A new cell line (MC840106) was established from the fetal mouse calvaria. It grew as monolayers. The modal chromosome number of MC840106 cells was 68, which was 66% of the total population of these cells.

The karyotypes of these cells consisted of typical acrocentric chromosomes and only one large metacentric chromosome.

An experimental study in ovariectomized rats was made to elucidate the effects of ovarian insufficiency on the bone metabolism in the tibia and the residual alveolar bone.

8-week-old Wistar rats were used in this study. The tibia and residual alveolar bone were examined histologically and histomorphometrically on the 2nd, 4th, 7th, 14th, 56th, 84th and the 168 day after the operation.

The body weight of ovariectomized rats increased remarkably compared with the control rats. The serum calcium level 8 weeks after the ovariectomy decreased temporarily but with no detectable changes in phosphorus levels as compared with the controls. Characterized histological changes showed disappearance of the trabecular bone in the tibial metaphysis upon 8 weeks in the ovariectomized rats. The rate of mineral deposition in the tibial endosteal surface showed no significant differences between both groups.

On the other hand, the marrow cavity of the residual alveolar bone expanded only in the ovariectomized rats, twelve weeks after the operation. Ovariectomy does not alteration in the reparative process of alveolar bone after the tooth extraction, nor the rate of mineral deposition in the residual ridge surfaces.

These findings obtained in this study suggest that the ovarian function plays an important role in sustaining the bone mass of the residual alveolar bone as well as the tibia.

Using an improved Richter’s method, the biphasic patterns (the A phase from 0 to 60 min after carbachol (CCh) administration; the B phase from 60 to 240 min) of mouse salivation responses to CCh were analyzed. The results obtained were as follows:

1. Pretreatment with atropine (1mg/kg, s. c.) strongly inhibited both the A and B phase of CCh-induced salivation.

2. Pretreatment with phentolamine (10mg/kg, s. c.), reserpine (4mg/kg, s. c.) and adrenalectomy inhibited the B phase more than the A phase.

3. Pretreatment with propranolol (10mg/kg, s. c.) slightly inhibited the B phase only.

4. Pretreatment with hexamethonium (20mg/kg, s. c.) did not affect either the A or B phases.

5. Nicotine (4mg/kg, s.c.) as well as CCh also displayed biphasic salivation in mice.

The above results suggest that the A phase of CCh-induced salivation is mainly caused by muscarinic action of CCh, whereas the B phase is mainly attributable to nicotinic action of CCh.

The effects of aging on regenerative processes of the junctional and sulcular epithelia after surgical excision of the gingiva were examined experimentally. The animals used were 5 to 51-week-old male rats (Wistar-strain) and divided into 3 groups according to their age: Group Ⅰ (5-6 weeks old), Group Ⅱ (14-15 weeks old) and Group Ⅲ (50-51 weeks old). The anilnals were sacrificed immediately after surgical excision of the gingiva by a sharp knife or a diamond point, and 1, 3, 5, 7, 14 days after the operation, and the gingiva and its neighboring tissues were morphologically studied under light and electron microscope. The results were as follows:

1. In non-treated animals, downgrowth of the junctional epithelium was seen in Group Ⅲ. The number of cell organelles such as mitochondria and tonofilaments in the junctional epithelium decreased in Group Ⅲ compared with that of Group Ⅰ or Ⅱ.

2. Under light microscopy, the regeneration of the gingiva was faster in Group Ⅰ, slower in Group Ⅱ and slower yet in Group Ⅲ.

3. Under electron microscopy, the regenerative changes of the gingiva such as reconstruction of the junctional and sulcular epithelia, formation of the basement membrane and functional arrangement of connective tissues fibers were faster in Group Ⅰ, slower in Group Ⅱ and slower yet in Group Ⅲ.

The effect of Bioglass on the amputated vital pulp was studied histopathologically using five male beagle dogs aged 14 months. The amputated pulps were divided into three groups according to their capping materials, i. e, group 1, Bioglass granules; group 2, mixture of Bioglass granules and calcium hydroxide powder; and group 3, calcium hydroxide powder. The pulp tissues and their neighboring hard tissues were examined 10, 20, 30, and 60 days after the vital pulp amputation.

The results were as follows:

1. The morphological healing process of amputated pulp tissues in group 1 and 2 was basically similar to that of group 3.

2. The evaluation of healing process of amputated pulp tissues showed a tendency to be more satisfactory in group. 3, less in group 2 and still less in group 1, but these defferences were not significant.

3. Dentin bridge was formed on the pulp surfaces in each group at the same ratio, but the width of dentin bridges in group 1 was thicker than those in groups 2 and 3.

4. Bioglass granules impacted in pulp tissue were phagocytized by numerous histiocytes, but no injurious effect to pulp tissue was seen in any of the sections.

Candida albicans (serotype A) T strain was isolated from a patient with denture stomatitis, and polysaccharides (crude polysaccharide, crude mannan, neutral mannan and acidic mannan) were extracted from the cell walls of the C. albicans T strain. A delayed skin reaction test and macrophage migration inhibition test were performed using the guniea pigs sensitized with the whole cells of C. albicans T strain.

