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.     

Fine Structure of the Choriocapillaris, Bruch''s Membrane and Retinal Epithelium of the Cow

The fine structure of the choriocapillaris, Bruch's membrane and retinal epithelium was investigated in both the tapetal and non-tapetal fundus of the bovine eye. In ail locations the retinal epithelium consists of a single layer of cuboidal cells. The epithelial cells are joined laterally by apically located tight junctions and throughout the retina display numerous basal infoldings and fine apical processes which enclose rod outer segments. All retinal epithelial cells are rich in smooth endoplasmic reticulum and mitochondria and contain phagosomes. Although not as abundant, profiles of rough endoplasmic reticulum and polysomes are also noted in all locations. In non-tapetal areas, melano-somes are numerous whereas over the central tapetum fibrosum they are absent. The absence of melanosomes over a functional tapetum is to be expected. While lysosomes are present throughout the epithelial layer, over the tapetal region they appear to be more numerous. The apparent increase in lysosomal numbers in this location may indicate an enhanced shedding of outer segment material over the tapetum. Although some retinal epithelial cells are modified to accomodate a tapetum lucidum their morphology is basically similar throughout the retina and probably indicates that ail regions of the retinal epithelium are capable of the normal functions of this indispensible retinal layer. The choriocapillaris is heavily fenestrated on the border facing the retina and overlying the tapetum also displays fenestrae on its choroidal edge. Bruch's membrane ( complexus basalis ) is pentalaminate throughout the retina and is slightly thicker in the posterior fundus.     

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.     

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.     

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 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.     

Retinal Pigment Epithelial Fine Structure in the Red-Tailed Hawk (Buto jamaicensis)

As part of a comparative morphological study, the fine structure of the retinal epithelium (RPE), choriocapillaris and Bruch's membrane (complexus basalis) has been studied by electron microscopy in the red-tailed hawk (Buteo jamaicensis). In this species the RPE consists of a single layer of low cuboidal cells which display numerous basal (scleral) infoldings and extensive apical (vitreal) processes which interdigitate with photoreceptor outer segments. These epithelial cells are joined laterally by a series of basally located tight junctions. Internally SER is the most abundant cell organelle while only small amounts of RER are present. Polysomes are however abundant as are mitochondria. The RPE cell nucleus is large and vesicular. Melanosomes are mainly located in the apical processes of the RPE cells in light-adaptation. Myeloid bodies are large and numerous in light-adaptation and often show ribosomes on their outer border. Bruch's membrane (complexus basalis) shows the typical pentalaminate structure noted in most vertebrates but with only a poorly defined central elastic layer. The endothelium of the choriocapillaris is very thin facing the RPE but is only moderately fenestrated. The choriocapillaris in this species is unusual however in that many of the fenestrae show a double-layered diaphragm.     

Ultrastructural studies on the pancreatic acini in duck (Anas boscas) and pigeon (Columba livia)

The aim of this research work was to study the histological structure of the pancreatic acini by transmission electron microscope in two avian species, duck and pigeon. The specimens were collected and processed for electron microscopic study. The results showed that the acini of the two avian species were two types; the first one was an electron dense and the second one an electron lucent. The light acinar cells were larger in size than the dark cells. These cells contained centrally located ovoid nuclei with prominent nucleoli and abundant euchromatin. The cytoplasm was electron lucent, with many rough endoplasmic reticulum, polymorphic mitochondria. Numerous zymogen granules were distributed in the basal part and around the nucleus, so these cells considered active cells. The dark acinar cells were characterized by an electron dense cytoplasm. The most prominent cell organelle in these cells were the zymogen granules that appeared in different sizes while other organelles as mitochondria, and rough endoplasmic reticulum were inconspicuous or few, so these cells were considered as inactive cells. The nucleus with indented nuclear membrane located centrally with prominent nucleoli and abundant heterochromatin. Prominent intercellular spaces between the individual acinar cells, as well as well-developed basement membrane separating the electron dense cells and the lumen contained the secretion between acinar cells. It could be concluded that the acinar cells in ducks and pigeons were divided into two types, that is, light and dark acinar cells which mainly attributed to the activity of these cells.     

