骨吸収の際に主役をなす細胞は破骨細胞であるということは異論のないところであるが, その過程において骨芽細胞が重要な役割を果しているらしいことが主としてin vitroの実験から最近提案されている。そこで本実験はin vivoにおける骨吸収過程における骨芽細胞の関与の有無について形態的に明かにしようとしたものであるが, 更にこれら形態変化とともに血清カルシウム値および血漿中ビタミンD₃代謝産物量を同時に検索し, それらの関連性について検討を加えたものである。
低カルシウム・ビタミンD欠乏食で飼育した成長期ラットの骨組織はクル病の状態を呈しており, この動物に生理量のビタミンD₃を投与すると, 主として骨髄側に骨吸収を生じた。その過程を検索すると, まずビタミンD₃投与後6時間で血漿中1α, 25 (OH) 2D₃が上昇し, 高値を示し, それと同時に紡錘形を呈していた骨芽細胞に形態変化が生じ, 立方形細胞となった。その後, 投与12時間目になると破骨細胞数の増加および血清カルシウム値の上昇がみられた。更にその後, 骨吸収面の拡大が起こり類骨組織の減少がみられ, 骨組織が改善された。また経時的に検索した破骨細胞数の増加は多核の細胞によるもので, 単核の細胞数に変化はなかった。
以上のごとく, 破骨細胞性骨吸収が起こる以前の初期過程において, 骨芽細胞の形態変化が血漿中1α, 25 (OH) ₂D₃の上昇と関連してみられたことは, 1α, 25 (OH) ₂D₃がそのリセプターをもつ骨芽細胞に直接作用し, 続いて起こる破骨細胞数の増加および活性化に何らかの役割を果たしていることを示唆するものである。

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マウスの上顎骨口蓋突起の成長に伴う正中口蓋縫合の形成を光顕, 実体顕微鏡さらに走査電顕で調べた。
この縫合はL字形をした左右の上顎骨口蓋突起の間隙に形成された。縫合の前方部は細胞の凝集と膠原線維束形成の2段階で形成された。縫合の後方部は細胞の凝集, 二次軟骨細胞の出現, 軟骨結合さらに二次軟骨の骨化の4段階で形成された。
そこで, 縫合の前方部と後方部の主成分はそれぞれ膠原線維束と二次軟骨であった。

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サケ科魚類の口腔および咽頭には多数の歯が植立し, その分布状況は骨の形態や配置と共に属や種の重要な分類形質として認められている。一方, サケ科魚類数種においては成熟期に達すると口部の骨格系および歯系に著るしい性差が生ずると報告されている。しかし, その詳細については不明なことが多い。そこでサケ科サケ属サケ, Oncorhynchus keta, の産卵期成魚の口部骨格系および歯系に関してその大きさや歯胚率等について測定し雌雄間で比較した。サケ雄成魚の口部を構成する骨は同年齢・同体長の雌成魚に比べて大きく, それら骨上に植立する歯の長さも大きい。この傾向は口部両顎を構成する骨や歯においてより顕著であった。さらに, 雄成魚の顎骨上の歯の数は雌成魚より少ないが, 機能歯の割合は高く, 脱落歯の数も多い。このような性差は産卵・受精期における雄成魚の攻撃的行動等の生活習性と深く関連していると推測された。

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経胎盤法による歯原性腫瘍の誘発を目的とし, 妊娠後期のSprague-Dawley系ラットにN-methylnitrosourea (MNU) 50mg/kg体重を1回胃内に投与し, 胎仔の出生後における歯原性腫瘍の発生状態について検索した。実験動物の観察期間は生後22日から1年11カ月までであった。屠殺あるいは死亡した実験動物は顎骨部を軟X線的ならびに組織学的に検索した。検索を行なった動物数は実験群170匹, 対照群20匹であった。実験群の動物は全般に成長発育が悪く, 体重の増加も少なかった。また, 比較的短期間で死亡するものが多く, 6月齢から1年6月齢で死亡したラットが75%を占めていた。実験群のラットの中で3月齢ぐらいから下顎骨に膨隆を示すものが出現し, 6匹の下顎骨に歯原性腫瘍の発現が認められた。これらの腫瘍はX線的には周囲との境界が明瞭で, 内部に放射状の不透過物を含むX線透過像を示していた。組織学的には, 腫瘍は不規則な歯牙様硬組織歯乳頭様結合組織および角質変性の著しい上皮組織からなり, ヒトの歯牙エナメル上皮腫 (エナメル上皮歯牙腫) に類似していた。腫瘍と周囲組織との境界は明瞭で菲薄な骨組織あるいは線維性組織で境されていた。腫瘍と下顎切歯との関連では, 切歯の象牙質と腫瘍中の硬組織間に移行像がみられ, また切歯エナメル上皮と腫瘍の上皮成分との移行像もみられた。従って, 本腫瘍は下顎切歯のエナメル上皮より生じたものと推定された。なお, 腫瘍と下顎臼歯との問には直接の関連は認められなかった。
以上のように癌原性物質の経胎盤性投与によっても発現頻度は低いが, 歯原性腫瘍が誘発されることが明らかとなった。今回みられた歯原性腫瘍はすべて下顎骨内に発生しており, その組織像は経胎盤法にもかかわらず既報の出生後に投与したものと同様の組織像を示したことは大変興味深いことであった。

