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Topic:Ultrastructure
Ultrastructure refers to the detailed architecture of biological cells as observed through electron microscopy. In horses, the study of cellular ultrastructure provides insights into the organization and function of various tissues and organs at a microscopic level. This includes the examination of cellular components such as mitochondria, endoplasmic reticulum, and lysosomes. Understanding the ultrastructure of equine cells aids in identifying cellular changes associated with disease processes, developmental stages, and physiological adaptations. This page compiles peer-reviewed research studies and scholarly articles that explore the ultrastructural characteristics of equine cells and tissues, contributing to a deeper understanding of equine biology and pathology.
Combined hepatocellular carcinoma and cholangiocarcinoma in a mare. A hepatic malignant tumour composed of both hepatocellular and cholangiocellular elements was studied histologically, immunohistochemically and electron microscopically in an 18-year-old Thoroughbred mare. Bile canaliculi and alpha-fetoprotein were useful in identifying the hepatocellular element, and mucin and keratin were good markers of biliary differentiation. The simultaneous presence of bile canaliculi and mucin-producing cells in most of the neoplastic lesions suggested that this tumour arose from a stem cell with capacity to differentiate into hepatocytes and biliary epithelium.
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 1. The occlusal surface and enamel thickness. Gross and microscopic examinations were undertaken on 46 cheek (molar and premolar) and 4 incisor equine teeth that were fractured, or sectioned either with a lathe or diamond saw. Specimens were examined without treatment, after decalcification or acid etching, utilising light, and scanning and transmission electron microscopy. In some horses, the occlusal surface of the teeth were covered with an organic pellicle. The occlusal surface of the underlying equine enamel contained different wear patterns, including polished areas, local fractures, wedge-shaped pits, striations and depressions. Oc...
Very high pressures are required to cause stress failure of pulmonary capillaries in thoroughbred racehorses. Thoroughbred horses develop extremely high pulmonary vascular pressures during galloping, all horses in training develop exercise-induced pulmonary hemorrhage, and we have shown that this is caused by stress failure of pulmonary capillaries. It is known that the capillary transmural pressure (Ptm) necessary for stress failure is higher in dogs than in rabbits. The present study was designed to determine this value in horses. The lungs from 15 Thoroughbred horses were perfused with autologous blood at Ptm values (midlung) of 25, 50, 75, 100 and 150 mmHg, and then perfusion fixed, and samples (d...
A light microscopic and ultrastructural examination of calcified dental tissues on horses: 4. Cement and the amelocemental junction. Ultrastructural examinations showed the diameter of cement lacunae to be greater in infundibular cement than in peripheral cement of upper cheek teeth, which in turn was greater than in the peripheral cement of the lower cheek teeth. However, numbers of lacunae/unit area remained similar in these 3 dentinal region. Two types of cemental hypoplasia were found in equine cheek teeth. The first type was termed central infundibular cemental hypoplasia and was confined to the central region of infundibular cement. The cement adjacent to these frequently large defects was very porous and contained la...
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 2. Ultrastructural enamel findings. Ultrastructural examinations of defined 3 equine enamel types termed equine (Eq.) Types 1, 2 and 3 enamel, according to the transverse appearance of their enamel prisms and the amount and appearance of their interprismatic enamel. Eq. Type 1 enamel contained alternating rows of oval shaped prisms and thick interprismatic enamel plates, and was found adjacent to the amelodentinal junction. Eq. Type 2 enamel consisted of circular, 'keyhole' to 'horseshoe' shaped prisms with little or no interprismatic enamel and was located adjacent to the amelocemental junction. Eq. Type 3 enamel was composed o...
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 3. Dentine. Ultrastructural examinations of equine dentine found that dentinal tubules extended from the amelodentinal junction towards the pulp forming primary curvatures. The number of dentinal tubules/unit area and their diameters increased significantly from the amelodentinal junction towards the pulp cavities, particularly in regular secondary dentine, but irregular secondary (tertiary) dentine contained no dentinal tubules. Dentinal tubules contained odontoblast processes that appeared to extend as far as the amelodentinal junction, but due to iatrogenic loss during specimen preparation, odontoblast...
Exercise-induced changes in the lung of Shetland ponies: ultrastructure and morphometry. The ultrastructural changes in pulmonary alveoli produced by running two ponies on a high speed treadmill at 7.6 m/sec, 3-degree incline, for 2 min support the hypothesis of pulmonary capillary stress failure as an explanation for exercise-induced pulmonary hemorrhage (EIPH). Light microscopy combined with scanning and transmission electron microscopy confirmed the presence of red blood cells and proteinaceous material in the alveolar lumina and interstitial swelling in approximately one third of the pulmonary alveoli examined. Morphometric analysis revealed that the blood-gas barrier was 30-7...
