38 research outputs found
Liver and gallbladder morphology of the juvenile Nile crocodile, Crocodylus niloticus (Laurenti, 1768)
This investigation illustrates the topography, gross anatomy, histology and ultrastructure of the liver and gallbladder of the Nile crocodile in order to fill the gap that exists in the literature regarding this important crocodilian. For the topographical and macroscopical descriptions the livers and gallbladders were obtained from the carcasses of slaughtered juvenile Nile crocodiles. Perfusion and immersion fixation of tissues for histology and transmission electron microscopy were performed on juvenile Nile crocodiles donated to the university. Published descriptions of other vertebrates were inevitably relied upon for comparison due to the lack of information on these two organs of the Nile crocodile. The liver was located in its own coelomic cavity with the post-pulmonary and the post-hepatic membranes intimately associated with the cranial and caudal surfaces of the bi-lobed liver respectively. The right lobe was larger than the left lobe and they were located at the level of the third to seventh intercostal spaces with their extremities extending to the ninth intercostal space. The triangular shaped liver lobes were joined dorso-medially by a narrow isthmus consisting of liver tissue. The liver was covered by Glisson’s capsule. Central veins, sinusoids and portal tracts were distributed haphazardly with no visible lobulation. The parenchymal component occupied the largest part of the liver and was formed by anastomosing and branching cell cords consisting of two-cell-thick plates in the longitudinal sectional plane and at least five hepatocytes in the cross-sectional plane. Central bile canaliculi contained microvilli originating from apical hepatocyte surfaces and were sealed off by junctional complexes. Hemosiderin granules, bile pigments, melanin pigments, lipid droplets, cholesterol ester slits and glycogen granules were observed in addition to the normal hepatic cytoplasmic organelles. Non-parenchymal cells consisted of endothelial cells, Kupffer cells, stellate cells and pit cells localized in and around the angular sinusoids. The space of Disse existed between endothelial cells and the base of the hepatocytes which was lined by microvilli. Endothelial cells were flat cells with long fenestrated cytoplasmic extensions that lined the sinusoidal wall and contained numerous endocytotic vesicles and many lysosomes. Pleomorphic Kupffer cells were located in the sinusoidal lumen, in the space of Disse and within groups of hepatocytes. They were often situated between groups of hepatocytes, connecting two adjacent sinusoids. Large phagosomes were present in the Kupffer cells and contained a combination of melanin and hemosiderin granules as well as ceroid. Phagocytosis of apoptotic and dying cells was evident. Conspicuous groups of membrane-bound tubular organelles with a filamentous or crystalline interior were present in the Kupffer cells. Stellate cells occupied a subendothelial position in the space of Disse and contained prominent lipid droplets that indented the nuclei. A solitary cilium was infrequently found projecting into the space of Disse. Myofibroblastic cells were found in the same region as stellate cells. Pit cells with indented eccentric nuclei were found in the sinusoidal lumen and in close contact with endothelial and Kupffer cells. Numerous small electron-dense membrane-bound cytoplasmic granules were present. Occasional intercalated cells resembling lymphocytes were seen in the space of Disse and forming part of the groups of hepatocytes. Glisson’s capsule extended collagenous trabeculae into the parenchymal interior and variably sized trabeculae randomly traversed the liver tissue. Portal tracts were enmeshed by a collagenous network that contained fibroblasts, lymphocytes, plasma cells and phagocytes. Portal triads consisted of branches of the portal vein, hepatic artery and bile duct with lymphatic vessels sometimes in accompaniment. Reticular fibres were positioned around hepatocyte tubules and a basal lamina supported the hepatocytes adjacent to Glisson’s capsule. Occasional unmyelinated nerve axons were present. The isthmus contained liver tissue with similar parenchymal and a non-parenchymal components. Three anatomical zones were identified in the pouch-like gallbladder that was attached caudally to the right liver lobe in the dorso-medial region. The gallbladder wall consisted of pseudostratified columnar epithelium, a lamina propria, a muscularis externa and a serosal layer. The accumulation of apical secretory granules, apical bulging, exocytosis of mucous granules and the desquamation of the apical portions of the epithelial cells into the lumen indicated different stages of the mucus secretory cycle. CopyrightDissertation (MSc)--University of Pretoria, 2012.Anatomy and PhysiologyUnrestricte
Kupffer cell structure in the juvenile Nile crocodile, Crocodylus niloticus
The morphology of Kupffer cells was
examined in the liver of the juvenile Nile crocodile
using light microscopy and transmission electron
microscopy. Pleomorphic Kupffer cells were located in
the sinusoids, in the space of Disse, in the hepatic
parenchyma and often connected adjacent sinusoids.