Several fractions from C. albicans T strain were used as an antigen. A permeability increasing factor test was also performed in order to study inflammatory activity. In addition, experimental denture stomatitis was induced by inoculating crude polysaccharide under an acrylic plate. The results were as follows;

1. Crude polysaccharide was exhibited delayed skin reactivity. All extracted fractions were exhibited macrophage migration inhibitory activity.

2. All the extracted fractions were demonstrated to possess the permeability lncreasing activity.

3. Histologically, the chronic inflammation phase was observed in the palatal mucosa.

These results suggest that C. albicans mannan is the cause of denture stomatitis.

Four hundred and sixty seven human lymph nodes taken from 228 cases of biopsy or surgical operation materials of the head and neck regions were studied for the occurrence of intranodal salivary gland epithelia. Intranodal salivary gland epithelia were found in 33 lymph nodes of 22 cases (9,7%), but there were no age and sex preponderances in such occurrence. Occurrence of intranodal salivary gland epithelia tended to be more frequent in the lymph nodes located near the parotid gland. Intranodal salivary gland epithelia ware histologically composed of duct epithelial cells and serous acinar cells resembling to parotid acinar cells, but in places mucous acinar cells were found. Some cases showed that squamous epithelial metaplasia, oncocytic change and small cystic dilatation of salivary ducts with varying degrees of hyperplastic change of epitheria.

The results of the present study on lymph nodes in the head and neck regions suggest that the salivary gland epithelia in such lymph nodes may be retained for a long time as reported previously in studies on salivary gland epithelia in intraparotid lymph nodes. However, there is no definitive evidence to support the concept that some salivary gland lesions such as adenolymphoma and benign lymphoepithelial lesion originate from the intranodal salivary gland epithelia.

The effects of protamine and heparin on tumor angiogenesis and angioarchitecture were investigated. Following production of DMBA-induced tumor in golden hamster tongues, protamine, heparin, saline in ratio of 60mg/kg/day were administered subcutaneously 12 times over 2 weeks. Vascular pictures through intravascular injection of BaSO₄ solution, India ink, and injection resin were observed by means of angiography, microscopy and SEM. There were macroscopically many protruded tumors and histologically squamous cell carcinomas. They were characterized by combined and well-differentiated growth types. In the protamine group extravasation of carbon particles from the tumor vessel walls were slight, but was much more frequent in the heparin group. The vascular level was significantly lower in the protamine than in both the heparin and saline groups. Hypervascularity of the tumor was observed by means of microangiography in the heparin group, but not in the protamine and saline groups. Newly formed vascular buds were infrequent in the protamine group, but more frequent in the heparin group.

The angioarchitecture around the carinoma cell nests looked like a cylinder composed of 3 vascular layers. Numerous constrictions of the capillaries on the outer surface of the cylinder were apparent in the protalnine group. Mast cells were not observed in the tumor sites of all 3 groups, but near by vessels surrounding the tumor. Thus, it is suggested that tumor angiogenesis was inhibited by protamine and promoted by heparin.

A comparative morphological study was made of both vascularized and free bone tissues in process of angioarchitecture and bone remodeling. Mandibular bone fragments, both those with and without alveolar inferior vessels, of 39 mongrel adult dogs were regrafted. Transparent and H.E. preparations by means of India ink injection, SEM by means of mercox injection and vascular levels measured 7 times over six months.

In the free bone tissues, new vessels from the surrounding recipient bed formed a fine network after infiltrating the spongy area, followed by the formation of new bone tissue along the spongy trabeculae. New vessels from the bone marrow penetrated into the Volkmann’s canals of the compact area, where regrafted bone absorption and new bone apposition was taking place. Angioarchitecture and bone remodeling in the regrafted bone tissue advanced gradually, and the bony union between the regrafted and recipient bone tissues was achieved. On the other hand, in the vascularized tissue previous vessels and bone formation process continued in both the regrafted and recipient bone tissues. In the free bone tissue, the vascular levels on the 7th or 14th day were conspicuously low. However, in the vascularized bone tissue the levels showed that blood circulation was maintained even on the first or 7th days, and then gradually returned to normal levels.

In all the angioarchitecture and bone remodeling processes after regrafting the vascularized bone and the spongy areas tended to be superior to the free bone and the compact areas in both rate and area of recovery.

A case of solitary juvenile xanthogranuloma occurring in the floor of the mouth is presented. The patient was a 7-year-old girl who had been suffering from Ewing’s sarcoma of the mandible. In the surgical operation material consisting of the mandibular bone and its surrounding soft tissues, a thumb’s tip-sized and well-circumscribed tumor with yellowish brown in colour and elastic soft in consistency was found in the region of the floor of the mouth. Histological examination revealed that this tumor was composed of densely-packed foamy histiocytes and Touton giant cells. Small mononuclear cells, loose fibrous connective tissues, and small vessels were scatterd throughout the lesion. A review of the literature has revealed only two previously documented cases of juvenile xanthogranuloma occurring solitarily in the oral cavity.

The biological effects of three types of bio-active glass, developed by Nippon Kogaku K. K., on bone tissue was studied in rats. The results were as follows:

(1) No toxicity of bio-active glass was seen.

(2) Implanted bio-active glass was surrounded by newly formed bone tissue.

(3) Tight adhesion between newly formed bone tissue and bio-active glass was confirmed.

These findings suggest that the bio-active glass is a useful material for dental implants.