Ultrastructural characteristics of in vitro parasite-lymphocyte behaviour in invasions with Theileria annulata and Theileria parva

Host-parasite relationships have been studied by electron microscopy using glutaraldehyde-OsO4-fixed pellets of lymphoid cultures infected in vitro by Theileria annulata and T. parva. Intracellular presence of the parasite resulted in a progressive and marked lymphoblastoid transformation. The schizont stage periodically provoked the formation of, and adopted an intimate association with, cytoplasmic annulate lamellae in the interphase cell. Annulate lamellae developed from the outer nuclear membrane of the host cell by a delamination process and were taken into the cytoplasmic matrix of the schizont by phagotrophy through the cytostome. Schizont nuclei themselves were seen to divide at the prometaphase stage of host cell mitosis, the division being characterized by the development of intranuclear spindle microtubules anchored in spindle pole bodies. A hypothesis is propounded that Theileria parasites, consequent on interiorization, provoke the blastoid transformation and the formation of annulate lamellae through the influence of components of their genomic material on host cell deoxyribonucleic acid (DNA) and that the annulate lamellae represent a species of messenger ribonucleic acid (mRNA) and serve as a monitoring device for the schizont, facilitating the accurate timing of the host cell cyclical events.     

Ultrastructural and ultracytochemical cyclic changes in the bovine uterine tube (oviduct) epithelium.

Ultrastructural and ultracytochemical features of the uterine tube (oviduct) infundibulum were studied in 8 Hereford cows, which were slaughtered in pairs on days 1 (estrus), 3, 9 or 10, and 18 of the estrous cycle. Fibrous granules (60 to 80 nm), which are supposedly related to basal body replication, were observed in the apical cytoplasm of ciliated cells. Close association between basal bodies and fibrous granules was apparent, especially during the follicular phase. Cilia were observed throughout of estrous cycle, although degeneration of cilia was not observed at any phase of the cycle. Prominent, striated rootlets were observed during both the follicular and luteal phases of the cycle. Maximum secretory cell differentiation was apparent during the follicular phase, at which time these cells were characterized by having a well-developed, rough endoplasmic reticulum with dilated cisternae, numerous ribosomes, and secretory granules of varied size and density. A prominent feature of the secretory granules was their membranous structure, consisting of concentric lamellae of equal dimensions. During the luteal phase, cytoplasmic protrusions were prominent, and extruded nuclei along with other cytoplasmic organelles were present in the tubal lumen. The presence of a well-developed, rough endoplasmic reticulum and numerous secretory granules during the follicular phase indicates that secretory activity of the uterine tube infundibulum may be stimulated by estrogen. During estrus, the cytoplasm of the stromal cells displayed abundant, rough endoplasmic reticulum with dilated cisternae. The increased and extensively dilated rough endoplasmic reticulum at the time of estrus probably indicates increased protein synthesis by the stromal cells. The presence of adenosine triphosphatase activity on the membrane of cilia suggests that this enzyme is involved in energy-forming reactions related to the vigorous action of cilia. The presence of acid phosphatase activity on the cell membrane of the epithelium, microvilli, and secretory granules may indicate involvement in the secretory mechanism of the cell.     

Fine structure of the retinal pigment epithelium, Bruch's membrane and choriocapillaris in the ostrich (Struthio camelus)

The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris in the ostrich (Struthio camelus) was investigated by using light microscopy and transmission electron microscopy. In this species, the RPE consisted of a single layer of low columnar cells. The epithelial cells were joined laterally by two type junctions, zonulae occludentes and zonulae adherentes located in the midregion of the cells. These cells displayed numerous deep basal infoldings and thick extensive apical processes, which enclosed the outer segments of the rods. The epithelial cell nuclei were large, vesicular and located basally within the epithelial cells. Smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was scarce. Mitochondria of various shapes were abundant basally while polysomes were plentiful and widespread. In the light-adapted state melanosomes were located in the apical region and in apical processes of the epithelial cells. Myeloid bodies were large, numerous and often showed ribosomes on their outer surface. Bruch's membrane (complexus basalis) was typical pentalaminate throughout the retina, as noted in the majority of other vertebrates. The endothelium of the choriocapillaris facing Bruch's membrane was extremely thin but only moderately fenestrated. Some of the fenestrations displayed a double-layered diaphragm while the majority showed the more typical single-layered diaphragm noted in most species.     