Equine synovial villi: distinctive structural organization of vasculature and novel nerve endings. The structural arrangement and cellular distribution of endothelial and lining cells of the synovial villi were studied in the equine palmar/plantar recess of the metacarpo- and metatarsophalangeal joints by light microscopy and electron microscopy. The extent and distribution of blood vessels varied with villous shape and length. The majority of vessels formed concentric circles in cross and longitudinal sections and probably are arranged in a convoluted, spiral or helical pattern. The villi do not contain smooth muscle cells or typical capillaries as observed in other organs. Under the elect...
[Observations of Setaria equina (Nematoda: Setariidae) with the optical microscope and scanning electron microscope]. Adults of S. equina (Spirurida, Setariidae), 1 male and 2 females, collected from vaginal sac of stallion, were studied by soanning electron microscopy (SEM). The amphids, cephalic and cervical papillae, peribuccal ring, fine transverse bands and bosses of the cuticle, as well as caudal papillae were visualized clearly at this examination. The results of the present survey contribute towards the identification of S. equina, improve the definition of the characters which are demonstrated by common light microscopy and give the exact number of male caudal papillae including the lateral cloacal r...
Cutaneous leishmaniasis in two horses. This report contains the clinical, histologic, immunohistochemical, and electron microscopic findings in two cases of equine cutaneous leishmaniasis. Nodular, sometimes crusty or ulcerated lesions were confined to the pinna and adjacent neck in both animals. The dermal inflammatory infiltrate was lymphohistiocytic in horse No. 1 and pyogranulomatous with formation of tuberculoid granulomas in horse No. 2. Numerous Leishmania organisms were found within macrophages in both animals. There was moderate to intense and specific reaction by immunoperoxidase using a polyclonal antiserum against Leish...
Nucleologenesis and ribonucleic acid synthesis in preimplantation equine embryos. The nucleolus is believed to be the active site of rRNA synthesis in all eukaryotic cells. In preimplantation embryos, the embryonic genome is apparently more or less silent up to a species-specific developmental stage at which a major burst of transcription occurs. Here we report on nucleologenesis and some ultrastructural aspects of the onset of RNA synthesis in equine embryos during in vivo development. The zygotes and embryos up to blastocyst stages were surgically recovered from normally cycling mares. Mares were induced to ovulate by treatment with 3000 IU hCG and inseminated 20 and 34 h...
Ultrastructure of equine morbillivirus. The ultrastructure of the equine morbillivirus (EMV) which was implicated in the death of one human and fourteen horses in Queensland, Australia during September 1994 and a 36 year old man from Queensland in October 1995 is described. The ultrastructure of the virus and the intracellular virus-specific structures are characteristic for the family Paramyxoviridae. Cytoplasmic nucleocapsids were observed within the infected cells monolayers, endothelial cells (lung) of infected horses and the neurons within the brain of the 36 year old Queensland man. Aggregates of smaller nucleocapsid-like stru...
Failure of endometrial cup development in the donkey-in-horse model of equine abortion. The mature preinvasive chorionic girdles of horse, mule, donkey and extraspecies donkey-in-horse conceptuses, and the very young endometrial cups on d 37 of gestation in mares carrying horse, mule and transferred donkey-in-horse conceptuses, were compared histologically and ultrastructurally to determine possible mechanisms underlying failure of endometrial cup development in the donkey-in-horse model of equine abortion. The progenitor chorionic girdle from the failing donkey-in-house pregnancy was similar in size to the normal donkey chorionic girdle but the trophoblast cells within the forme...
In vitro maturation and transmission electron microscopic observation of horse oocytes after vitrification. The study was designed to examine the suitability of immature horse oocytes for vitrification. Immature oocytes derived from slaughtered horse ovaries were transferred to a vitrification solution (EFS; 40% ethylene glycol, 18% Ficoll, and 0.3 M sucrose in modified phosphate-buffered saline) directly (Groups 1 and 4) or were first exposed to 20% ethylene glycol solution for 10 min (Groups 2 and 5) or 20 min (Groups 3 and 6). Oocytes were handled at 20 degrees C (Groups 1, 2, and 3) or 30 degrees C (Groups 4, 5, and 6). After vitrification and warming, their viability was assessed by maturation ...
