Histological Zones Research Articles

Effects of rapid pulsed CO2 laser beam on cortical bone in vivo.

Twenty rabbit femurs were used to study the effect of CO2 laser on cortical bone. Sixteen femurs were treated with 20 watts, 3 mm defocused beam, 2 KHZ spike pulse mode CO2 laser for 10 seconds through a circular window in the metaphysis. In four control femurs, the inner cortex was exposed without laser treatment. The animals were killed at 4 and 6 weeks and the specimens studied histologically. All laser-treated specimens showed thermal changes. Three histological zones were observed. A superficial zone of inner cortex close to the beam consisted mainly of carbonization or carbon ash during resorption. An intermediate zone consisted of bone necrosis and healing with associated areas of new bone formation. The deep zone of outer cortex had normal bone with no cellular damage. No such changes were observed in the control specimens. The CO2 laser can be used to generate a controlled zone of tissue ablation, which may make it a potentially useful tool for tumor margin cauterization.

Articular cartilage: correlation of histologic zones with signal intensity at MR imaging.

Zones of high and low signal intensity on magnetic resonance (MR) images of articular cartilage were correlated with the four histologic zones normally found in such cartilage. Grossly normal articular cartilage from knees and ankles of a fresh cadaver were used in the study. The three zones identified on MR images included a low-intensity zone near the articular surface, a zone of higher signal intensity next to that, and a second zone of low intensity that was deep to the two others. The location of the superficial low-intensity zone corresponded to dense, tangentially oriented layers of collagen in the superficial histologic zone. Higher signal intensity deep to the superficial low-intensity zone correlated with cartilage in the transitional zone. The deep low-intensity zone correlated with a combination of deep radiate and calcified cartilage and cortical bone. Results of this study indicate that, with high resolution, MR imaging may demonstrate three zones of differing signal intensity in articular cartilage. The superficial low-intensity zone may be a useful marker of the surface of normal articular cartilage.

Relationship between Clinical Stage and Histological Zone of Origin in Early Prostate Cancer: Morphometric Analysis

A detailed morphometric analysis of 96 radical prostatectomy specimens (13 clinical stage A1, 29 A2, 34 B1 and 20 B2) was undertaken to examine the relationship of zone of origin to volume, grade and extraprostatic extension of cancer. In patients with stage A disease, transition zone (TZ) cancer (present in 81%) was significantly larger but of lower grade than peripheral zone (PZ) cancer (present in 90%). The total volume of cancer in stage A1 patients averaged 1.55 ml with 72% of TZ origin. In patients with stage A2 disease, tumour volume averaged 5.83 ml with only 57% of TZ origin. Specimens taken during transurethral resection of the prostate (TURP) revealed TZ cancer in 82% and PZ cancer either alone or with TZ cancer in 22%. The 9 patients with PZ cancer in the TURP specimen included 5 of the 11 with extracapsular extension and all 5 of those with seminal vesicle invasion. Every patient with stage B disease had PZ cancer which, in all except 3 cases, was of significantly larger volume and higher grade than any TZ cancer (present in 43%) in the same gland. In patients with stage B cancer, total tumour volume was 5.13 ml with 91% of PZ origin. TZ cancer tended to be well differentiated in all patients, even at large volumes, whereas PZ cancer was often moderately or poorly differentiated even at low volumes. In patients with stage B disease, TZ cancer appeared to be incidental and of no clinical importance, while in stage A patients PZ cancers were sometimes large, poorly differentiated and extended outside the prostate. Progression of a stage A cancer seems more likely to result from PZ cancer than TZ cancer, and the finding of PZ cancer in a TURP specimen should probably preclude its classification as stage A1.