Fine structure of the retinal pigment epithelium, Bruch's membrane and choriocapillaris in the horse

The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in both the tapetal and non-tapetal fundus of the horse eye. In all locations, the RPE consisted of a single layer of low cuboidal cells. The epithelial cells were joined laterally by apically located tight junctions. These cells displayed numerous basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large and located basally. Within the epithelial cells, smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was scarce, polysomes and mitochondria, which often display a ring-shaped structure, were abundant. Melanosomes were abundant in the non-tapetal area but absent in the tapetal area. Bruch's membrane was pentalaminate throughout the retina. The endothelium of the choriocapillaris was heavily fenestrated.     

Fine structure of the retinal pigment epithelium, Bruch's membrane and choriocapillaris in the camel

The morphology of the retinal pigment epithelium (RPE) and closely associated Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in the camel (Camelus dromedarius). The study showed that RPE is composed of a single layer of hexanocuboidal cells that were joined laterally by a series of apically located tight junctions. In addition, adjacent from internal side of cell membrane at the level of tight junctions, an undefined structure which resembled the myofibrillar organization of skeletal muscles in appearance was located. These cells displayed numerous short basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large, vesicular and eccentrically located. Within the epithelial cells, smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was present only in small amounts. Polysomes were also numerous and the mitochondria often displayed a ring-shaped structure. Lipofuscin granules were plentiful in all locations. Bruch's membrane (complexus basalis) was typically pentalaminate throughout the retina. The endothelium of the choriocapillaris facing Bruch's membrane was extremely thin and heavily fenestrated. These fenestrations displayed typical single-layered diaphragm as noted in most species.     

3-D ultrastructural distribution of collagen in human placental villi at term in relation to vascular tree

In order to understand the 3-D distribution of collagen in relation to vascularization, chorionic villi of human placentae, belonging to normal pregnancies at term, were studied by scanning electron microscopy (SEM) after alkali maceration techniques, and by transmission electron microscopy (TEM). The villous tree appeared made of an uninterrupted structure of collagen fibres. The collagen fibres connected the chorionic villi axis with their basal plates and organised differently according to the various levels of villous branching. The collagen of stem villi showed copious fibres. The external fibres (facing the villous surface) were arranged mainly longitudinally. The central core of the villi (inner fibres) were arranged concentrically around the wall of the fetal vessels. Both external and internal fibres formed stratified lamellae or small parallel bundles. The inner core of stem villi showed small holes housing capillary spaces. Mature intermediate and terminal villi showed a scarce amount of collagen arranged in thin concentric layer within the villous core, surrounding numerous dilated capillary and sinusoid spaces.These observations demonstrated that the extracellular matrix of human chorionic villi is highly compartmentalised and shows a variable structural 3-D distribution depending on the branching level of the villous tree, such a distribution ensures the most favourable microenvironment for feto-maternal exchanges and it is likely able to provide a modulated support to the developing chorionic fetal vessels and trophoblastic layer as well.     

Equine laryngeal hemiplegia. Part II. An electron microscopic study of peripheral nerves

The recurrent laryngeal nerves were examined by electron microscopy in five control, four subclinical and four clinical laryngeal hemiplegic horses. In addition, the peroneal nerve was examined in two horses in the latter group. The distally distributed loss of large myelinated fibres in the left recurrent laryngeal nerve seen by light microscopy was confirmed. In addition, active axonal pathology was found to be more evident than indicated by light microscopic investigations. The onion bulb formations observed indicated the repetitive nature of the damaging influence to nerve fibres. Although the pathological changes were most obvious in the distal left recurrent laryngeal nerve, alterations similar in type and distribution were present in other areas of the left and right nerves, and in the distal hindlimb nerves. The observation of fibres with inappropriately thick myelin sheaths relative to their axonal calibre, was confirmed statistically by determining the regressions of axis cylinder perimeter against the number of myelin lamellae. In conclusion, the peripheral nerve pathology of equine laryngeal hemiplegia was demonstrated to be a distally distributed loss of myelinated fibres, with considerable active axonal damage, in conjunction with axonal atrophy. These features suggest that this disease may be classified as a distal axonopathy.     

Degenerative myopathy in turkey breeder hens: a comparative study of normal and affected muscle

The pH of affected tissue within the green lesion characteristic of degenerative myopathy in the supracoracoideus muscle of turkey breeder hens was 7.4 to 7.8 and there was a high concentration of albumin. Histological examination showed that the striations of affected muscle fibres were more pronounced and curved than those of normal fibres. Examination of the affected fibres using the electron microscope showed that the curvature resulted from displacement of groups of myofibrils. The ultrastructure of these myofibrils differed markedly from that of normal muscle. The A‐band was granular and ill‐defined, while extensive degradation of the I‐band and Z‐line was observed. In addition, the sarcoplasmic reticulum was extensively disrupted and mitochondria had degenerated.     