Ophthalmoscopic characteristics in sheep and goats: comparative study

The ocular fundus was examined in 40 goat eyes and 40 sheep eyes by studying ophthalmoscopic characteristics and retinograms. Similarities and differing characteristics were described. In common: tapetal colour; peripheral yellowish area surrounding the Winslow stars; unpigmented areas in the non-tapetal zone; a great amount of myelin in the optic disc; the Bergmeister's papilla and the holoangiotic retinal vascular pattern. Differences: big size of the Winslow stars in goats; myelinizated fibre over the non-tapetal zone in sheep; shape, position and myelin distribution of the optic disc; and the presence of a 'primary artery' in goats.     

Morphometric and ultrastructural study of postnatal lung growth and development in calves

The objectives of this study were to characterize basic patterns of postnatal lung growth in 1- to 150-day-old Holstein calves and to identify periods of accelerated lung growth and times of epithelial cell development that might correlate with periods of heightened susceptibility to pulmonary injury by infective agents and dietary toxins. Calves had fully developed alveoli at birth. There was an age-associated increase in total alveolar surface area and alveolar number, which was most marked in calves older than 30 days. Lung volume and body weight increases were also most marked when calves were older than 30 days. Mean bronchiolar cross-sectional area increased significantly (P less than 0.05) with age, and there was a significant (P less than 0.05) decrease in the percentage of terminal bronchioles with diameters less than 3 x 10(4) microns between 1 and 150 days. In newborn calves, nonciliated bronchiolar epithelial cells retained fetal characteristics of differentiation, including abundant cytoplasmic glycogen and sparse agranular endoplasmic reticulum. Glycogen deposits were depleted, and agranular endoplasmic reticulum was developed in nonciliated cells by the time calves were 30 days old. We concluded that bronchiolar epithelium in calves is well differentiated by the time they are 30 days old and that lung growth in calves raised in semi-isolation begins most rapidly when calves are approximately 30 days old.     

Structural and ultrastructural characteristics of interrenal gland and chromaffin cell of matrinxã, Brycon cephalus Gunther 1869 (Teleostei-Characidae)

This work presents the structure and ultrastructure of the interrenal gland and chromaffin cells, as well as the morphology of the head kidney of Brycon cephalus. The head kidney is composed of fused bilateral lobes located anterior to the swim bladder and ventrolateral to the spinal column. The parenchyma revealed lympho-haematopoietic tissue, melano-macrophage centres, interrenal gland and chromaffin cells. The interrenal gland consisted of cords or strands of cells grouped around the posterior cardinal vein and their branches. Chromaffin cells are found in small groups, closely associated with the interrenal gland and/or under the endothelium of the posterior cardinal vein. So far, the ultrastructural analysis has revealed only one interrenal cell type which contained abundant smooth endoplasmic reticulum and numerous mitochondria with tubulo-vesicular cristae, characteristic of steroid-producing cells. Two types of chromaffin cells were observed. The first type was characterized by the presence of vesicles with round, strongly electron-dense granules, which were eccentrically located. Such cells were interpreted as noradrenaline cells. Meanwhile, cells which contained smaller vesicles and electron-lucent granules, with a small halo separating the granule from the vesicular limiting membrane, were identified as adrenaline cells.     

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.     

Ultrastructure of the thyroid gland of the one-humped camel (Camelus dromedarius)

Follicular epithelium of the thyroid gland of the one-humped camel was examined by light and electron microscopy. It consisted of a single type of epithelial cell which varied from flattened to columnar in shape. Follicular epithelial cells were characterized by the presence of markedly dilated cisternae of rough-surfaced endoplasmic reticulum, well developed Golgi apparatus, abundant small vesicles (150 nm to 200 nm in diameter) in the apical cytoplasm, and electron-dense colloid droplets measuring from 250 nm to 1600 nm. Follicular epithelial cells frequently showed apocrine secretion into colloidal lumens. Apocrine protrusions with smooth surface were dome-like or balloon-like structures and contained a fine granular matrix. These findings indicate that the morphological features of the follicular epithelial cells of the thyroid gland of the camel are essentially similar to those of mammals except for the presence of apocrine secretion, which is unique to the camel.     

