 43% and 38% respectively, and reaching the maximum also in a mean time of 38 sec. 4. 4. Tilting initially increased the heart rate, in going from erect to supine by 21% in 16 sec and from supine to erect by 23% in 20 sec. 5. 5. In going from erect to supine there was a reflex bradycardia later, 15% below control level with a maximum at 40 sec, and to a lesser degree in going from supine to erect, 9% with maximum at 50 sec.

The fine structure of the placental labyrinth in the sloth, Bradypus tridactylus.

The placental labyrinth of the three-toed sloth (Bradypus tridactylus) was examined by electron microscopy. The material available was from two fetuses of 55 mm and 150 mm crown-rump length (CRL). The placenta of the younger specimen was a transition form between the syndesmochorial type and the endotheliochorial type. The interhemal membrane of the 55 mm CRL specimen consisted of the following components: 1) hypertrophied maternal endothelial cells surrounding the maternal vessels; 2) a small amount of extracellular material and spindle-shaped cells, both presumed to be of maternal origin; 3) a layer of syncytial trophoblast that had an unusual, reticulated or sponge-like appearance; and 4) the fetal capillary endothelium. In addition, the fetal connective tissue contained hypertrophied mesenchymal cells that were characterized by abundant granular endoplasmic reticulum. The placenta of the 150 mm CRL fetus was poorly preserved, but it was possible to determine that the placenta was of the endotheliochorial type. There was a close apposition of maternal endothelium and trophoblast. The results confirmed virtually all of lhe light microscopic observations of Wislocki (1927; 1928b). The ultrastructure of the sloth interhemal membrane is compared to that of other endotheliochorial placentas, particularly that of the shrew, with which it shows many cytological similarities.

Some histological and histochemical studies of the pancreas of the Brasilian sloth, Bradypus tridactylus.

The histological and histochemical study of the pancreas of the three-toed sloth, Bradypus tridactylus, demonstrated that with the methods employed the pancreatic islets are apparently formed by A cells exclusively. Two different types of argyrophilic cells were noticed in the exocrine secretory units when Grimelius' method was used. The methods for the demonstration of D cells showed negative results. Aldehyde fuchsin-positive granules were only noticed at the apex of the exocrine pancreatic cells. These results are discussed in relation to current hypotheses concerning the evolution of insulin secretion mechanisms.

Ultrastructure of the Pancreas of <i>Bradypus tridactylus</i>

The fine structure of the pancreas of the South American three toed sloth, Bradypus tridactylus, is described. In exocrine cells two types of granules are found. The first variety of granules is circular, of about 0.9 micrometer mean diameter, and probably represents zymogen granules. The second type of granule is larger (up to 1.4 micrometer in diameter) and contains a granular electron-dense material which is separated from the limiting membrane by a wide space. Only one type of islet cell was found. It contains spherical membrane-bound granules of uniform size.

Dirofilaria macrodemos and D. panamensis spp. n. (Nematoda: Filarioidea) from Central and South American Sloths

Two new species of Diorfilaria, Dirofilaria macrodemos and Dirofilaria panamensis, are described from the subserosa of Central and South American sloths. Dirofilaria macrodemos, described from the three-toed sloth, Bradypus tridactylus, in Guyana, is characterized and differentiated from other dirofilarias by its length (female 214mm, male 64mm), relatively long tail (female 140 micron, male 110 micron), and the number and distribution of the caudal papillae (7 pairs) in the male. Dirofilaria panamensis, parasite of the two-toed sloth, Cholopeus hoffmanni, in Panama, was previously described as Dirofilaria incrassata by Caballero (1947), but can be distinguished from both D. macrodemos and D. incrassata on the basis of body size (female 66 mm long by 360 micron wide, male 34 mm long by 250 micron wide), tail length (female 80 micron, male 80 micron), and number (6 pairs) of caudal papillae in the male.

Characterization of the blood volume and iron kinetics in the three-toed sloth, Bradypus tridactylus

1. 1. Blood volume and iron kinetics were determined in three specimens of Bradypus tridactylus which were obtained in the coastal north-east regions of Brazil. 2. 2. The average blood volume, circulating red cell volume and plasma volume were 54.9, 19.5 and 35.4 ml/kg body weight, respectively. 3. 3. The average plasma iron disappearance half-time was 150.6min; the red cell radioiron uptake was 62% and the serum iron was 74.3 μg/100 ml. 4. 4. From these figures the plasma iron turnover rate was calculated to be 165.6 μg/kg per day and the red cell iron turnover rate 102.7 μg/kg per day.