Effects of CO2 laser beam on cortical bone

Sixteen bone blocks from two freshly amputated legs were used to study the effect of CO2 laser on cortical bone. They were divided into two groups. In Group I, the blocks were treated with CO2 laser using 1 mm spot (focused mode). In Group II, they were treated with CO2 laser using 3 mm spot (defocused mode). Two other variables were investigated: the power and time of exposure. Three histologic zones were observed: a superficial zone with black particle deposits (carbonization), an intermediate zone with fibrillations and enlarged empty lacunae, and a deep zone with normal appearing bone. The bony changes in the first two zones combined were superficial in all specimens and did not exceed 200 microns. Increased energy, a focused beam, and time of exposure were all associated with increased matrix changes. CO2 laser can be applied to cortical bone in vitro with minimal residual thermal damage.

Histology of the anal canal.

The normal gross and microscopic morphology of the anal canal is described, including the more common variants. Constant problems in the literature are the confusing terminology and the relation of the histological zones to the so-called cloacal membrane. For this reason, the review includes remarks on the history, embryology, and nomenclature.

Pseudomalignant myositis ossificans occurring in the hand

This is a case report of a patient with pseudomalignant myositis ossificans of the hand. This entity is usually related to trauma, but there was no history of injury in this patient. Radiographic follow-up, histologic zone phenomena and computerized tomography are helpful in obtaining the correct diagnosis.

Traumatic myositis ossificans in masticatory muscles

3 cases of traumatic myositis ossificans circumscripta, located within the masticatory muscles are presented. Two of the lesions involved the masseter muscle, and exceptionally, 1 involved the temporalis muscle. Three pathognomonic histological zones, permitting the differential diagnosis of myositis ossificans from sarcomatous lesions, are described, and treatment incorporating ideally early surgical intervention with wide excisional biopsy of the lesion is stressed.

Natural root caries: a histologic and microradiographic evaluation

The purpose of this study was to obtain information about the detailed histopathology of naturally occurring root caries. Fifty extracted human teeth exhibiting some degree of root caries were sectioned longitudinally and examined with transmitted light, polarized light and microradiography. The occurrence of the histological zones of dentinal caries was tabulated and revealed a lesion body in all cases. Light microscopy showed the same basic features as microradiography and was most useful when the sections were imbibed in quinoline. A structureless area below the main body of the lesion was observed in 77% of the cases when using quinoline. This fluid more clearly defined the extent of the lesion and may show a "phenolic reaction" when using polarized light microscopy. Partial radiopaque surface layers were observed in almost 80% of the sections. This study has described the detailed histopathology of root caries, and aids in the development of model systems to evaluate this emerging dental health problem.

CELL CYCLE DURATION IN THE MERISTEM OF NEPHROLEPIS BISERRATA STOLONS: THE ROLE OF THE APICAL CELL

The stolons of Nephrolepis biserrata (sw.) Schott are thin axes that grow rapidly (from 2 to 4 mm per day) in the controlled conditions applied. In the cylindro‐conical meristem, three histological zones are defined. Cell cycle duration was determined for each zone by autoradiographic methods after incorporation of tritiated thymidine and confirmed by the colchicine‐induced metaphase‐accumulation technique. The apical cell and its derivatives (Zone 1) are mitotically more active (cell cycle duration: 80 hr) than the cells of the subapical zones (2 and 3), where cell cycle lengths are 142 hr and 95 hr respectively. These data, compared to previous results, give evidence for the main role played by the relative rate of division of the apical cell compared to that of lateral cells in the organization and the shape of the meristem of pteridophytes. Moreover, the apical cell appears to be unique in having a differentiated cytological aspect not usually associated with an intensely proliferating cell.

Immunohistochemical studies on the localization of cellular retinol-binding protein in rat testis and epididymis.

