The mucous epithelium of the rat palatal rugae was observed by light and electron micros-copy. The shape of the epithelial-connective tissue junction (ECJ) of the rat palatal mucosa was found to be composed of ridge-typed papillae (RTP) which ran in an antero-posterior di-rection (APD) . The purpose of the study is to investigate the differentiation of the basal and spinous layer in the palatal mucosa which consists of RTP by the observation of the shape of the ECJ and the morphology and structure of the constituent cells. Results: (1) The RTP which ran in the APD appeared to be related to the direction of the blood vessels and collagen bundles within the submucous and papillary layers. (2) The basal cells were classified into Bl, B2 and B3 cells for the sake of convenience from the morphological and structural characteristics. Polyhedral spinous cells located within the lower third of the spi-nous layer were also classified into SlP and SlI cells. (3) The B1 and SlI cells were mainly distributed in the interpapillary area (I-area), the B2 and SIP cells in the papillary area (P-area) and the B3 cells between the P- and I-area (PI-area) . (4) The cell division was observed chiefly in the I- or PI-area in the APD and the divided cells appeared to become B1 cells. The B1 cells transitionally changed into B2 or B3 cells and finally into SlP cells in the P-area, and 511 cells in the I-area.
The purpose of the study was to investigate the early responses of microvasculature, especially increased vascular permeability (IVP) to the light-continuous mechanical pressure stimulation. The hamster cheek pouch was used as an in vivo model of periodontal vasculature. FITC-dextran (molecular weight 150, 000) was injected intravenously as a tracer and then intravital and electron microscopic observations were made and also the role of histamine in IVP to the mechanical stimulation was studied. The results were as follows: 1. Blood flow in postcapillary venules (PCV) (about 50 μm in diameter) was not interrupted under the stimulation of 0. 1g. IVP at PCV was observed at 5 minutes after the beginning of this stimulation by fluorescein intravital microscopy. 2. Electron microscopic observations revealed that this IVP was attributed to the formation of gaps (0.1. ` 0. 5 . μm) between endothelial cells of PCV without stasis and degranulation of mast cells and that monocytes and platelets were attached to the endothelial cells in the lumen. These gaps were seen until 30 minutes after the beginning of the stimulation. 3. Pretreatment with pyrilamine, a histamine H1-receptor antagonist, inhibited the appearance of IVP at 5 minutes after the beginning of the stimulation, but it didn't completely reduce IVP appearing after 10 minutes of stimulation. It was suggested that histamine played some roles in IVP which appeared at 5 minutes after the beginning of the stimulation, but was not essential after 10 minutes.
The possibility of the dental lamina as a source of odontogenic cyst was investigated. The mandibular first molar tooth germs with the dental lamina and surface oral epithelium were cut from 17.5-day-old C3H mouse embryos. The following 5 kinds of grafts were prepared: (I) recombinant of the dental lamina and dental papilla, (II) dental lamina, (ILL) dental papilla, (IV) recombinant of the oral epithelium and dental papilla and V oral epithelium. After the renal subcapsular transplantation to the 3-month-old syngeneic male mice, each graft was harvested at timed sequences from 2 to 24 weeks and was examined histopathologically. The recombinant of the dental lamina and dental papilla (I) grew into a cyst lined by parakeratinized stratified squamous epithelium. The cyst enlarged gradually and might be compared to the odontogenic keratocyst of the human being. The recombinant of the oral epithelium and dental papilla (IV) and the oral epithelium (V) developed into a cyst lined by orthokeratinized stratified squamous epithelium which differed from the epithelium seen in Experiment (I). The dental papilla (1g) grew to be a bone tissue while nothing developed from the dental lamina (II). These results suggest that the dental lamina is one of the sources of the odontogenic kera-tocyst and the dental papilla plays an important role in its histogenesis.
The 2.91; b Sac I fragment ( E J2.9 ), which lacks the previously reported promoter/enhancers of the activated human c-H-rus-1, was used to study the interaction with the tumor virus promoter /enhancers or with the activated c-myc. When EJ2.9 constructs linked to the viral promoter/ enhancers or to a viral enhancer even in the antisense orientation was transfected to the mouse cells, 16-39% of the foci induced with those linked in the sense orientation were formed. Fur-ther, the transforming activity decreased dramatically when the deletion was introduced from the upstream Sac I site to the 61 bases (-61) upstream of translationalinitiation codon, but the deletions to -144 did not significantly change the activity. Cotransfections with the activated c-myc were found also to enhancethe transforming acti-vity of EJ2.9 constructs either with or without the LTR linked in the antisense orientation. The transfected ras and myc were expressed as 1.2 and 2.5kb mRNAs, respectively, in each transfor-mant. The in vitro mutagenesis suggested that the c-myc protein wasinvolved in the enhance-ment. These results raise the possibility that the viral enhancers activate a cryptic promoter (s) within the region between -1 and -144 of p21 initiation codon by interacting with the region between -61 and -144 and that the c-myc protein also activates the same or different cryptic promoter (s) within the intron O or noncoding region of exon I, thus leading to the enhancement of the EJ2.9 transforming activity.
