The giant cell fibroma. A review of 103 cases with immunohistochemical findings.

This article reports a series of 103 cases of giant cell fibromas occurring in the oral mucosa. The commonest location was the gingiva, followed by the tongue and the buccal mucosa. The mean age of the patients was 27.7 years, and the median age 21 years. Microscopically, the tumors were characterized by the presence of large stellate or angular cells, which occasionally contained several nuclei. Immunohistochemical stains showed that the cells were vimentin-positive but negative for S-100 protein, cytokeratin, leukocyte common antigen, and neurofilament.

Histochemical analysis of enzymes involved in the formation and metabolism of the nasal septal cartilage.

Formation of the nasal septal cartilage in prenatal and neonatal rats was studied histologically and by histochemistry to determine the manner, degree and participation of the nasal septal cartilage in midface growth and in bone formation of the face. Chondrogenesis of the nasal septal cartilage started at the 13th embryonic day, premaxillary and vomerin bone formation at the 14th embryonic day and endochondral bone formation of the septo-presphenoid area at the 17th embryonic day. After differentiation of the nasal septal cartilage, this cartilage supported ethmoid bone formation by endochondal ossification in the septo-presphenoid area. Nasal septal cartilage showed intense activity of lactate dehydrogenase, NADH2-diaphorase and a moderate activity of acid phosphatase, whereas premaxillary and vomerin bone showed intense activity of alkaline phosphatase. Osteoblasts showed intense activity of alkaline phosphatase, lactate dehydrogenase and NADH2-diaphorase and osteoclasts showed intense activity of acid phosphatase. During the embryonal period growth of the nasal septal cartilage could occur in an ethmoido-rostral direction supported by endochondral ossification and growth in length and height supported by apposition and interstitial growth.

The lateral periodontal cyst. A histopathological and radiographic study of 32 cases.

The lateral periodontal cyst is a developmental odontogenic cyst usually found in the premolar area of the lower jaw. The clinical, radiographic and histopathological features of 32 previously unreported lateral periodontal cysts were reviewed. In four cases the follow-up, which extended over several years, was also studied. Different theories of pathogenesis are discussed.

Enzyme histochemical analysis of craniofacial malformations induced by retinoids.

Craniofacial malformations were induced in 256 embryos from 32 pregnant rats by a single intraperitoneal injection of 10 mg/kg etretinate at 8.5 days gestation. The litters developed several malformations including microtia, low set and dorsally placed outer ears, defective middle ear ossicles, short cochleas, defectively differentiated Meckel's cartilages, micrognathia, rudimentary malar bones, lateral facial clefts, fistulas, and skin tags, all of which tissues are derivatives of the first and second branchial arches. The teratogenically induced syndrome shows similarities to the mandibulofacial dysostosis syndrome in man. The defects were accompanied by a change in the histochemical differentiation and location of various enzymes in the craniofacial tissues.

Enzyme histochemical analysis of Meckel's cartilage.

Osteogenesis of the body of the mandible in embryonic and neonatal rats was studied histologically and by histochemistry to determine the role of Meckel's cartilage in bone formation. Meckel's cartilage showed intense activity of lactate dehydrogenase and NADH2-diaphorase and weak activity of acid phosphatase, indicating a functioning citric acid cycle, pentose phosphate shunt and a capacity for anaerobic metabolism. The activity of these enzymes declined after hypertrophy of Meckel's cartilage. Alkaline phosphatase was the major enzyme of mineralising mandibular osteoid and was present in the osteoblasts and osteoprogenitor cells but not in Meckel's cartilage. After the differentiation of Meckel's cartilage and intramembranous bone, Meckel's cartilage supported mandibular bone formation by endochondral ossification in the anterior part of the mandible.

Lactate dehydrogenase isoenzyme changes during facial development.

