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ABSTRACT: This is a case report on a solid variant of keratocystic odontogenic tumor arising in the mandible, which aggressively infiltrated into the cancelous spaces and involved the periosteal connective tissue of the mandible. The patient was a 57-year-old woman with an ill-defined radiolucent lesion having a moth-eaten pattern in the left molar region of the mandible. Computed tomography scans revealed that the tumor penetrated the buccal cortical plate of the mandible. Histologically, the lesion was characterized by multicystic spaces lined with a thin layer of keratinizing squamous epithelium, which contained basal cells with palisaded hyperchromatic nuclei. Lumina were filled with concentric layers of parakeratin. An additional feature was the appearance of a conspicuous clear cell component showing intraluminal papillary proliferation or forming small cord-like nests in the fibrous stroma. The patient underwent segmental mandibulectomy followed by reconstruction using a titanium plate. A 20-year follow-up revealed no recurrence of the tumor.
Oral surgery, oral medicine, oral pathology and oral radiology. 05/2013;
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Shinji Kito,
Hirofumi Koga,
Masaaki Kodama,
Manabu Habu,
Shinya Kokuryo,
Noriaki Yamamoto,
Masafumi Oda,
Takanobu Nishino,
Min Zhang, Kou Matsuo, [......],
Daigo Yoshiga,
Takeshi Kaneuji,
Shinnosuke Nogami,
Izumi Yoshioka,
Yoshihiro Yamashita,
Tasturou Tanaka,
Ikuya Miyamoto,
Chiaki Kitamura,
Kazuhiro Tominaga,
Yasuhiro Morimoto
Dentomaxillofacial Radiology 04/2013; · 1.08 Impact Factor
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ABSTRACT: PURPOSE: This study aimed to evaluate the effects of thymosin β4 (TB4) on bone formation. METHODS: A 5mm diameter bone defect was created in the skulls of Wistar rats. Two types of experimental models were prepared: one with atelocollagen sponges used to fill the bone defect and one without. In each experimental model, bone formation in calvarial defects was compared between the group receiving synthetic partial peptides of TB4 intraperitoneally (TB group) and the control group, which received an equivalent amount of phosphate-buffered saline. Calvarial defect sections collected on postoperative days 5, 10, and 20 were analyzed, and the area of newly formed bone was measured. Furthermore, the sections on postoprerative day 5 were immunostained with anti-osterix antibody and the osterix-positive cells were counted. The total RNA extracted from granulation tissue obtained on postoperative day 10 was analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: In both models, with or without atelocollagen sponges, new bone formation was significantly greater in the TB4 group than in the control group. In some TB4 group individuals, the entire bone defect region of diameter 5mm was almost covered with newly formed bone by postoperative day 20. Immunostaining revealed a significant number of osterix-positive cells in the TB4 group. On postoperative day 10, the expression levels of bone-related genes were analyzed by RT-PCR, which showed no statistically significant differences between the two groups. CONCLUSION: The osteogenesis-promoting effects of TB4 observed in critical-sized defects could be of practical use in bone regeneration therapy.
Journal of prosthodontic research. 03/2013;
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Shinji Kito,
Hirofumi Koga,
Masaaki Kodama,
Noriaki Yamamoto,
Shinya Kokuryo,
Manabu Habu, Kou Matsuo,
Takanobu Nishino,
Kohzoh Kubota,
Kosuke Muraoka, [......],
Shinobu Matsumoto-Takeda,
Yuji Seta,
Tatsurou Tanaka,
Ikuya Miyamoto,
Yoshihiro Yamashita,
Chiaki Kitamura,
Keisuke Nakashima,
Tetsu Takahashi,
Kazuhiro Tominaga,
Yasuhiro Morimoto
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ABSTRACT: OBJECTIVES: To elucidate whether fluorine-18-labeled ((18)F) fluoro-2-deoxy-d-glucose (FDG) accumulation can reflect the extent of periodontal inflammation, periapical inflammation, or dental caries. STUDY DESIGN: (18)F-FDG accumulations on positron emission tomography (PET)-computed tomography (CT) were retrospectively compared with the size of the bone resorption areas caused by periodontal inflammation, periapical inflammation, or dental caries on panoramic radiographs, CT, and magnetic resonance imaging (MRI) in 44 subjects. RESULTS: A significant correlation was found between the size of the bone resorption area caused by periodontal (r = 0.595, P < .01) or periapical (r = 0.560, P < .01) inflammation and the highest standardized uptake value (SUVmax) of (18)F-FDG accumulation. A significant correlation was found between the periodontal (r = 0.622, P < .01) or periapical (r = 0.394, P < .01) inflammatory findings on MRI and the SUVmax of (18)F-FDG accumulation. The SUVmax of (18)F-FDG around most teeth with caries was under 1.5. CONCLUSIONS: (18)F-FDG accumulation reflects the extent of dental inflammation, not dental caries.