Fine structure of the oesophageal and gastric glands of the red-legged pan frog Kassina maculata Dumeril

Oesophageal and gastric glands of the anuran Kassina maculata Dumeril were studied using the electron microscope. The cells of the oesophageal glands contained abundant secretory granules, rough endoplasmic reticulum and mitochondria. The cells of the gastric glands were composed entirely of chief cells which contained abundant mitochondria, few secretory granules and rough endoplasmic reticulum. It is likely that in K. maculata the oesophageal glands produce more pepsinogen than the gastric glands.     

体细胞克隆山羊"元元"肺的形态学观察

动物体细胞克隆是指由一个体细胞产生一个和亲代遗传基因一致、形态非常相像的动物。体细胞克隆已相继在牛、小鼠、山羊、猪、野牛、马、猫、大鼠等动物上取得成功。2000年6月中旬,西北农林科技大学生物工程研究所利用成年山羊耳部皮肤成纤维细胞作为核供体,获得两只体细胞克隆山羊——“元元”和“阳阳”。“元元”因呼吸衰竭仅存活36．05h。为了了解“元元”肺的发育情况,作者对“元元”的肺进行了肉眼、光镜和透射电镜观察。     

Pseudorabies virus infections in explants of porcine nasal mucosa.

The spread of infection and the morphogenesis of three pseudorabies virus strains were studied in explants of porcine nasal mucosa. Virulent NIA-3 virus was compared with a deletion mutant 2.4N3A, and with a non-virulent Bartha virus. All three virus strains infected nasal epithelial cells. NIA-3 virus particles were enveloped mainly at the inner nuclear membrane; the virus rapidly invaded the stroma, causing widespread necrosis. In contrast, 2.4N3A virus particles were enveloped mainly at the endoplasmic reticulum and the infection spread more slowly. Bartha virus particles were enveloped mainly at the endoplasmic reticulum; the infection spread slowly and remained restricted to the epithelial cells. In situ DNA hybridisation showed an accumulation of Bartha virus DNA in the nucleus 24 hours after inoculation. In nasal mucosa viral virulence seemed directly related to the speed of replication and release of virus from infected cells.     

Transpupillary diode laser retinopexy in dogs: ophthalmoscopic,fluorescein angiographic and histopathologic study

Objective To evaluate the ophthalmoscopic, fluorescein angiographic and light microscopic effects of diode laser retinopexy application in the tapetal and nontapetal fundus in the dog, and to ascertain appropriate laser power settings for production of photocoagulative lesions in these two regions. Animals studied Three adult female Beagle dogs. Procedures Laser burns were applied to selected areas in the fundus with an indirect headset delivery system using settings varying from 100 to 200 milliWatts (mW) and from 100 to 600 milliSeconds (mS) with total delivered energy ranging between 15 and 100 milliJoules (mJ). The dogs were then monitored by ophthalmoscopic examination and fluorescein angiography at regular intervals for 7–28 days. Histopathologic studies were performed at 7, 14 and 28 days after laser application. Results The diode laser produced ophthalmoscopically visible lesions in the nontapetal fundus with all laser settings used, and the appearance of these lesions corresponded to the energy levels used, and degree of pigment in the lased region. Gray‐white colored lesions with minimal subsensory retinal edema were seen with settings as low as 100 mWatts/150 mSeconds. In the tapetal fundus, laser burns were more difficult to produce, less repeatable, and required higher energy levels. Laser burns appeared as bronze, dark green or black discolorations of the tapetum with varying degrees of subsensory retinal edema. Lesions were more reproducible and were achieved with lower settings in the tapetal area of the tapetal/nontapetal junction. Ophthalmoscopically, depigmentation and repigmentation of the RPE (nontapetal fundus) and degenerative changes in the overlying retina (tapetal fundus) developed in the laser burns over the 28‐day study period. Fluorescein angiographic studies showed disruption of the blood–retinal barrier at the level of the RPE and fluorescein leakage into the subsensory retinal space was seen in most lesions at 24 h, was minimal at 3 days, and had resolved by 7 days. Histologically, grayish‐white lesions in the nontapetal fundus, and bronze to small black lesions in the tapetal fundus were typically characterized by outer retinal necrosis and RPE migration. Gliosis was considered minimal, was confined to the retina, and no inflammatory cells were seen. Peripheral intense white lesions (nontapetum) and lesions with a black center (tapetal fundus) were characterized by more extensive panretinal and choroidal necrosis. Most of the nontapetal lesions and a few in the tapetal fundus showed the formation of a central retinal detachment. Conclusions The diode laser effectively produces lesions suitable for retinopexy in both the nontapetal, pigmented fundus and the tapetal fundus, although variably so in the latter region. Initial laser settings of 100–150 mW/200 mS for the pigmented fundus, and 150 mW/200–300 mS for the peripheral tapetal fundus are recommended, and the clinician should gradually increase time interval settings to achieve a grayish‐white lesion in the nontapetum, and a bronze to slightly black lesion in the tapetal fundus. If possible, retinopexy should be applied to the peripheral tapetal area or tapetal/nontapetal junction.     