Ultrastructural study on topographical variations of the ependyma in Bradypus tridactylus.

An electron-microscopic study of ependymal cells in 24 different areas of the encephalic ventricular system of Bradypus tridactylus was made, with a view to making a comparative analysis, of a topographical kind, of various cell components: cilia, microvilli, plasma membrane, cytoplasmic protrusions, types of cellular junctions, ribosomes, Golgi apparatus, endoplasmic reticulum, microfilaments, microtubules, mitochondria, granules and dense bodies. There were differences in the distribution of all these cytologic elements, according to the topography, being a complement to a similar work done by the same authors with light-microscopy. By means of a morphofunctional analysis they draw the conclusion that even if one can admit the passage of substances by an intracellular route, on the other hand few facts support the idea the intracellular absorption or secretion could be considered as important phenomena in a great number of the ependymal areas studied.

Mechanical properties of diaphragm of three-toed sloth

1. 1. The ultrastructure of the diaphragm of the South American sloth Bradypus tridactylus, which has hitherto not been studied, strongly resembled that of frog sartorius with reference to details of sarcomeric pattern and components. 2. 2. The same orderly array of actin and myosin filaments. M-line; M-line filaments, H-zones, and Z bands were noted. 3. 3. Mechanically, Hill's force-velocity ( F− V) equation fitted the force-velocity curve of this muscle very well. 4. 4. The muscle is faster than mammalian smooth muscle but slower than frog sartorius or diaphragm from the other sloth specie, Choloepus hoffmani. 5. 5. The increased curvature of the F− V curve and reduced value of a/ P o (0.113 vs 0.25 seen in the majority of mammalian striated muscles) indicate that the Bradypus muscle is more efficient than the others.

Sensory and motor representation in the cerebral cortex of the three-toed sloth ( Bradypus tridactylus)

Cortical sensory receiving areas were studied in 32 specimens of the three-toed sloth, Bradypus tridactylus, using the evoked response technique and barbiturate anaesthesia. Somatotopic organization in the somesthetic first area (S-I) was shown to be similar to that reported in higher mammals. The area devoted to the representation of the forelimb was considerably larger than that for the remaining body parts. The second somatosensory area (S-II), showing bilateral representation without a precise topographical organization, was identified in the rostral portion of the ectosylvian gyrus. Visual and auditory projections, occupying restricted areas, were found along the caudal banks of the ectosylvian fissure. Electrically excitable cortical motor area was explored in 8 animals anesthetized with diallyl barbituric acid in urethane. The motor representation of the various body parts was shown to coincide with the sensory projections, demonstrating the existence in a Eutherian mammal of a sensorimotor amalgam, identical to that described in marsupials. These findings suggest that sloths display a primitive pattern of neural organization, and that the sensory motor amalgam is a generalized form of cortical organization of primitive Therian mammals.

Pneumocystis and histoplasma infections in wild animals from the Amazon region of Brazil

Routine examination of tissues from wild forest rodents from Amapá, north Brazil, revealed Pneumocystis carinii in lung smears from a newly captured Oryzomys capito (Cricetidae). Acute, fatal infections with this parasite are also recorded in a number of captive “coatimundis”, Nasua narica (Carnivora: Procyonidae) and a sloth, Bradypus tridactylus (Edentata). Pneumocystis was also encountered in lung smears from a newly captured and apparently healthy sloth, Choloepus didactylus. The presence of infection in newly captured animals leads us to believe that the fatal, fulminating pneumocystosis seen in the captive Nasua and Bradypus was due to exacerbation of pre-existant infections acquired in their natural forest environment. Pneumocystis carinii is a well known cause of fatal, interstitial plasma-cell pneumonia in human infants and sometimes the weakened adult: the keeping of exotic pets such as the coatimundi is, therefore, not without some hazard in this respect. Histoplasma, another well known pathogen for man, was isolated from 4 rodents, Proechimys guyanensis (Echimyidae), all from virgin forest along the newly opened Trans Amazon Highway, Pará State, and from a single sloth, Choloepus didactylus, from near Belém, Pará. All these animals showed no symptoms of infection: isolation of the parasite was made by the inoculation of laboratory hamsters with saline suspensions of triturated liver and spleen.

Histological and histochemical study on the ependyma of Bradypus tridactylus.