Some segmental features on the structure of the aortic wall of the dog

Structural features of segmental parts of the aorta of the dog were studied by light microscopy (LM) and scanning electron microscopy (SEM). The variability in the wall architecture composition and vascular thickness of the ascending (T2-3 level), thoracic (T7-8 level) and abdominal (L6-7 infrarenal level) segments of the aorta was analysed. Morphological features such as presence of intimal folds, pattern of the medial myoconnective components with segmental variations in the number of elastic lamellae, whose relative number was higher in the thoracic aorta (ascending and descending parts), compared with the abdominal aorta, and a network of connective (stromal) elements formed by elastic and collagen lamellae and fibres in the adventitia were observed. The results were discussed on a histophysiological basis, because small but significant segmental differences had been characterized in the aortic wall structure of the dog.     

Retinal Pigment Epithelial Fine Structure in the Great Blue Heron (Ardea herodias)

The fine structure of the retinal epithelium (RPE), choriocapillaris and Bruch's membrane (complexus basalis) has been studied by light and electron microscopy in the great blue heron (Ardea herodias). In this species the RPE consists of a single layer of cuboidal cells which display numerous basal (scleral) infoldings and plentiful apical (vitreal) processes which surround photoreceptor outer segments. These epithelial cells are joined laterally by a series of tight junctions located in the mid to basal region. Within the epithelial cells, smooth endoplasmic reticulum is very abundant while rough ER is not. Mitochondria (some of which are ring-shaped) and polysomes are abundant. In light-adaptation the RPE nuclei are large vesicular and basally located while the melanosomes of these cells are almost exclusively located within the apical processes. Myeloid bodies are large and numerous and often show ribosomes on their outer surface. Bruch's membrane (complexus basalis) shows the typical pentalaminate structure noted in the majority of vertebrates except teleosts. The choriocapillary endothelium is very thin facing Bruch's membrane but is only moderately fenestrated. The majority of these fenestrations show a single-layered diaphragm but double-layered diaphragms are also noted.     

Retinal Epithelial Fine Structure in the Domestic Cat (Felis catus)

The morphology of the retinal epithelium (RPE) and closely associated choriocapillaris and Bruch's membrane (complexus basalis) has been investigated in the eye of the domestic cat (felis catus) by light and electron microscopy. The RPE consists of a single layer of cuboidal cells joined laterally by apically-located junctional complexes. Basally (sclerally) these cells display numerous infoldings while apically (vitreally) two distinct types of processes enclose photoreceptor outer segments. Internally the large vesicular nucleus is centrally located. Smooth endoplasmic reticulum, mitochondria, polysomes and lysosome-like bodies are abundant. Rough endoplasmic reticulum while present is not plentiful. Over the tapetum lucidum, melanosomes are absent from the RPE cells while in non-tapetal locations melanosomes are large and plentiful. The endothelium of the choriocapillaris is highly fenestrated and these capillaries are deeply indented into the epithelial layer over the tapetum. Bruch's membrane (complexus basalis) is non-tapetal regions is the typical pentalaminate structure noted for most mammals. Over the tapetum however it is reduced to a trilaminate structure and when associated with the indented capillary profiles is further reduced to a single thickened basal lamina.     

Hoof wall wound repair

REASONS FOR PERFORMING STUDY: Surgical stripping of the hoof wall results in a wound that heals remarkabley well. In contrast, lamellae recovering from laminitis are often deformed. Investigating lamellar wound healing may aid understanding of laminitis. OBJECTIVES: To document temporal changes in the lamellar basement membrane (BM), dermis and epidermis after surgery. METHODS: Wall strips were made in the dorsal hoof wall midline of 6 mature horses. Immunohistochemistry was used to document changes in the basement membrane (BM) and detect proliferation of epidermal cells in lamellar tissues harvested at intervals. A conforming metal plate was screwed to the hoof wall to maintain alignment of the wound edges. RESULTS: Wall stripping caused lamellar tips to snap and remain behind in the dermis along with the majority of the lamellar BM and some lamellar basal cells. Three days later the BM was intact and new lamellae had been reconstructed by proliferation of surviving epidermal cells. By 5 days the surface of the stripped zone was covered with yellow epidermis that subsequently thickened and hardened. Eventually the hoof wall deficit was replaced by new wall growing down from the coronet. The conforming metal plate and post operative analgesic ensured minimal lameness. CONCLUSIONS AND POTENTIAL RELEVANCE: In wall stripped lamellae the BM survives virtually intact and is used as a template for proliferating cells, from snapped-off lamellar tips, to migrate and quickly achieve repair to near normality. In laminitis epidermal dysadhesion and lamellar BM destruction occurs and lack of a functional BM template may explain the prolonged and abnormal repair of affected lamellae.     