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Calcification was found in cell cultures prepared from the bone of human mandible bone. The bone fragments were obtained during a mandibular retropositioning operation of an adult human. The primary bone was cultured in α-MEM medium with calf bovine serum at 37°C and 5% CO₂ after the surrounding soft tissue and the periosteum of the bone fragments were removed. The outgrowth of cell from the primary bone were transfered every five to seven days. The cultured cells were observed by phase-contrast microscopy, alizarin red S staining, electron microscopy and X-ray probemicroanalysis. Colony formation was observed microscopicolly at two days intenals. Calcification of the colonies was confirmed by alizarin red S staining. The construction of needle-shaped crystals and fibres formed from collagen were observed by electron microscopy view. The Ca and P ratio obtained X-ray probe microanalysis from the calcium precipitation in the colony indicated the presence of hydroxy apatite.

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An esteroprotease (TAMEase) with the molecular weight of 27.5K was purified from male mice submandibular glands and then the specific antiserum to this purified enzyme was prepared. The characteristics of the TAMEase molecule such as the tissue and species specificities and the development were studied by enzyme immunoassay and immunoblot assay using the antiserum. The effect of androgen on the biosynthesis of the TAMEase molecules was also investigated. Furthermore, cytosol and nuclear levels of androgen receptors in mouse submandibular glands were analyzed. It was confirmed that the TAMEase molecule was specific to mouse submandibular gland and the biosynthesis of TAMEase molecules was affected by androgen. Immunoblot assay of crude extracts from male mouse submandibular glands revealed that the TAMEase molecules showed cross-reactivities with anti-TAMEase antibody at 30.5K, 27.5K, 16.5K, 16K and 12.5K bands. A sexual difference existed in the development of TAMEase molecules. In male mouse submandibular gland, the TAMEase molecule, which had with the molecular weight of 27.5K and enzymatic activity, appeared 4 weeks after birth and it increased with age. In females, TAMEase molecules with the molecular weights of 30.5K and 16.5K were detected at 3 weeks of age, but these molecules showed no enzymatic activity. In the females TAMEase molecule of 27.5K with enzymatic activity appeared 5 weeks after birth. These findings suggest that the 30.5K and 16.5K molecules were inactive precursors such as. In males, androgen receptor levels in the nuclei increased with the development of the TAMEase concentration which is considered to be a marker for aging. It is suggested that the androgen receptor acts as a mediator when the biosynthesis of the TAMEase molecules is regulated by androgen.

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Changes in the ultimate loads required to extract the mandibular and maxillary 1st, 2nd and 3rd molars from the dissected jaws were examined 1, 2, 4, 8, 16 and 24 days following oral administration of a lathyrogen, beta;-aminopropionitrile (BAPN). The average amount of water taken by the rats was fairly constant but because their body weight increased during the experimental period, the average dose of BAPN decreased gradually from 331 to 192mg/Kg b. w. In the control groups, the ultimate loads increased gradually from the beginning to the end of the experimental period. They were 34.4, 26.9 and 13.6N (newtons) in the mandibular 1st, 2nd and 3rd molars and were 34.2, 30.6 and 18.0N in the maxillary 1st, 2nd and 3rd molars respectively at the end of the experimental pe-riod. In the experimental groups, they were 9.9, 10.2 and 8.4 N in the mandibular 1st, 2nd and 3rd molars and were 13.5, 14.6 and 10.9N in the maxillary 1st, 2nd and 3rd molars respectively at the end of the experimental period. The biggest values of the percentage reductions of the ultimate loads were 73, 71 and 51 in the mandibular 1st, 2nd and 3rd molars and were 64, 58 and 64 in the maxillary 1st, 2nd and 3rd molars respectively during the experimental period. From an analysis of the results, it is suggested that the effects of BAPN appeared rather rapidly in the teeth with imm ature periodontal ligaments and that the functioning teeth tended to be affected more severely by the drug

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Two different jaw opening responses elicited by a single stimulation of the temporomandibular joint (TMJ) were recorded from the myohyoid nerve in a-chloralose-anesthetized cats. One featured an early response (ER, 5-8 msec latency) and the other a late response (LR, 18-20 msec latency). The LR which was suppressed slowly by application of 2% Xylocaine to the TMJ was elicited by a lower stimulus intensity than that of ER. Mechanical stimulation of the TMJ was more effective for producing an LR than an ER. These results indicate that an LR originates from mechanoreceptors of TMJ having thick afferent fibers, and that an ER originates from nociceptors with thin afferent fibers. The LR amplitude produced by a test stimulus to the TMJ was suppressed by the conditioning stimulus to the TMJ. Similar results were obtained when the same test was applied to the periodontal ligament. When a conditioning stimulus was applied to the TMJ while a test stimulus was applied to the periodontal ligament and then reversed, the inhibitory effects elicited from both regions were smaller than when the conditioning and test stimulation were applied to a single site, The LR elicited by the movement of the jaw changed with the change in the position of condyle and the velocity of the movement. These results indicate that mechanoreceptors in the TMJ were specialized in their distribution, and the density of mechanoreceptors in comparison with that of nociceptors in the TMJ is greater than that in the periodontal ligament and oral mucosa.