Lactate dehydrogenase activity (LDH) was demonstrated by a histochemical technique in free, dissected, facial processes of rats from the ninth embryonic day. Facial processes of embryonic rats aged 9-15 days were analysed by isoelectric focusing for their isoenzymic distribution of LDH. A dominance of LDH-5, LDH-4 and LDH-3 isoenzymes was observed. As a comparison, LDH isoenzymes from mandibular and maxillary processes of rat embryos aged 9-11 days revealed only LDH-5 and, to a smaller extent, LDH-4. These results constitute evidence for prominent anaerobic metabolism in these tissues during early facial development. Intense staining for LDH was seen in surface epithelium, respiratory epithelium and in myogenic and osteogenic areas.

Metaplastic formation of bone and chondroid in flabby ridges.

The present study was undertaken to demonstrate certain histological characteristics of biopsies from flabby ridges. Our results show that metaplastic formation of bone and chondroid are found in specimens from patients where radiopaque structures were visible on radiographs outside the alveolar ridge. Another aim was to demonstrate the metabolic activity of these zones especially as formerly they were believed to be non-vital. The cells in the vicinity of the bone and cartilage showed a higher activity of all metabolic enzymes studied than did ordinary fibroblasts; also the osteocytes and chondrocytes showed positive reactions for several enzymes.

Changes in alkaline-phosphatase isoenzymes of hard tissue origin during facial development in the rat.

Non-specific alkaline phosphatase (APase) activity was demonstrated histochemically in the hard-tissue-forming areas of the developing rat face from the 14th embryonic day. Isoenzyme distribution of APase was recorded by isoelectric focusing. Three APase isoenzyme bands with lower isoelectric points than adult forms were recorded. Inhibition studies with levamisole dexamisole, L-p-bromotetramisole, D-p-bromotetramisole, diphosphonates and urea showed the embryonic isoenzymes to have the same sensitivity as the adult forms except to urea. Heated to 56 degrees C, both embryonic and adult APase were rapidly inactivated. The differences between the embryonic and adult forms of APase may represent the expression of different gene loci or a difference in post-translational modification.

Infraocclusion of primary molars: a histologic study.

In order to analyze the occurrence and character of ankylosis in primary molars in infraocclusion, 102 primary molars, 62 in infraocclusion and 40 in normal position, in children aged 3-17 yr, were studied histologically. Ankylosis was demonstrable in most of the infraoccluded teeth while ankylosis was not found in teeth with normal positions. The ankylosis was always located at the inner root surface. Progression of the resorption of the root with age was seen in both groups of teeth. In teeth of younger children, in contrast to teeth of older children, the ankylosis was never found in the cervical portion of the roots. In the mandible, a thicker buccal marginal bone crest could be found in infraoccluded teeth than in teeth in normal position. Bone biopsies revealed no pathologic changes. Pulps of infraoccluded teeth more often demonstrated degenerative changes like fibrosis and calcifications. It is suggested that ankylosis is a local phenomenon, most likely due to developmental disturbances of the periodontium, and that ankylosis in infraoccluded primary molars is not a static condition but part of an ongoing process during root resorption.

Effect of 50 kV irradiation on enzyme activities of growing rat bone. A histopathologic and enzyme histochemical investigation.

Young rats were exposed to 2, 5, 8 and 10 Gy 50 kV local irradiation. The epiphyseal region of the proximal tibia was examined with histopathologic, histochemical and enzyme histochemical methods 1 to 90 days after irradiation. One day after irradiation, a decrease in alkaline phosphatase activity was noted and increased activity was found for acid phosphatase, NADH2-diaphorase and glucose-6-phosphate dehydrogenase, especially after 8 and 10 Gy, but also after 5 Gy. Three days after irradiation, all enzymes showed an increased activity and on day 7 the findings resembled those on day 3. Thirty days after irradiation, a return to normal conditions was observed. The most marked morphologic changes were swelling of cells in the hypertrophic cell zone, disturbed order of cells in the zone of proliferation and an increased number of osteoclasts in the metaphyseal bone. These alterations appeared 1 to 3 days after irradiation and normal morphology was seen on day 30 after 2, 5 and 8 Gy and 90 days after irradiation with 10 Gy.