The cell surfaces were irregular due to the presence of
filopodia and lamelliapodia with phagocytosis of white
blood cells, red blood cells and thrombocytes being evident.
The cells were in close contact with endothelial
cells and pit cells in the sinusoidal lumen and with
stellate cells in the space of Disse. The cytoplasm contained
large phagosomes comprising a combination of
ceroid pigment, melanosomes and siderosomes. The
nuclei were often indented and eccentrically placed due
to the presence of the phagosomes. Conspicuous clusters
of membrane-bound tubular organelles with a filamentous
or crystalline interior were observed in the
cytoplasm. The clusters were sometimes separated into
smaller groups around phagosomes. A clear zone
existed between the limiting membrane and the interior
of these tubular organelles with the electron-dense
interior profiles being, respectively, circular, angular or
divided. The tubular organelles have not previously
been described in Kupffer cells and possibly represent
lysosomes with specialized functions. Mitochondria,
microtubules, Golgi profiles, granular and smooth endoplasmic
reticulum, and a few cytoplasmic lipid droplets
were also present. The presence of the tubular organelles
and the occurrence of the Kupffer cells in different
locations in the liver of the juvenile Nile crocodile are
indicative of particularly active and mobile cells.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-4687hb201
Paraquat intoxication and associated pathological findings in three dogs in South Africa
Paraquat is a bipyridylium non-selective contact herbicide commonly used worldwide. When
ingestion occurs by humans and animals either accidentally, intentionally or maliciously,
paraquat selectively accumulates in the lungs resulting in the production of oxygen-free
radicals, causing membrane damage and cell death. Intoxicated subjects typically show
progressive and fatal pulmonary haemorrhage, collapse and oedema. In individuals surviving
the acute phase, pulmonary fibrosis develops. Gastrointestinal-, renal- and central nervous
system clinical signs may also occur. Owing to the lack of effective treatment and absence of an
antidote, the prognosis is poor. The clinical presentation, clinicopathological findings and
treatment are briefly described of three dogs from one South African household, intoxicated
with paraquat. Macroscopic and microscopic lesions in one dog that was necropsied, as well
as pulmonary ultrastructure are detailed and illustrated for academic reference. All dogs
presented with tachypnoea and dyspnoea 2–3 days after accidental paraquat ingestion.
Treatment was aimed at reducing gastrointestinal absorption, enhancing elimination by
diuresis and avoiding further oxidative damage by administration of antioxidants. All dogs,
however, became progressively hypoxic despite treatment and were euthanised. Paraquat
toxicity should be a differential diagnosis in dogs with unexplained progressive respiratory
and gastrointestinal signs and renal failure. The local veterinary profession should be aware of
accidental or intentional paraquat toxicity of animals. Existing literature, variations possible in
canine clinical signs, measured parameters, lesions, as well as possible treatments, promising
experimental antidotes and management options are discussed.http://www.jsava.co.zaam2016Animal and Wildlife SciencesParaclinical Science
Infestation of Mangifera indica by the mango gall fly, Procontarinia matteiana, (Kieffer & Cecconi) (Diptera: Cecidomyiidae)
Mango gall fly (Procontarinia matteiana Kieffer&Cecconi, 1906) is an orchard pest that infests
flush leaves of mango, forming wart-like structures on the leaves. Serious outbreaks may
result in reduced fruit yield. A natural parasite (Chrysonotomyia pulcherimma Kerrich, 1970)
of the gall fly lays its eggs inside the gall and the larvae feed on the gall fly. Mango cultivars
present varying susceptibilities to gall fly infestation, with cultivars ranging from completely
resistant, highly susceptible to intermediate stages where pseudo-galls are formed. The
latter cultivars are ovipositioned by the gall fly, but secondary metabolites within the leaves
possibly halt the development, thereby preventing the development of true galls. Microscopy
was used to identify characteristic features of the gall fly and its parasite inside the gall,
to study the development of the insects and to distinguish them. Evidence was obtained that
the use of insecticides curbs the development of the larvae. Tissue development within true
and pseudo-galls was studied to provide insights into the role of secondary plant metabolites