禽源多杀性巴氏菌外膜蛋白的提取及其对小鼠的免疫原性观察

用EDTA—溶菌酶系统处理无荚膜的5:A型禽多杀性巴氏菌,得到无粘肽层的细胞膜.蔗糖密度梯度离心,将细胞膜分成3部分.琥珀酸脱氢酶、还原型辅酶I-2,6 二氯酚靛酚(NADH-DICP)氧化还原酶和NADH氧化酶的活性以及脂多糖含量测定表明,这3部分分别是细胞内膜、细胞外膜和混合膜.用高压液相色谱法从分离的外膜中提纯外膜蛋白,获得2个主要成分P_1和P_2.将P_1和P_2分别免疫小鼠,其保护率分别为20%和90%.SDS-聚丙烯酰胺凝胶电泳表明,P_2是一种主要的外膜蛋白,分子量为52000.     

Retinal Pigment Epithelial Fine Structure in the American Crow (Corvus brachyrhynchos)

The fine structure of the retinal epithelial (RPE) region has been investigated by light and electron microscopy in the American crow (Corvus brachyrhynchos). In this species the RPE consists of a single layer of cuboidal cells which display numerous deep basal (scleral) infoldings and plentiful apical (vitreai) microvillar processes which surround photoreceptor inner and outer segments. The RPE cells are joined laterally by a series of tight junctions (VERHOEFF'S membrane) located in the mid to basal region. Within the epithelial cells, smooth endoplasmic reticulum is very abundant while rough endoplasmic reticulum (RER) is scarce. Mitochondria of various shapes are abundant basally while polysomes are plentiful and widespread. In the light-adapted state RPE nuclei are large and vesicular and basally located while the melanosomes of these cells are predominantly located with the apical processes indicating photomechanical movements. Myeloid bodies are large and numerous and often have ribosomes on their outer surface. Bruch's membrane (complexus basalis) is typical of avian species in that it is pentalaminate and the lamina densa is displaced near the cho-riocapillaris. The endothelium of the choriocapillaris is thin facing Bruch's membrane but is only moderately fenestrated. Some of these fenestrations display a double-layered diaphragm while the majority show the more typical single-layered diaphragm noted in most species.     

Structure and relationship of the mammillary gore to membrane fibres and initial calcification of the avian Egg Shell 1

1. The interior of the mammillary knob is shown to be composed of: (1) outer shell membrane fibres that penetrate the basal portion of the knob and become associated with (2) The mammillary core, and (3) the bulk calcification of the main knob.

2. The mammillary knob consists of radial crystals which are arranged in a hemisphere on the outer shell membrane fibres, and are composed of a central zone which is a homogeneous solid, crystalline in nature, and an outer heterogeneous vesiculated zone.

3. The walls of the mammillary knob are continuous with the base and sides of the mammillary core radial crystals; the dorso‐central zone of the core crystals are exposed to a cavity that communicates with the upper zones of the mammillary knob and palisade layer via the central channel. The dorsal surface of the core cavity is formed by a layer of unorganised crystals of the mammillary knob proper.

4. Initial calcification of the knob begins at the base and sides of the mammillary core and expands over the organic core as the walls of the knob thicken during subsequent calcification. Incomplete fusion of the central expansions from peripheral knob areas results in the central channel.     

The ultrastructure of the subcommissural organ ependyma of the goat

The cells of pseudostratified columnar ciliated ependyma of the subcommissural organ in the goat were classified into two types on the basis of the distribution of chromatin material and nuclear clefts. Amongst the cell organelles the endoplasmic reticulum was highly developed and formed three types of Nebenkerne systems. The type-I Nebenkerne had spiral concentric lamellae and was associated with round lipid droplets. The type-II Nebenkerne, with widely spaced coils, was expanded towards its central and peripheral parts. The type-III Nebenkerne, composed of a meshwork of lamellae, was modified into a vacuolated form. The concentration of mitochondria was greatly increased towards the basal processes of the ependymal cells. The inclusion bodies included small electron-dense bodies, osmiophilic asteroid droplets, large round to spherical bodies and large round osmiophilic bodies with inner structures.     

