A light and electron microscopic and immunohistochemical study of human arachnoid villi

The structure of human arachnoid villi was investigated by light and electron microscopy with the aid of immunohistochemical techniques. The human arachnoid villi examined were basically composed of four portions: a fibrous capsule, an arachnoid cell layer, a cap cell cluster, and a central core. The arachnoid cell layer encompassing the central core was mostly covered by the thin fibrous capsule with an endothelial investment. However, the fibrous capsule was often absent at the apical portion of the villus and a factor VIII-related antigen stain failed to confirm the investment of endothelial cells. Instead, the arachnoid cell layer abutted directly upon the lumen of a lateral lacuna or the sinus. The arachnoid cell layer was thickened in places, forming cap cell clusters; it usually consisted of outer and inner zones. On vimentin staining, the former was slightly positive while the latter was strongly positive. The central core contained a network of arachnoid cells intermingled with connective tissue fibers and was in continuity with the cranial subarachnoid space. Electron microscopy showed that the arachnoid cells contained a larger number of intermediate filaments in the inner zone than the outer zone. Ultrastructural immunohistochemical localization showed that vimentin was localized at the intermediate filaments and desmosomal plaques of the arachnoid cells. The arachnoid cells showed a marked variety in both the cell forms and the number of intermediate filaments or desmosomes, depending on their location.     

Morphological alterations in tryptic esophagitis: an experimental light microscopic and scanning and transmission electron microscopic study in rabbits

The morphology of esophageal mucosal damage induced by trypsin was investigated in an experimental model, where the rabbit esophagus was perfused in situ with a control solution (physiologic NaCl) and trypsin (1 mg/ml). The results indicate that trypsin has an adverse effect on esophageal mucosa. In light microscopy infiltration of leucocytes in the submucosa and later ulcerative changes in the mucosa were seen. Scanning electron microscopy showed detachment of superficial cells and later deeper lesions, displaying denuted intramucosal collagen bundles with erythrocytes. In transmission electron microscopy significant widening of the intercellular spaces could be seen. This suggests that in clinical situations trypsin refluxed from duodenum into stomach and further to esophagus has an adverse effect on esophageal mucosa and may have importance in the pathogenesis of clinical reflux esophagitis. Because of the relatively high pH-optimum trypsin may have importance only under nonacidic or alkaline conditions.     

Polyglycolic acid suture in the urinary tract. A light and electron microscopic study

Cystotomies in 100 guinea pigs were closed with polyglycolic acid suture. Light and electron microscopic studies of wound areas showed a transitory acute inflammation, attributable to the trauma of insertion, followed by invasion of the suture braid by multinucleated giant cells. The notching and transection of braid fibers by these giant cells probably is responsible for the early loss of tensile strength reported for this suture.     

Mixed colloid cyst-xanthogranuloma of the third ventricle. A light and electron microscopic study

A mixed colloid cyst-xanthogranuloma of the third ventricle is described. The xanthogranuloma associated with the cyst completely occupied the third ventricle. On light microscopy, a single epithelial layer with a basal lamina was seen lining the cyst wall. Electron microscopic study revealed three different kinds of cells in the epithelial layer: ciliated, nonciliated, and basal cells. Many lipid droplets were present in the superficial epithelial cells, macrophages, pericytes, and endothelia. The pathogeneses of the cyst and of the xanthogranuloma are discussed.     

A light and electron microscopic study of oedematous human cerebral cortex in two patients with post-traumatic seizures

Primary objective : Brain cortical biopsies of two patients with clinical diagnosis of complicated brain trauma who had seizures, were studied by means of light and electron microscopes in order to correlate structural alterations with seizure activity.

Methods and procedures : Biopsy samples of left frontal cortex and right parietal cortex were processed by current techniques for light and transmission electron microscopy.

Results : The tissue showed severe vasogenic oedema with perivascular and intraparenchymatous haemorrhages. At the capillary wall, increased vesicular and vacuolar transendothelial transport, open endothelial junctions, thickened basement membrane and swollen perivascular astrocytic end-feet were observed. Some pyramidal and non-pyramidal nerve cells appeared dense and shrunken and others exhibited marked intraneuronal enlargement of membrane compartment. The myelinated axons displayed signs of degeneration and a process of axonal sprouting. Numerous swollen asymmetrical axo-dendritic synaptic contacts were observed in the neuropil, which exhibited mostly closely aggregated spheroidal synaptic vesicles toward the presynaptic membrane and numerous exocytotic vesicles sites. The perisynaptic astrocytic ensheathment appeared retracted or absent, whereas the extracellular space appeared notably dilated. Synaptic disassembly was also observed.

Conclusion : The findings demonstrate, in two patients with post-traumatic seizure activity, brain brarrier dysfunction, vasogenic oedema, anoxic-ischaemic neurons, axonal sprouting, numerous altered excitatory synapses and synaptic disassembly. Some considerations on clinical and research applications are discussed.     