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Mouse cytomegalovirus (MCMV) infected cells were investigated for analysis of MCMVlatent infection and reactivation of MCMV in vivo. BALB/c mice were infected ip with 2×10^5.0 PFU of MCMV (Smith strain), which was grown in BALB/c mouse embryo cells (MEC) and the infectivities in the spleen, liver, pancreas and salivary gland were assayed with MEC after various days of in-fection. MCMV could be detected temporarily in the spleen and liver for 3-5 days after i nfection but MCMV could be recognized after 8 weeks in the pancreas. In the case of the salivary gland, MCMV could be detected 28 weeks after infection. On the other hand, neutralizing antibody in the sera appeared from 2 weeks after the infection and MCMV infectivity in the pancreas was gradually extinguished with the increase of antibody titer but that in the salivary gland was not.
When thin-sections of salivary glands were stained with hematoxylin -eosin, about 91% of giantcells were observed in the intercalated duct of salivary gland and furthermore the MCMV anti gen wasproved to be present in the giant cells by indirect immunofluorescent antibody staining.
When mice were administered with cyclophosphamide (CY) aft er 10 weeks of MCMV infection, the number of suppressor T cells, helper T cells, natural kill er cells and B cells in splenocytes was extremely reduced and the giant cells appeared again in the interc alated duct of the salivary gland.
These results clearly indicated that MCMV can infect specifically the intercalated duct of the salivary gland and could change to a persistent and then a latent state in the intercalated duct cells.

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The a. malaris of the cat was studied by utilizing the acryl plastic injection method. This artery generally arose from the infraorbital artery in common with the anterior nasal dorsal artery, or rarely in common with the anterior superior alveolar artery. It gave rise to the inferior oblique and the third palpebral branches at the superoanterior end of the origin of the obliquus inferioris muscle. The former always was a stout vessel as it was also in some mammals. The latter was especially developed in the cat and divided into the third palpebral glandular branch and others to supply the whole third palpebra. The a. malaris gave rise to the periosteal and the nasolacrimal branches on the orbital surfaces of the lacrimal and frontal bones. It finally terminated in the medial superior and inferior palpebral arteries. They, however, did not form superior and inferior arterial archs in the respective palpebra as observed in the rabbit. The medial inferior palpebral artery gave rise to the nasolacrimal, the lacrimal sac, the nasal radical, the ocular orbicular, the infraorbital marginal, the conjunctival and the cutaneous branches. The medial superior palpebral artery gave rise to thesuperior palpebral levator and the supraorbital marginal, after giving off the lacrimal sac and the nasal radical branches. The cutaneous branch anastomosed with the branches of the superficial temporal artery.
The anterior nasal dorsal artery arising in common with the a. malaris in most cases formed a fine network with many fine branches of the a. malaris, which spread on the face, especially in an area centeral to the medial canthus.

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The present study shows that Bacteroides gingivalis-treated murine peritoneal macrophages produce interleukin-1 (IL-1)-like factor (s) which are stimulatory for the osteoblastic cell line MC3T3 -E1. Macrophage-conditioned medium (MCM) was prepared from peritoneal macrophages harvested from mice on day 3 after injection with B. gingivalis. The MCM was chromatographed by gel filtration and then assayed for IL-1 activity and for its effect on protein synthesis and alkaline phosphatase (ALP) activity of MC3T3-E1 cells. The activities which were stimulatory for protein synthesis and ALP activity in MC3T3-E1 cells and the IL-1 activity cofractionated in fractions with molecular weight (m. w.) of 10, 000-22, 000. On the other hand, a high molecular weight substance corresponding to a m. w. of about 130, 000 exhibited inhibitory activities for protein synthesis and the ALP activity of MC3T3 -E1 cells. Further, the major peak having the stimulatory and IL-1 activity from gel filtration was sequentially purified by isoelectric focusing.Significant stimulatory activity for DNA and protein synthesis of MC3T3-El cells cofractionated with IL-1 activity at pI 5.8. However, no detectable peak of such stimulatory activities was observed at pI 4.6 while significantly increased IL-1 activity occurred in this fraction. These results suggest the possibility that macrophage-derived factors for osteoblasts may play a regulatory role in bone remondeling in periodontal disease.

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