PEG胁迫对经60Co-γ辐射无芒雀麦种子的幼苗叶片超微结构的影响

为明确⁶⁰Co-γ射线对干旱条件下无芒雀麦（Bromus inermis）叶片的影响,从而为无芒雀麦利用辐射进行抗旱育种提供理论依据,本试验应用透射电镜观察聚乙二醇（Polyethylene glycol,PEG）模拟干旱胁迫下的⁶⁰Co-γ射线辐射无芒雀麦的叶片细胞,比较辐射对无芒雀麦叶片细胞、叶绿体、线粒体的形态和超微结构的影响。试验结果表明：未受辐射和PEG胁迫的无芒雀麦叶片细胞形态规则,叶绿体基粒片层和基质片层多且有序,线粒体膜完整,内嵴清晰,基质浓厚。10% PEG胁迫50 Gy辐射处理组叶片细胞扭曲最严重,形态不规则,细胞壁厚度不均,质膜内陷,有轻微质壁分离。10%和20% PEG胁迫下辐射剂量为50 Gy时,叶绿体和线粒体形态和超微结构受影响程度较轻,随着干旱胁迫强度和辐照剂量的增加,叶绿体和线粒体超微结构受损伤程度增强;20% PEG胁迫下辐射剂量为200 Gy时,叶绿体膜有不同程度破损,基粒片层排列的紊乱性增加,部分基粒片层不清晰,基质类囊体片层结构清晰,可见少量淀粉粒;线粒体膜破损比较严重,内嵴减少,排列不规则,基质较浅。可见,不同⁶⁰Co-γ射线辐射剂量可对无芒雀麦叶片叶绿体和线粒体超微结构产生不同程度的影响,在利用⁶⁰Co-γ射线辐射进行无芒雀麦耐旱性育种时,可选择50 Gy低辐射剂量结合20% PEG模拟干旱胁迫进行抗旱性突变体的筛选。     

The preparation of nucleated erythrocyte ghosts from avian erythrocytes

A method is described for the preparation of erythrocyte ghosts, which are haemoglobin‐depleted, from domestic fowl and turkey erythrocytes. These erythrocyte ghosts retain their ellipsoid shape and their nuclei, which are shown to possess the typical double nuclear membrane. In the cytoplasmic compartment of the ghosts, mitochondria have been clearly observed. There is little or no indication of endoplasmic reticulum. Filamentous structures have been seen adhering to the outer nuclear membrane, the mitochondria and the inner surface of the plasma membrane. These filaments may extend between the plasma membrane and the surfaces of the nucleus and mitochondria, thereby providing a form of structural anchorage for these organelles. It is a consistent observation that the nucleus of the intact erythrocyte and its ghost always occupies a central position, so some structure must be holding the nucleus otherwise one would expect to occasionally find it positioned off‐centre. Significantly, very few of the filament structures are observed at the extremities of the avian erythrocyte ghost, well away from the nucleus.     

Histomorphology of the stomach, proventriculus and ventriculus of the red jungle fowl

The cranial chamber (proventriculus) and caudal chamber (ventriculus) of the stomach of the Red jungle fowl (Gallus gallus spadiceus) were examined by means of light microscopy. Both chambers presented folds of the tunica mucosa lined by a simple prismatic epithelium that was positive for neutral mucin. Simple tubular glands occupied the lamina propria of both chambers; in the ventriculus of older birds, they showed a coiled base. These ventricular glands were lined by simple cuboidal cells represented by the chief cells and a few large basal cells. The luminal and tubular koilin rodlets and folds of the ventriculus were positive to periodic acid Schiff (PAS) stain. The proventricular glands were situated between the inner and outer layers of the lamina muscularis mucosae. Cells lining the tubulo-alveolar units of the proventricular glands showed a dentate appearance. Vacuoles were not observed, and the cells were negative for Alcian-PAS stain. The tunica submucosa was very thin in the proventricular wall. In the ventriculus, it was not separated from the lamina propria owing to the absence of any lamina muscularis mucosae. The tunica muscularis of the proventriculus was formed by a thick inner layer of circular smooth muscle fibres and a thin outer layer of longitudinal fibres. In addition to these layers, oblique muscle fibres formed the most internal layer of the tunica muscularis in the ventriculus.