Histological and histochemical aspects of the whole encephalic ventricular system of eight specimens of Bradypus tridactylus were studied. After anesthesia and perfusion, the encephalons were obtained by craniotomy. Transverse serial sections of the encephalon, stained according to Azan (Heidenhain's method) or Kluver-Barrera for nerve cells and myelinated nerve fibers; silver impregnation was carried out according to Cajal-De Castro's or Palmgren's methods. The following histochemical reactions were used: PAS (McManus), metachromasia, acid phosphatase (Gomori), Brachet's and Gomori's trichromic reaction (modified by Bargmann for neurosecretion). Histologically, different characteristics of the ependymal cells in different areas were observed, which would be related to functional peculiarities of each area of the encephalic ventricles. The ependymal cells showed discrete apical basophilia due to the presence of RNA which disappears after treatment with crystalline ribonuclease. The PAS reaction indicated the presence of a small quantity of PAS-positive substances in the apical zone of the ependymal cells and the subependymal tissue. These substances disappeared after the salivary amylase test, indicating the presence of glycogen. The acid phosphatase reaction was negative.

Neuromuscular responses of sloths.

AbstractBecause sloths are among the slowest moving of mammals, it is of interest to determine whether the rate limiting factor is in their motivation, central nervous system, or their muscles.Muscle characteristics of ten sloths (Choloepus hoffmanni and Bradypus tridactylus) were studied by neuromuscular examination, electrophysiological, biochemical, and histological methods. Muscle twitch contraction averages 120 msec and one‐half relaxation time was 108 msec. Muscle contraction and relaxation are extremely sensitive to cold but were unaltered by calcium, quinine or procaine amide.Biochemical studies showed ATPase activity to be extremely low.Ultrastructure conformed closely to that of mammalian twitch fibers.Our data suggest that although muscle mechanics undoubtedly contribute to the slow movements of the sloth, they are not the only rate limiting factor.

Myocardial ultrastructure and electrocardiograms of the sloth (Bradypus tridactylus) under normal and experimental conditions.

AbstractAdult sloths (Bradypus tridactylus) were studied by electrocardiography and by light and electron microscopy under normal conditions and under experimental conditions as provided for by injection of 2,4‐dinitrophenol (DNP) and ether anesthesia. ECG's of the animals indicated heart rates of 45–71/min, which can be considered as the normal heart rate of the sloth under laboratory conditions. Under normal conditions, the contracted ventricular myocardium of the sloth exhibited (a) a wrinkled sarcolemma, (b) the usual pattern of myofibrils and of sarcoplasmic reticulum, (c) small mitochondria with spiked and branched, often anastomosed cristae, including a few small intramitochondrial dark bodies, (d) an amount of sacrcosomes smaller than the amount of myofibrils, (e) many glycogen granules, isolated, in the form of a chain, or as clusters, in subsarcolemmal, intermyofilamentous and perimitochondrial positions, (f) few multivesicular bodies and (g) large flat sections of the transverse tubular system.Injection of DNP (1 mg/kg) caused tachycardia. With ether anesthesia, the ECG showed monophasic action potential of myocardial injury and prolongation of inter or intraventricular condition. Electrically, the sloth's heart responded to hypoxia as do other mammalian hearts.The administration of DNP produced (a) derangement and reduction in number and length of the mitochondrial cristae, (b) disappearance of spikes, connections between the cristae and, consequently, the honeycombed arrangement, (c) increased matricial space in the center of mitochondria which was often filled with a grayish substance, (d) disappearance of small dark intramitochondrial granules, (e) depletion of glycogen particles and (f) few dilations in the sarcoplasmic reticulum.

The lymphatic system of Bradypus tridactylus

AbstractThe lymphatic system of the sloth (Bradypus tridactylus) was described after the study of five specimens captured in Brazil. The lymphatic system was injected with Prussian blue suspension and neoprene latex (the latter followed by partial corrosion). The description includes lymph nodes, lymphatic networks, vessels and trunks. The distribution of these structures follows the general pattern of other Xenarthra, namely, Dasypus, Euphractus and Tamandua. However, the following peculiarities were noted: the submandibular, popliteal and posterior mediastinal ll.nn., the abdominothoracic subcutaneous lymphatic collecting vessels, the true principal lymphatic trunks, the cisterna chyli, and the thoracic duct were missing in Bradypus tridactylus. The mesenteric ll.nn. do not fuse and their efferent vessels intermingle with those originating from the cecocolic ll.nn. forming a mesenteric lymphatic plexus. The lymphatic vessels arising from the submucous network of the descending and sigmoid colon are arranged as parallel lamellae similar to those in Dasypus. The efferent collecting vessels from several abdominal organs ultimately empty directly in the inferior vena cava and its trunks of origin and those coming from the bronchial ll.nn. lead to the azygos vein. This feature reminds one of the conditions described in some monkeys. The mesenteric postlymphonodal plexus is well developed and because of the absence of intercalated lymph nodes in the labrinthine circulation it resembles that of amphibia and birds.