in arresting true gall formation. This study will contribute to a more holistic approach to
pest management of mango.http://www.journals.co.za/ej/ejour_ento.htmlam2013ab201
Ultrastructure of Sarcocystis bertrami sarcocysts from a naturally infected donkey (Equus asinus) from Egypt
There is considerable confusion concerning Sarcocystis species in equids. Little is known of Sarcocystis infections in donkeys (Equus asinus). Here we describe the structure of Sarcocystis bertrami-like from the donkey by light microscopy (LM) and transmission electron microscopy (TEM). Nineteen sarcocysts from the tongue of a donkey from Egypt were studied both by LM and TEM. By LM, all sarcocysts had variably shaped and sized projections on the sarcocyst walls, giving it a thin-walled to thick-walled appearance, depending on individual sarcocyst and plane of section. By TEM, sarcocysts walls had villar protrusions (vp) of type 11. The sarcocyst wall had conical to slender vp, up to 6 µm long and 1 µm wide; the vp were folded over the sarcocyst wall. The total thickness of the sarcocyst wall with ground substance layer (gs) was 1-3 µm. The vp had microtubules (mt) that originated deeper in the gs and continued up to the tip. The apical part of the vp had electron dense granules. The mt were configured into 3 types: a tuft of electron dense mt1 extending the entire length of the vp with a tuft of medium electron dense mt2 appearing in parallel, and fine mt3 present only in the villar tips. The gs was mainly smooth with few indistinct granules. All sarcocysts were mature and contained metrocytes and bradyzoites. Bradyzoites were approximately 11-15 × 2-3 µm in size with typical organelles.http://journals.cambridge.org/action/displayJournal?jid=PAR2016-07-30hb201
Molecular detection of yaba monkey tumor virus from a vervet monkey
Yaba monkey tumour virus (YMTV) was first diagnosed in a colony of captive rhesus monkeys (Macaca mulatta) in Yaba, Nigeria. It has been implicated as the cause of cutaneous nodules in wild baboons (Papio species), rhesus monkeys (Macaca mulatta) and cynomolgus monkeys (Macaca fascicularis). This article reports a case of cutaneous pox lesions caused by YMTV in a free-ranging adult female vervet monkey (Chlorocebus pygerythrus) from the Umkomaas coastal area in South Africa. The virus was identified by molecular sequencing from fragments of the insulin metalloprotease-like protein and intracellular mature virion membrane protein as well as the DNA polymerase genes. Phylogenetic analyses of these gene regions revealed a 99% similarity of the sample to YMTV. Although human disease caused by YMTV is normally mild, it is recommended that persons in contact with non-human primates in the area of Umkomaas who develop cutaneous lesions should inform their doctors of the possibility of this infection. The extent and significance of the virus to human and non-human primates in South Africa are not known. To the authors’ knowledge, this is the first diagnosis of YMTV in South Africa and in vervet monkeys
Pathology of fatal lineage 1 and 2 West Nile virus infections in horses in South Africa
Since 2007, West Nile virus (WNV) has been reported in South African horses, causing severe
neurological signs. All cases were of lineage 2, except for one case that clustered with lineage
1 viruses. In the present study, gross and microscopic lesions of six South African lineage
2-infected horses and the one lineage 1 case are described. Diagnoses were confirmed by
real-time reverse-transcriptase polymerase chain reaction (RT-PCR) of central nervous system
(CNS) tissue and one by RT-PCR of a brain virus isolate. The CNS of all cases was negative by
RT-PCR or immunohistochemistry (IHC) for African horse sickness (AHS), equine encephalosis
virus, equine herpes viruses 1 and 4, other zoonotic flaviviruses, alphaviruses, and shunivirus,
and either by immunofluorescence or IHC for rabies. Gross visceral lesions were nonspecific but
often mimicked those of AHS. The CNS histopathology of WNV lineage 2 cases resembled the
nonsuppurative polioencephalomyelitis reported in the Northern Hemisphere lineage 1 and
recent Hungarian lineage 2 cases. Occasional meningitis, focal spinal ventral horn poliomalacia,
dorsal and lateral horn poliomyelitis, leucomyelitis, asymmetrical ventral motor spinal neuritis
and frequent olfactory region involvement were also seen. Lineage 2 cases displayed marked
variations in CNS lesion severity, type and distribution, and suggested various viral entry
routes into the CNS, based on findings in experimental mice and hamsters. Lineage 1 lesions
were comparable to the milder lineage 2 cases. West Nile virus IHC on CNS sections with