Enzyme histochemical studies of acid phosphatase isoenzymes in induced heterotopic bone formation in guinea pigs.

A bone induction model was used to study the effect of different pretreatments and inhibitors added to the substrate media used for the histochemical demonstration of acid phosphatase activity. Two different acid phosphatases (AcP) were demonstrated. The AcP of matrix-producing cells exhibited resistance to pretreatment with EDTA while it was sensitive to tartrate added to the incubation medium. The AcP in dentin resorbing cells was EDTA sensitive but resistant to tartrate. The AcP activities in both resorbing and matrix-producing cells generally sensitive to fluoride, copper and molybdate. In some of the dentinoclasts, fluoride resistant AcP was observed. The results suggest previous investigations on normal bone formation, suggesting that at least two different isoenzymes of AcP exist. One of these seemed to be related to matrix production and mineralization of the new heterotopic bone.

Enzyme histochemical studies of induced heterotopic cartilage and bone formation in guinea pigs with special reference to acid phosphatase.

Heterotopic bone and cartilage formation was studied in a bone induction model in abdominal muscles of guinea pigs using the demineralized allogenic dentin as inductive material. The light microscopic study showed high activity of acid phosphatase (AcP) and leucine aminopeptidase (LAP) in young matrix-producing cells. The highest activity was seen in cells surrounded by unmineralized matrix. In the surrounding matrix there was strong staining of AcP, especially in matrix with high glycosaminoglycan content. Electron microscopic studies of AcP in sections from unfixed frozen tissue showed intracellular activity mainly located in lysosomes. Extracellular AcP activity was found in matrix vesicles in the newly formed hard tissue. It was most pronounced in areas of cartilaginous differentiation. By means of energy dispersive X-ray microanalysis in a scanning transmission electron microscope, the deposits were confirmed to contain led precipitates. With the exception of some lysosomal staining, prefixation with formaldehyde prevented demonstration of the enzyme activity. Both AcP and LAP may be involved in degradation of organic components of the matrix which enable the matrix to mineralize.

Ameloblastic fibroma.

Four cases of ameloblastic fibroma appearing in the posterior maxilla and the cupsid area of the mandibula are presented. One of the lesions appeared in the wall of a cyst and another was found in connection with a cyst. The treatment is conservative but the tumor needs close follow up for possible recurrence.

Odontogenic keratocysts: a clinical and histological study with special reference to enzyme histochemistry.

Of a total of 1,420 odontogenic cysts, 52 (3.3%) were diagnosed as odontogenic keratocysts. Clinical and histological findings in these 52 cysts are reported. Frozen sections of 26 of the keratocysts were incubated to show the following enzyme activities: NADH2- and NADPH2-diaphorase, glucose-6-phosphate dehydrogenase, glutamate dehydrogenase, acid phosphatase, leucine aminopeptidase and ATPase. Furthermore, keratinization was studied with the rhodamine B method and lipids with the oil red O, the OTAN and the acid hematein methods. Sections from epidermis, oral mucosa, radicular cysts, residual cysts and follicular cysts served as reference material. The oxidative enzymes showed strong activity in the keratocyst epithelium which contrasted with weak activity in the reference cysts. Acid phosphatase activity was weak in all epithelia except that in keratocysts, which displayed a marked activity. In the fibrous capsule of the keratocyst a high activity of leucine aminopeptidase was recorded. This high activity contrasted with a weak activity in the reference material. The significance of the histochemical results in relation to the aggressive behavior of the keratocyst is discussed.

Sutural closure in rabbit and man: a morphological and histochemical study.

Some aspects of normal obliteration of sutures in rabbit and man were studied histologically and it was found that suture closure took place by intramembranous ossification in specific areas of trans-suturally arranged, tendon-like tissue. Histochemically these areas demonstrated high activity of oxidative enzymes.