Characterization of bone mineral crystals in horse radius by small-angle X-ray scattering. The size and the orientation of the bone salt (mineral) crystals in the cranial and caudal zones in the transverse midshaft section of the equine radius were investigated by small-angle X-ray scattering (SAXS). The results are interpreted as indicating that the crystals had an elongated shape with an average thickness of T = 3.17 +/- 0. 15 nm in the caudal region and T = 3.79 +/- 0.20 nm in the cranial region. Their orientation was predominantly in the longitudinal direction of the bone. There was no preferential orientation within the transverse plane. The distribution of tilt angles with res...
Use of semen as biopsy material for assessment of health status of the stallion reproductive tract. Conventional light microscopic evaluation does not fully utilize potential indicators in seminal ejaculates for diagnosis of disorders of the reproductive tract. The technique of evaluation of all cellular components of semen, as described in this article, utilizing both light and transmission electron microscopy is a valuable diagnostic tool. Compare with other common biopsy procedures, use of semen as biopsy material is noninvasive, more representative than excisional biopsy, less expensive, and helps in the longitudinal evaluation after a therapeutic regimen.
Repair and function of synovium after arthroscopic synovectomy of the dorsal compartment of the equine antebrachiocarpal joint. The reparative ability of equine synovium was determined by gross, histological, and ultrastructural examination. The functional potential of the synovium was estimated by examination of synovial cell organelles with transmission electron microscopy. Results from rested and exercised horses were compared to determine the effect of exercise on synovial healing. The response of synovectomized joint to exercise was evaluated with a standardized lameness examination and by gross, histological, and histochemical observations of the articular cartilage. A 7-mm diameter motorized synovial resector wa...
Equine papillary ependymoma. A 17-year-old Arabian gelding with progressive neurologic signs had a velvety, reddish brain tumor protruding from the ventral midline caudal to the optic chiasma. Histologically, the tumor had a papillary formation with a single layer of elongate cells radially oriented around a central fibrovascular core. Intracytoplasmic globular inclusions were positive for glial fibrillary acidic protein and weakly positive for vimentin. Ultrastructurally, these inclusions were comprised of whorling intermediate filaments. Neoplastic cells also had cytoplasmic interdigitations and numerous zona adherens a...
Cardiac rod body: hypertrophic Z-line in an aged pony. Numerous rod bodies were found in a heart sample from a 33-year-old pony by a conventional electron-microscopic technique. The rod bodies were concentrated in localized areas of both atria and ventricles, without a specific pattern of distribution. The rods appear to have a typical crystalline-like structure which presumably contains actin backbone filaments and alpha-actinin as major protein constituents. Diminution, fragmentation, and disorganization of the myofibrils, random expansion of electron-dense materials, especially at the fasciae adherens of the intercalated disc, an increase of in...
Collagen fibril diameter distributions in ligaments and tendons of the carpal region of the horse. Since horses bred for the racing industry are subject to rigorous training procedures there is a real need to understand how the stresses experienced by their tendons and ligaments in vivo relate to the major load-bearing elements-the collagen fibrils. Consequently, an age-related study has been made of the collagen fibril diameter distributions of nine ligaments in and around the equine carpus. This is the first stage of a larger study aimed at understanding the ultrastructural changes that occur as a result of exercise. Most of the ligaments showed a bimodal diameter distribution at maturity...
Segmented filamentous bacteria associated with lymphoid tissues in the ileum of horses. Segmented filamentous bacteria preferentially attached to the follicle-associated epithelium overlying the lymphoid tissue in samples of the terminal ileum from seven horses examined by scanning electron microscopy. The bacteria adhered to the apical membrane of the enterocytes by a holdfast segment. Each filament tended to be of uniform diameter, but the filaments ranged from 0.7 to 1.4 microns in diameter. The bacteria were usually absent from the adjacent villous epithelium.
Structural and endocrine aspects of equine oocyte maturation in vivo. The objectives were to describe the ultrastructure of equine oocytes aspirated from small and preovulatory follicles, and to relate the ultrastructural features to follicle size and follicular fluid steroid concentrations. Mares were examined every second day by transrectal ultrasonography, and follicles measuring > 30 mm were aspirated (in vivo) using a 20-cm-long 12-gauge needle through the flank. Following slaughter, both large and small follicles were aspirated (in vitro) from six mares. The oocytes were isolated under a stereomicroscope and processed for transmission electron microscop...