This study was carried out to clarify the mechanism of stimulating effects of low power He-Ne laser irradiation on wound healing process of rat palatal mucosa. Experimental wounds were made in 8-week-old male SD rats by surgically excising mucoperiosteum in hard palate. Fibroblasts were cultured from the scar tissue one month after the excision. Cells were investigated ultrascopically and the effects of He-Ne laser irradiation were examined by measuring DNA and collagen synthesis. Thermal change of the medium was also monitored. Cultured cells from the palatal wounds exhibited features of myofibroblasts. They exhibited well -developed bundles of microfilaments in the cytoplasm and had nuclei with foldings. Single irradiation of lie-Ne laser at 28J/cm2 stimulated uptake of [3H] Thymidine into myofibroblasts and the stimulating effect decreased time dependently. There was no significant change in collagen synthesis. No thermal change was detected during irradiation. Ultrascopically, dilatation of rER was observed immediately after irradiation at 28J/cm2. But there was no modification in other cytoplasmic structures. The author concludes that He-Ne laser irradiation stimulates DNA synthesis of myofibroblasts without any degenerative changes in the organelle.
Five cases of familial and idiopathic gingival fibromatosis were reported. One case exhibited peculiar histologic features, which consisted of active growth of the fibroblastic cells. One hundred and ninety-six cases of gingival fibromatosis, whose clinical and/or pathologic findings were known, were
For the purpose of investigating to clarify the differential diagnosis and treatment of TMJ dysfunction, The TMJ sounds were analysed acoustically using accelerometers. The 101 TMJ sounds were recorded from 20 patients. Jaw movement and electromyogram (EMG) were recorded imultaneously. Comparison of the TMJ sounds to the jaw movement and EMG were madse. The following conclusions were obtained: (1) TMJ sounds were classified into three clusters according to the total energy and band width. (2) It is possible to divide the changing of jaw moving velocity into three patterns. (3) It was found that the signal characteristics have relevance to the changing patterns of jaw moving velocity. (4) The acoustical study of TMJ sounds bring on the variable informations to clinical dentistry.
The possibilities of bone and soft tissue ablation without thermal damage by 248 nm KrF excimer laser irradiation were examined. A defect was made on the rat tongue by laser at pulse width: 15 nsec, power density: 12 W/cm2, pulse repetition rate: 20 Hz and irradiated time: 60 seconds. The same size defect was made by stainless steel surgical knife for control. The tongues were examined histopathologically at timed sequence from 1 hour to 7 days after operation. The rat femur was cut by laser at pulse width: 15 nsec, power density: 2. 6 kW/cm2, pulse repetition rate: 30 Hz and irradiated time: 3 minutes. The femur was amputated by dental diamond disc for control. The femurs were examined histopathologically at timed sequence from 1 hour to 16 weeks after operation. The rat tongue was easily excised with little thermal injury by laser irradiation, and its healing process is almost the same as that of the control. The laser irradiation had no hemostatic effect. The femur could be amputated by laser irradiation but its wound healing was prolonged. The laser ablation stump showed massive necrosis probably due to the thermal injury and these necrotic bones likely disturbed the wound repair. The degree of the thermal injury by the excimer laser irradiation might depends on the irradiation condition because the condition of bone amputation was stronger than that of tongue excision.
Interactions between the epithelium and mesenchyme were very important in tooth develop-ment. When these relationships changed qualitatively or quantitavely, developmental tooth anormalies or odontogenic lesions might develop. In order to clarify this hypothesis, we exa-mined the effects of discrepancy in the number of enamel organs and dental papillas on histo-and morpho-differentiation of the recombinants by renal subcapsular transplantation. Five kinds of recombinants were prepared from the enamel organs (E) and dental papillas (M) of the mandibular first molars of 17-gestational-day C3H mice: group 1 (E/M=2/6), group 2 (E/M=3/5), group 3 (E/M=4/4), group 4 (E/M=5/3) and group 5 (E/M=6/2) . After 28 days of transplantation, all the grafts were harvested and examined roentogenographically and histopathologically. All the grafts developed into teeth. The teeth of groups 1 and 5 were independent from each other and the teeth of groups 2, 3 and 4 fused with each other by dentin. The number and size of the teeth depend on the number of M and the differences between E and M of the recombinants, respectively. The smaller the difference, smaller was the teeth size. The cysts lined by the keratinizing squamous epithelium developed from E-rich recombinants.. These could be comparative to the compound odontoma, fused teeth and odontogenic kerato-cyst of the human being respectively. It might be speculated that the histogenesis of these lesions might be related to the quantative change in the epithelial-mesenchymal interactions of oclontogenesis.