济宁青山羊松果体细胞超微结构的季节性变化

本试验旨在探讨松果体细胞与季节性繁殖的关系,为进一步揭示山羊季节性繁殖的内分泌机理提供参考。通过透射电镜观察济宁青山羊松果体细胞超微结构的季节性变化。结果表明:①松果体细胞可分为明细胞和暗细胞,在明细胞内滑面内质网(SER)的含量较粗面内质网(RER)丰富,而暗细胞内RER含量较丰富。另外明细胞内高尔基复合体和线粒体都较暗细胞内的复杂,但暗细胞内有较多的糖元颗粒。②夏季松果体细胞以暗细胞为主,明细胞较少,而春季明、暗细胞都较多。济宁青山羊松果体细胞的功能活动呈现季节性变化。     

Heritability of multifocal retinal dysplasia in American Cocker Spaniels

Multifocal retinal dysplasia was detected in 96 American Cocker Spaniels. Affected dogs were part of approximately 500 American Cocker Spaniels examined from 1972 to 1976 in statewide survey clinics for inherited cataracts and progressive retinal atrophy. The dysplastic retina was observable ophthalmoscopically in dogs as young as 3 to 4 weeks and as old as 7 years. Ophthalmoscopic features varied, depending on whether the dysplastic foci were in the tapetal or non-tapetal portion of the fundus. Over the tapetum, dysplastic foci appeared as multiple small irregularities of diminished and altered tapetal reflectivity. In the non-tapetal fundus, dysplasia appeared as areas of decreased pigmentation. Blindness or other apparent visual deficits were not observed in affected dogs. Histologic examination of affected eyes revealed focal dysplasia limited to the retina and optic nerve. Abnormalities included localized areas of retinal folding, rosettes, and retinal pigment epithelium hypertrophy and hyperplasia. Pedigree analysis demonstrated that 71 of the 96 affected dogs were related and could be identified in an extended pedigree. A recessive mode of inheritance was suggested, because in 5 litters (born to 10 affected parents), all 23 progeny that lived were affected. A dominant or polygenic mode of inheritance could not be ruled out.     

Ultrastructural Morphology of Plasma Cells in Normal Ovine Hemal Lymph Nodes

The fine structure of plasma cells from the hemal lymph nodes of five healthy sheep was examined. The plasma cells showed many cytoplasmic processes, indicating motility and phagocytic activity. They were randomly located in the medullary cords of the hemal lymph nodes. Their perinuclear spaces were irregular and contained granular material similar in density to that of rough endoplasmic reticulum. Some of the plasma cells provided morphological evidence of erythrophagocytosis at different levels. Such a phenomenon was previously reported only in pathological conditions. The red blood cell being engulfed by the plasma cell appeared smaller than normal. Most of the examined plasma cells showed Russell's Bodies inside the cisternae of the rough endoplasmic reticulum of the healthy hemal lymph nodes. Some of these Russell's Bodies had fuzzy borders. They were separated from the rough endoplasmic reticulum by evenly spaced halos.
Many plasma cells showed physical contacts with mast cells in the form of cell junctions, and some showed cytoplasmic continuity between the two cells. Such relations have been discussed in this article.