Ultrastructure of the secretory endometrium during oestrus in young maiden and foaled mares. Cyclical accumulation of uterine fluid occurs during oestrus and is often seen in excessive volumes in mares considered susceptible to endometritis. Since the mechanisms behind the formation of free uterine fluid remain to be clarified, the fine structure of the secretory equine endometrium was studied in biopsies collect during videoendoscopy from 14 endometritis-free, 4-9-year-old mares during oestrus. A distinct oedema of the tunica mucosa was evident. The surface epithelium had both ciliated and nonciliated cells and, particularly at the uterine body, often presented intra-epithelial macro...
Localisation of alkaline phosphatase in equine growth cartilage. The aim of this study was to localise alkaline phosphatase (ALP) activity in equine growth cartilage both histochemically and ultrastructurally. For histochemical studies, full thickness growth cartilage samples were obtained from 6 anatomical sites from 16 horses and ponies ranging in age from 90 d postconception to 12 years of age. For ultrastructural studies, samples were obtained from the lateral trochlear ridge of the distal femur of 3 animals ranging in age from 157 d postconception to 12 months of age. Alkaline phosphatase in histological sections was localised using a substituted napht...
Lymphoid tissues of the ileum in young horses: distribution, structure, and epithelium. Lymphoid tissues in the ileum of young horses form raised plaques that are macroscopically visible from the mucosal surface. These are termed "ileal lymphoid patches". These patches are variable in size, shape and position within the ileal wall, occasionally lying along the site of mesenteric attachment. Within lymphoid patches, follicles exist in three different morphological forms: follicle/dome structures, proprial follicles, and lymphoglandular complexes (LGCs). In follicle/dome structures, the majority of the follicle lies in the submucosa and merges with a dome in the lamina propria thro...
[Scanning electron microscopy of the synovial membrane of the distal phalangeal joint and the navicular bursa in horses]. 20 extremities of horses were used to investigate the synovial membrane of the distal interphalangeal joint and the navicular bursa. From each extremity five specimens were taken from the distal interphalangeal joint capsule, two further from the navicular bursa. Synovial villi were found near the articular cartilage as well as everywhere where the joint capsule did not form a tight periostal cover or was not connected with ligaments or tendons. Some lay between the articular surfaces of the phalanx media and phalanx distalis. Besides synovial villi and synovial folds "trabecular-like" cords o...
A scanning electron-microscopic analysis of the morphology of equine lower lip sinus hair. Sinus hairs, which are tactile organs of most mammals, are differentiated into cavernous and sinus types. The horse has the cavernous type. Horse lower lips were perfused in diluted Karnovsky's fixative and sinus hair processed for scanning electron microscopy. Anastomosing trabeculae of different thickness and shape originate from the internal connective tissue layer and extend to the external layer, thus forming a dense meshwork suspending the hair root like a net. However, many of the distal trabeculae do not reach the external wall of the blood sinus but end in a finger-like knob within th...
Spermatophagy in the stallion epididymis: a scanning and transmission electron microscopy study. The occurrence of phagocytosis of spermatozoa in the epididymis is a controversial issue in male reproductive biology. In this paper we documented, by scanning and electron microscopy, the presence of spermatophages in the lumen of the proximal region of stallion epididymis. Sperm phagocytosis involving the principal cells that line the cauda epididymidis region was also observed. The possible meaning of this process in the removal of damaged, aged or surplus spermatozoa is discussed. These observations were made in samples obtained from random cases, during the course of research work carried...
The pineal body of the mink and horse with special reference to the reproductive cycle. An ultrastructural and immunocytochemical study. An ultrastructural and immunohistochemical analysis was performed on the epiphysis of two species of mammals: mink and horse. These animals present a reproductive cycle that varies along the year according to the light exposition. The aim of the study was to define possible structural changes connected with the gonadal activity. Structural aspects in common emerged such as those in concern with the epiphysis cells, their immunocytochemical characteristics (NSE and Synaptophysin positivity of pinealocytes, as well as CFAP positivity of further cells), and those in concern with the general ultra...
Stress failure of pulmonary capillaries as a limiting factor for maximal exercise. The pulmonary blood-gas barrier has a basic physiological dilemma. On the one hand it needs to be extremely thin for efficient gas exchange. On the other hand it also needs to be immensely strong because the stresses on the pulmonary capillary wall become extremely high when the capillary pressure rises on exercise. Maximal hydrostatic pressures in human pulmonary capillaries during exercise are not accurately known but must exceed 30 mmHg. In some animals, for example thoroughbred horses, the capillary pressure rises to about 100 mmHg. These pressures cause stresses in the capillary wall of 5...