A light and scanning electron microscopic study of osteocyte activity in calcium-deficient rats

Summary The material herein is an extension of an earlier study of osteocyte lacunae in calcium-deficient rats, utilizing morphometric measurements in undecalcified bone sections and scanning electron microscopy. The results confirm our earlier finding that bone resorption resulting from a low-calcium diet is not accompanied by osteocytic resorption.     

Cysts of the semilunar cartilage of the knee. A light and electron microscopic study.

The semilunar cartilages of the knee of six cases showing various degrees of mucoid degeneration with cyst formation were studied with the light microscope. Three cases were selected for electron microscopic observation which revealed that some of the cystic spaces filled with mucoid material were lined by synovial cells. Masses of mucinous, alcian bluc positive material (acid mucopolysaccharides) were observed also among degenerated and intact bundles of collagen. It is concluded that the accumulation of acid mucopolysaccharides in meniscial cysts is at least in part a product of secretion of synovial cells. This observation explains the high incidence of recurrence of meniscial cysts after incomplete surgical excision and supports the concept that it is an active rather than a degenerative process.     

Primary pigmented nodular adrenocortical disease. A light and electron microscopic study of eight cases

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of Cushing's syndrome, which is adrenocorticotropic hormone-independent and involves both adrenal glands. The characteristic pathological features include multiple pigmented cortical nodules and atrophy of the internodular cortex. The adrenal size ranges from small to normal or slightly enlarged. Review of the gross, light microscopic, and ultrastructural features of eight cases seen at the National Institutes of Health revealed several very unusual findings. We observed the following in our patients: macronodules up to 3.0 cm; microscopic foci of necrosis; mitoses; cortical hyperplasia rather than internodular atrophy; focal confluence of nodules giving a diffuse pattern of cortical involvement, and a focal trabecular growth pattern. The nodules were composed primarily of eosinophilic, lipid-poor cells similar to those of the zona reticularis. However, lipid-rich cells similar to those of the zona fasciculata were also demonstrated in the nodules by both light and electron microscopy. This suggests that the adrenal cortical nodules of PPNAD may be derived from not only the zona reticularis, but also the zona fasciculata.     

Rhinitis medicamentosa: electron microscopic changes of human nasal mucosa.

OBJECTIVE: Prolonged application of nasal vasoconstrictors causes rhinitis medicamentosa (RM). Nasal obstruction is induced by rebound swelling when the decongestive effect has disappeared. The aim of this study was to demonstrate ultrastructural changes in RM. STUDY DESIGN AND SETTING: Tissue samples of inferior turbinates from 22 patients with RM and 10 patients without rhinitis were taken during nasal surgery. Ultrathin sections were investigated by using a transmission electron microscope (TEM). RESULTS: The TEM findings revealed severe epithelial damages such as loss of ciliated cells. In the subepithelial region, the vascular endothelium showed gaps and ruptures of basal lamina. CONCLUSION: RM is a drug-induced damage of human nasal mucosa. Loss and destruction of ciliated epithelial cells are the morphologic correlation of the disturbed mucociliary clearance. In addition, vascular endothelium revealed ultrastructural changes. This could be caused by an increased vascular permeability with consecutive interstitial edema. SIGNIFICANCE: This study demonstrated new morphological aspects of rhinitis medicamentosa.     

The effect of sensory denervation on rabbits' knee joints. A light and electron microscopic study.

Unilateral sensory denervation of the hind limb in a group of rabbits caused progressive atrophy of cells in all structures of the knee joint, whether or not the joint was protected by a plaster cast. Immobilization without denervation caused proliferative changes, first in the synovium and then in the articular cartilage. The initial changes in the articular cartilage following sensory denervation occurred in the middle layers, suggesting that nutritional deficiency was involved. In contrast, the first changes in the cartilage of intact immobilized limbs occurred in the superficial layers and were most likely of mechanical origin.     

Mineralization in osteoblast cultures: a light and electron microscopic study

Osteoblasts isolated mechanically from newborn mouse calvaria produced a calcified matrix when cultured in the presence of 10 mM beta-glycerophosphate or 3 mM inorganic phosphate. The uncalcified matrix revealed numerous matrix vesicles scattered among collagen fibrils. The calcified matrix showed mineralized collagen fibrils and calcified nodules whose underlying organic matrix was detected after decalcification. These structures resembled those described in fetal and woven bone. In partially decalcified areas, calcification was shown to spread out from these structures along collagen fibrils. Alkaline phosphatase activity was found associated with the plasma membrane and matrix vesicles. X-ray diffraction analysis demonstrated that the mineral phase deposited in culture was hydroxyapatite. These observations which demonstrate that the isolated cells elaborate in culture a mineralized matrix with chemical and ultrastructural properties of woven bone further support the osteoblastic nature of the cells.     