Somatic afferent areas I and II of dog's cerebral cortex.

ArticlesSOMATIC AFFERENT AREAS I AND II OF DOG'S CEREBRAL CORTEXTeresa Pinto Hamuy, Reg. B. Bromiley, and Clinton N. WoolseyTeresa Pinto Hamuy, Reg. B. Bromiley, and Clinton N. WoolseyPublished Online:01 Nov 1956https://doi.org/10.1152/jn.1956.19.6.485MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByThe history of the neurophysiology and neurology of the parietal lobeHemispheric Mapping of Secondary Somatosensory Cortex in the RatAlexander M. Benison, David M. Rector, and Daniel S. Barth1 January 2007 | Journal of Neurophysiology, Vol. 97, No. 1Functional Imaging with Intraoperative Ultrasound: Detection of Somatosensory Cortex in Dogs with Color-duplex SonographyNeurosurgery, Vol. 56, No. 2Connections of the posterior thalamic region with the auditory ectosylvian cortex in the dog24 October 2003 | The Journal of Comparative Neurology, Vol. 467, No. 2Glossopharyngeal Nerve Evoked Potentials after Stimulation of the Posterior Part of the Tongue in DogsNeurosurgery, Vol. 51, No. 4Polysensory evoked potentials in rat parietotemporal cortex: combined auditory and somatosensory responsesBrain Research, Vol. 642, No. 1-2Stimulation of three areas of the primary motor cortex interrupts micturition in dogsJournal of the Autonomic Nervous System, Vol. 38, No. 3Fifth somatosensory cortex (SV) representation of the whole body surface in the medial bank of the anterior suprasylvian sulcus of the catNeuroscience Research, Vol. 11, No. 3Effects of halothane dose and stimulus rate on canine spinal, far-field and near-field somatosensory evoked potentialsElectroencephalography and Clinical Neurophysiology, Vol. 69, No. 3The projection pathway from the tooth pulp to the ipsilateral first somatosensory cortex (SI) in the catArchives of Oral Biology, Vol. 33, No. 4The representation of the oral structures in the first somatosensory cortex of the catBrain Research, Vol. 409, No. 1Corticostriate projections from the primary motor cortex in the dogBrain Research, Vol. 209, No. 2Motor cortex development in the dog. Some cortical stimulation and behavioral dataNeuroscience, Vol. 3, No. 1Barbiturate spindle activity in the thalamic lateral ventro-posterior nucleus and the second somato-sensory area of the cortexBrain Research, Vol. 98, No. 3Sensory and motor representation in the cerebral cortex of the three-toed sloth (Bradypus tridactylus)Brain Research, Vol. 90, No. 2The general organization of somatotopic projections to SII cerebral neocortex in the catBrain Research, Vol. 44, No. 2Pattern of localization in ‘precentral’ motor cortex of raccoonBrain Research, Vol. 11, No. 3A conditioned reflex study of sensory defects caused by cortical somatosensory ablationsPhysiology & Behavior, Vol. 2, No. 1 More from this issue > Volume 19Issue 6November 1956Pages 485-499 https://doi.org/10.1152/jn.1956.19.6.485PubMed13377199History Published online 1 November 1956 Published in print 1 November 1956 Metrics

Notas sôbre a evolução do virus vacínico em animais silvestres da fauna brasileira

A note on the evolution of cow-pox virus in wild animals of Brazilian fauna. We have tried the sensibility of wild animals of Brazilian fauna to the cow-pox virus. The following specimens were submitted to experiences: Procyon cancrivorus, Hydrochoerus capybara, Cavea aperea, Coendu villosus, Didelphis aurita, Bradypus tridactylus, Euphractus sexcintus, Tamandua tetradactylus, Nasua narica, Dasyprocta aguti and Testudo tabulata. In all these animals, - excepting Bradypus tridactylus - we have obtained an infection with incubation (five days), aspect and duration similar to cow-pox of the laboratorial animals (calf and rabbit). In the Bradypus tridactylus howewer, the incubation was very long. Only after 30 days of inoculation we verified the infection with the formation of vesiculae and postulae.

Visual areas I and II of cerebral cortex of rabbit.

Visual areas I and II of cerebral cortex of rabbit.