marked lesions from all cases elicited only two antigen-positive cells in the olfactory cortex
of one case. The presence in the CNS of T-lymphocytes, B-lymphocytes, plasma cells and
macrophage-monocytes was confirmed by cluster of differentiation (CD) 3, CD20, multiple
myeloma oncogene 1 (MUM1) and macrophage (MAC) 387 IHC.http://www.jsava.co.zaam201
Comparative pathology of neurovirulent lineage 1 (NY99/385) and lineage 2 (SPU93/01) West Nile virus Infections in BALBc mice
The pathology in mice infected with neurovirulent South African lineage 2 West Nile virus (WNV) strains has not previously been
described. Three- to 4-month-old male BALBc mice were infected with South African neurovirulent lineage 2 (SPU93/01) or lineage
1 (NY385/99) WNV strains and the gross and microscopic central nervous system (CNS) and extra-CNS pathology of both
investigated and compared. Mice infected with both lineages showed similar illness, paralysis, and death from days 7 to 11 postinfection
(PI). Two survivors of each lineage were euthanized on day 21 PI. WNV infection was confirmed by nested real-time
reverse transcription polymerase chain reaction of tissues, mostly brain, in the majority of mice euthanized sick or that died and
in 1 healthy lineage 2 survivor. Gross lesions caused by both lineages were identical and included marked gastric and proximal
small intestinal fluid distension as described in a previous mouse study, but intestinal microscopic lesions differed. CNS lesions
were subtle. Immunohistochemical (IHC)–positive labeling for WNV E protein was found in neurons multifocally in the brain
of 3 lineage 1–infected and 3 lineage 2–infected mice from days 9 to 11 PI, 4 of these including brainstem neurons, and of cecal
myenteric ganglion neurons in 1 lineage 2–infected day 8 PI mouse. Findings supported hypotheses in hamsters that gastrointestinal
lesions are likely of brainstem origin. Ultrastructurally, virus-associated cytoplasmic vesicular or crystalline structures, or
amorphous structures, were found to label IHC positive in control-positive avian cardiomyocytes and mouse thalamic neurons,
respectively, and WNV-like 50-nm particles, which were scarce, did not label.National Research Foundation of South Africa and Pfizer Animal Health. Section of Pathology of the Department of Paraclinical Sciences of the Faculty of Veterinary Science, University of Pretoria, South Africa.http://vet.sagepub.comhb201
A review of sarcocystosis in camels and redescription of Sarcocystis cameli and Sarcocystis ippeni sarcocysts from the one-humped camel (Camelus dromedarius)
There is considerable confusion concerning Sarcocystis species in camels. Five species:
Sarcocystis cameli, S. ippeni, S. camelicanis, S. camelocanis, and S. miescheri were named with
inadequate descriptions and no type specimens. Here, we review literature on sarcocystosis in
camels worldwide and redescribe structure of S. cameli and S. ippeni sarcocysts by light and
transmission electron microscopy (LM, TEM). Eight sarcocysts from the esophagi of two camels
(Camelus dromedarius) from Egypt were studied. By LM all sarcocysts were thin walled with barely visible projections on the cyst walls. By TEM, two structurally distinct sarcocysts were
recognized by unique villar protrusions (vp) not found in sarcocysts from any other host.
Sarcocysts of S. cameli had vp of type 9j. The sarcocyst wall had upright slender vp, up to 3.0
ÎĽm long and 0.5 ÎĽm wide; the total thickness of the sarcocyst wall with ground substance layer
(gs) was 3.5 ÎĽm. On each vp there were rows of knob-like protrusions that appeared to be
interconnected. The vp had microtubules that originated at mid point of the gs and continued up
to the tip; microtubules were smooth, without any granules or dense areas. Bradyzoites were
approximately 14-15 x 3-4 ÎĽm in size with typical organelles. Sarcocystis ippeni sarcocysts had
type 32 sarcocyst wall characterized by conical villar protrusions with an electron dense knob.
The total thickness of the sarcocyst wall (from the base of gs to vp tip) was 2.3-3.0 ÎĽm. The vp
were up to 1.2 ÎĽm wide at the base and 0.25 ÎĽm at the tip. Microtubules in vp originated at
midpoint of gs and continued up to tip; microtubules were criss-crossed, smooth and without
granules or dense areas. Bradyzoites were 12.0-13.5 x 2.0-3.0 ÎĽm in size. Sarcocystis
camelicanis, S. camelocanis, and S. miescheri are considered invalid.R. Calero-Bernal is a postdoctoral fellow (ref. PO12010) funded by the Department of
Employment and Innovation of the Regional Government of Extremadura (Spain) and the
European Social Fund.http://journals.cambridge.org/action/displayJournal?jid=PAR2016-01-31hb201