The immunohistochemical localization of cellular retinol-binding protein (CRBP) was studied in rat testis and epididymis. Parallel studies were also carried out on the localization of plasma retinol-binding protein (RBP) and transthyretin (TTR) in testis. The studies employed antibodies purified by immunosorbent affinity chromatography, permitting the specific staining and localization of each antigen by the unlabeled peroxidase-antiperoxidase method. For RBP and TTR, specific immune staining was found in the interstitial spaces between the seminiferous tubules, and not in the tubules themselves. In contrast, strong specific immune staining for CRBP was found in the seminiferous tubules, with a striking localization within Sertoli cells. Moreover, a distinct cyclic variation of specific staining for CRBP within Sertoli cells was observed during the spermatogenic cycle. This cyclic variation was seen with regard to both the intensity of staining and to the anatomic distribution of CRBP within the Sertoli cells. Within the epididymis CRBP was selectively localized to the proximal portion of the caput epididymidis, with variations in intensity of the staining of the epithelium of the ducts in different histological zones. Specific immune staining for CRBP was very weak or absent in the other portions of the epididymis. These results were confirmed by radioimmunoassay. Vitamin A-deficient rats showed markedly reduced specific immune staining for CRBP in both testes and epididymides, and greatly reduced levels of CRBP in these tissues on radioimmunoassay. These studies on the localization of CRBP provide information concerning the specific cells and anatomic loci within the testis and epididymis where retinol may be playing an important role in sperm formation and maturation.

Ulfrastructure of the histological zones in growing vegetative buds of Salix spp.

Ultrastructural differentiation in the shoot apex of growing vegetative buds of Salix was studied, and some micrographs analysed morphometrically. The distribution of inorganic phospahte (P;) was analysed cytochemically. A distinct histological zona–tion was observed in the apex. The relative volumes of nuclei and plastids were significantly higher in the central tunica zone than in the peripheral one. The corpus differed from the central tunica zone by significantly lower volume density of nuclei and higher of vacuoles and mitochondria. During differentiation of the rib meristem vacuole volume increased significantly, while the relative volumes of nuclei, mitochondria, nucleoli, and heterochromatin decreased. It was not possible to decide whether the vacuoles originate from ER or GERL. Morphogenesis of chloroplasts with large starch grains and grana from proplastids was evident in the rib meristem; dedifferentiation to S–plastids was found in the protophloem. Prolamellar bodies were observed in the procambium plastids. The protophloem was characterized by P–protein and spiny vesicles. Pi was found in the nucleoli of most epidermis cells, several procambium cells, and a few chlorencyma cells, but never in the tunica of the growing apical and developing lateral buds. Pi also occurred in some plasmalemma–somes and occasionally in the walls in connection with plasmodesmata.

The internal morphology of surface zones from acid-etched caries-like lesions of enamel: An SEM study

The typical carious lesion of enamel is composed of four distinct histologic zones: 1) the surface zone (SZ), 2) body of the lesion (BL), 3) the dark zone and 4) the translucent zone. This study concerned only the SZ, the most superficial zone of enamel caries. Both the SZ and BL may be viewed when a carious lesion is imbibed in water and examined in polarized light (PL). The SZ has a pore volume of less than 5%; whereas the BL has a pore volume of at least 5%, representing the area of the lesion with the greatest mineral loss. Previous SEM studies have shown few differences between the morphologic characteristics of SZs and sound enamel. Remineralization of enamel caries is possible in vitro, but requires repeated, long exposures to calcifying fluids due to the intact SZ. If the intact SZ could be made slightly porous while maintaining its integrity, remineralization of the underlying BL could be facilitated.

Morphologie, structure et ontogénie des nectaires floraux de l’Ailanthus glandulosa

Staminate and hermaphroditic flowers show an hypogynous disc which is composed of two separate parts, an apical and a basal part. These histologic zones should be considered as nectaries. They differ by their position, their shape, and the content and state of differentiation of their cells. Basal nectaries are not vascularized but phloem bundles reach the tip of the disc. Initiation of nectariferous tissue occurs after that of the floral parts. The basal nectaries appear first but the number of cells still increases during the formation of the apical part of the disc. Both basal and apical nectaries have a superficial origin. Numerous anomocytic stomata are present especially on the surface of the apical nectaries; they are rounded and keep their stomatal pores open. On basal nectaries, however, they occur much less frequently.

The effect of fluoride in the remineralization of enamel caries and caries-like lesions in vitro.