Effects of hydrocortisone on the vertebral cartilage plate in mice. A light and electron microscopic study

Together with other side effects, the clinical use of steroid appears to produce disorders in the spinal column, especially in young patients. However, morphologic details of steroid induced changes in the spinal column are little known. In this study, mice were treated with daily intramuscular injections of hydrocortisone at doses of 1, 5, and 10 mg/kg body weight for 1, 2, or 4 weeks after 2 weeks of age, and the cartilage plates of the lumbar vertebrae were examined, compared with controls, by light and electron microscopy. Cartilage plates consist of an outer zone, abutting the nucleus pulposus and an inner zone oriented toward the vertebral body. The outer zone is divided into a superficial layer and a deep calcified layer. With steroid therapy, chondrocytes in the inner zone and the superficial layer of the outer zone became degenerative or necrotic. In mice treated with 5 and 10 mg hydrocortisone/kg body weight, ossification appeared earlier in the deep calcified layer than in control animals. After 2 weeks of treatment, the cartilage tissue of the inner zone in mice treated with 10 mg hydrocortisone contained ossification gaps, columnar bone tissue, connecting the bony vertebral body, and the deep calcified layer of the outer zone. The thickness of each layer was measured by light microscopy. By hydrocortisone treatment, the whole of the cartilage plate decreased in thickness, the two cartilage layers of the inner zone and the superficial layer of the outer zone became thinner, and the calcified or ossified layer of the outer zone became widened.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oligodendroglial cell behaviour in traumatic oedematous human cerebral cortex: a light and electron microscopic study

Cortical biopsies of 12 patients with traumatic brain injuries have been used in the present study to examine oligodendroglial cell changes and reactivity. The samples were processed for light and transmission electron microscopy. Four main types of oligodendrocyte populations have been found: resting or unreactive oligodendrocytes, reactive oligodendrocytes, anoxic-ischaemic oligodendroglial cells and hyperthrophic phagocytic oligodendrocytes. The unreactive or resting oligodendrocyte type exhibited a fusiform or elongated shape, a clear or dense band of scarce perikaryal cytoplasm and a nucleus with peripheral heterorocromatin masses. Clear or dense reactive oligodendrocytes showed increased amount of perikaryal citoplasm, dilated endoplasmic reticulum and nuclear envelope, numerous clear, oedematous mitochondria and dense bodies. These oligodendrocytes appeared associated with degenerated myelinated axons. Anoxic-ischaemic oligodendrocytes showed lacunar enlargement of endoplasmic reticulum, dilated Golgi complex and enlargement and disassembly of nuclear envelope. They appeared also in contact with degenerated myelinated axons. Hypertrophic phagocytic oligodendrocytes were observed engulfing the associated degenerated myelinated axons, invading the myelin sheath, separating the myelin lamellae and exerting myelinolitic effects. Oligodendroglialpseudopodic expansions were observed phagocyting the axoplasmic matrix and leaving a huge vacuolar axoplasmic space. The vasogenic and cytotoxic components of traumatic brain oedema are discussed in relation with the oligodendroglial cell changes and reactivity.     

Epithelial cells in a so-called intraspinal neurenteric cyst: A light and electron microscopic study

A case of so-called intraspinal neurenteric cyst is described. A single epithelial cyst, associated with a dimple in the sacral region, was located ventral to the spinal cord in the lower cervical region. On light microscopy, a single epithelial layer lining the cyst wall contained a few ciliated cells and squamous cells, in addition to many goblet cells. An electron microscopic study also demonstrated three different kind of cells. The goblet cells contained many secretory granules, the ciliated cells had many cilia, and the squamous cells were characterized by abundant tonofilaments and desmosomes.     

Calcitonin gene related peptide immunoreactivity in rat lung: light and electron microscopic study.

Calcitonin gene related peptide immunoreactivity was investigated in the rat lung. Immunoreactive material was observed in nerve fibres surrounding bronchi, bronchioli, and blood vessels, and also in neuroendocrine cells and neuroepithelial bodies. In addition, the peptide was identified by immunoelectron microscopy in dense cored vesicles of granulated cells of the neuroepithelial bodies. These observations suggest that calcitonin gene related peptide plays a part in the regulatory function of the rat respiratory tract, exerting its influence by endocrine, paracrine, neurosecretory pathways, or a combination of these.     

Malignant paraganglioma of retroperitoneum light, electron microscopic and ultrasonographic study

A malignant retroperitoneal nonchromaffin paraganglioma in a thirty-four-year-old man was studied by light and electron microscopy. Histologically, the tumor cells displayed a tendency to surround granular, eosinophilic intercellular material and to form nests and pseudoacini. Ultrastructurally, the tumor was composed of moderately well-differentiated epithelial cells intermixed with sparse sustentacular cells. An organoid pattern, reminiscent of the functional anatomic unit of nonchromaffin paraganglia, was seen occasionally. Epithelial cells formed pseudoacini around dilated interstitial spaces and rosettes around cytoplasmic masses composed of interdigitating microvillous processes. These morphologic features are consistent with the neurocrestal origin of paragangliomas. The patient died ten months after presentation despite an initial favorable response to irradiation.