Remineralization occurs naturally during the formation of a carious lesion in human dental enamel and is seen in the form of two of the four classical histological zones of the lesion. Exposure of small lesions to a synthetic calcifying in vitro results in a significant increase in remineralization of the lesion. The degree of remineralization achieved depends upon the presence of fluoride ions in the calcifying fluid and its degree of supersaturation. It appears that only low levels of fluoride are required to trigger the mechanism of remineralization; raising the fluoride level further does not result in a greater degree of remineralization. The calcium ion concentration of the calcifying fluid is critical with respect to determining which components are supersaturated and which in turn determines the degree of remineralization achieved. With levels of 3.0 mM calcium only the superficial region of the lesion is remineralized whereas with a calcium concentration of 1.0 mM, remineralization occurs in depth. It is hoped that studies on remineralization phenomena will provide further insight into the mechanisms of caries formation and be the basis for a more powerful and effective form of caries prevention.

Neuropathological and computerized tomographic findings in experimental brain abscess.

The neuropathological progression of brain abscess formation was studied experimentally at sequential stages in dogs, and the findings correlated with the appearance on computerized tomographic (CT) brain scans. The evolution of brain-abscess formation was divided into four stages based on histological criteria: early cerebritis (Days 1 to 3); late cerebritis (Days 4 to 9); early capsule (Days 10 to 13); and late capsule (Days 14 and later). The cerebritis stage was characterized by prominent perivascular cuffing by inflammatory cells in the area adjacent to the developing necrotic center. However, the early elements of capsule formation appeared with the presence of fibroblasts by Day 5. The CT scans showed ring-shaped contrast enhancement by Day 3. Delayed scans at 30 minutes revealed diffusion of the contrast material into the developing necrotic center, forming a solid lesion. In lesions that were well encapsulated (14 days and older), five distinct histological zones were apparent: 1) a well formed necrotic center; 2) a peripheral zone of inflammatory cells, macrophages, and fibroblasts; 3) the dense collagenous capsule; 4) a layer of neovascularity associated with continuing cerebritis; and 5) reactive astrocytes, gliosis, and cerebral edema external to the capsule. The CT appearance of well encapsulated abscesses showed a typical ring-shaped contrast-enhancing lesion. On the delayed scans, the "ring" did not fill in with contrast enhancement. The diameter of the ring correlated best with the presence of cerebritis (perivascular infiltrates in the adventitial sheaths of vessels surrounding the abscess). The discussion focuses on the relevance of this study to the current management of patients with brain abscess.

Quantitative Study of RNA in the Shoot Apex of Pteris cretica during its Development

Summary A quantitative study of RNA metabolism is carried out during the development of the meristem of Pteris cretica L. by means of microspectrophotometric and histoautoradiographic methods after the determination for each histological zone, of the average cellular, nuclear, vacuolar surfaces and volumes and of the free cytoplasm volume. The apical cell is throughout the growth the cell containing the greatest amount of RNA and where the synthesis rate is the highest. But, per free cytoplasm unit, the highest RNA concentration and synthesis rate are found in the cells of the lateral zone. The RNA turn over speed which is identical in the different apical zones, decreases as the plant develops. RNA metabolism is intense in the adult apical cell which is differentiated and has a very slow cellular cycle. This fact constitutes an argument in favour of the adult apical cell playing important role in the general functioning of the meristem.

Quantitative Histochemical Study of a Vitamin E Analog on Rat Gastric Cyclic AMP

The vitamin E analog, 2,2,7,8-tetramethyl-5,6-orthoquinonechroman, unlike vitamin E itself, had been reported to be a potent inhibitor of beef liver cyclic AMP-PDE in vitro (about 3.5 times more inhibitory than theophylline under the same conditions). In this in vivo study, single intraperitoneal injections were given to fasted rats, 15 min before killing, of a solution of 20, and of a suspension of 130, mg analog/kg in 4% ethanol. No significant increases over the 4% ethanol control values in cyclic AMP levels were produced in any of the histological regions of the glandular stomach. However, injection of the 4% ethanol itself produced a rise of about 50% (peak value 4.1 pmoles/mg wet wt, 0.16 pmoles/mug protein-nitrogen) in the cyclic AMP concentrations in the parietal cell region and had no significant effect in any of the other histological zones where the concentrations were much lower.

Chemical Studies on the Human Growth Cartilage in Fetuses and Newborns

Microchemical determination of hexosamine and hydroxyproline performed in isolated histological zones from sections of tibial epiphyseal plate obtained from fetuses, newborn infants and children showed a decrease of hexosamine and an increase of hydroxyproline concentration with age. Fractionation of glycosaminoglycans demonstrates that the differences in hexosamine are due mainly to variations in chondroitin sulphates. Gel electrophoresis of protoeglycans showed different patterns in fetuses and in older children. It is suggested that the permeability, sieving and ionexchange properties of the growth plate change probably with age. In several newborns with important general pathologic findings, a decrease of hexosamine was found in the column zone.

Microchemical analysis of human tibial growth cartilage in various forms of dwarfism.

ABSTRACT Microchemical determinations of glycosaminoglycans and collagen were preformed in isolated histological zones from sections of tibial epiphyseal plate biopsies obtained from children with growth disorders (pituitary dwarfism, congenital myxoedema, Turner's syndrome, Noonan's syndrome, mucopolysaccharidosis type VI, vitamin D resistant rickets and achondroplasia). Alternate sections were used for histochemical localization of glycosaminoglycans and proteins. The values were compared with those found in comparable zones of the growth plate from normal children of the same age. The chondroitin sulphate concentration (% of defatted dry wt.) in the normal epiphyseal plate increased from the resting zone towards the proliferating/hypertrophic zone; collagen exhibited a reverse trend. In some of the pathological biopsies the concentration of chondroitin sulphate was slightly decreased whereas that of collagen was slightly increased. A marked increase in the collagen concentration was found in achondroplasia. The solubility profiles of the cetylpyridinium complexes of the chondroitin sulphate fraction showed three main peaks with slight but characteristic differences in the various zones of the normal cartilage plate. Significant shifts in the proportion of these peaks were observed in several pathological biopsies, indicating possible deviations from the normal molecular characteristics of the chondroitin sulphate. Analysis of the main chondroitin sulphate fraction, obtained from pooled samples of normal tibial growth plate after fractionation on the macroscale, indicated that all three peaks contained both chondroitin-4 sulphate and chondroitin-6 sulphate and that they probably differed in their molecular weight.

The embryology of Arceuthobium pusillum

Megasporogenesis in Arceuthobium pusillum begins in March–April, 19 months after emergence of the pistillate aerial shoots. The embryo sacs are fully developed within 1 month. The first division results in a functional dyad and a nonfunctional dyad. The nucleus in the nonfunctional dyad divides once and the resulting nuclei disintegrate. Meiosis in the functional dyad follows immediately. Development of the embryo sac is of the bisporic Allium type. Staminate and pistillate aerial shoots flower in April–May. Fertilization occurs within several days after pollen has adhered to and germinated on the stigmas of pistillate flowers. One sperm nucleus fuses with the egg nucleus, the other with the polar nuclei. A haustorial extension then elongates downward into the ovarian papilla and becomes filled with a file of endosperm cells. Concurrently a uniseriate layer of endosperm has developed around the zygote. The endosperm then grows to a rather massive size before the zygote begins development. A transverse wall forms after the first division of the zygote. The terminal cell is bisected first, followed by bisection of the basal cell. Succeeding anticlinal and periclinal divisions result in growth of the proembryo. Embryonic protoderm is visible as a distinct tissue by the time the embryo has assumed an ovoid shape. When the seeds are forcibly expelled from their fruits in mid-September, the embryo has four distinct histological zones: protoderm, promeristem, ground meristem, and procambium.