Oral surgery, oral medicine, oral pathology and oral radiology. 09/2012;
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ABSTRACT: The aim of this study was to evaluate the effects of thymosin β4 (TB4) on wound healing after tooth extraction in rats.
After extraction of the rats' mandibular first molar teeth, a synthetic partial peptide of TB4 was injected intraperitoneally at the time of extraction and every day thereafter for 6 days. Control subjects for the treatment received identical amounts of phosphate-buffered saline solution in the same manner. Histologic analysis, apoptosis assay, and reverse-transcription polymerase chain reaction were performed.
The overall data showed that TB4 treatment suppressed apoptosis and inflammation; it accelerated the process of wound healing, including new bone formation.
The findings demonstrated not only the usefulness of the TB4 partial peptide in wound healing of tooth extraction sockets, but also its potential application for bone regeneration and osteogenesis in bone and bone-related tissues.
Oral surgery, oral medicine, oral pathology and oral radiology. 07/2012; 114(1):17-26.
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Masafumi Oda,
Tatsurou Tanaka,
Shinji Kito,
Shinobu Matsumoto-Takeda,
Kozue Otsuka,
Yuki Hayashi,
Nao Wakasugi-Sato,
Izumi Yoshioka,
Manabu Habu,
Shinya Kokuryo, [......],
Noriaki Yamamoto,
Ayataka Ishikawa,
Min Zhang, Kou Matsuo,
Shunji Shiiba,
Yuji Seta,
Yoshihiro Yamashita,
Tetsu Takahashi,
Kazuhiro Tominaga,
Yasuhiro Morimoto
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ABSTRACT: To evaluate fresh blood imaging (FBI), a magnetic resonance imaging technique that does not use contrast, for identifying hemangiomas and feeding arteries in the oral and maxillofacial regions.
For 16 patients with hemangiomas, FBI visualizations of hemangiomas and feeding arteries in the oral and maxillofacial regions were compared with those from 3-dimensional (3D) phase-contrast magnetic resonance angiography (PC-MRA). Comparisons were based on the conspicuities of blood vessels and the 3D relationships of hemangiomas with the surrounding blood vessels.
The conspicuity of hemangiomas, feeding arteries, and blood vessels were significantly better with FBI than with PC-MRA. After differentiating arteries from veins, 3D visualizations of hemangiomas and arteries or veins could be performed with FBI.
FBI is a useful method in oral and maxillofacial regions for identifying the relationships between hemangiomas and the surrounding arteries or veins.
Oral surgery, oral medicine, oral pathology and oral radiology. 04/2012; 113(4):559-66.
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Hiroyuki Furuta,
Kenji Osawa,
Masashi Shin,
Ayataka Ishikawa, Kou Matsuo,
Masud Khan,
Kazuhiro Aoki,
Keiichi Ohya,
Masato Okamoto,
Kazuhiro Tominaga,
Tetsu Takahashi,
Osamu Nakanishi,
Eijiro Jimi
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ABSTRACT: Nuclear factor-κB (NF-κB) is constitutively activated in many cancers, including oral squamous cell carcinoma (OSCC), and is involved in the invasive characteristics of OSCC, such as growth, antiapoptotic activity and protease production. However, the cellular mechanism underlying NF-κB's promotion of bone invasion by OSCC is unclear. Therefore, we investigated the role of NF-κB in bone invasion by OSCC in vivo. Immunohistochemical staining of OSCC invading bone in 10 patients indicated that the expression and nuclear translocation of p65, a main subunit of NF-κB, was increased in OSCC compared with normal squamous epithelial cells. An active form of p65 phosphorylated at serine 536 was present mainly in the nucleus in not only differentiated tumor cells but also tumor-associated stromal cells and bone-resorbing osteoclasts. We next injected mouse OSCC SCCVII cells into the masseter region of C(3) H/HeN mice. Mice were treated for 3 weeks with a selective NF-κB inhibitor, NBD peptide, which disrupts the association of NF-κB essential modulator (NEMO) with IκB kinases. NBD peptide treatment inhibited TNFα-induced and constitutive NF-κB activation in SCCVII cells in vitro and in vivo, respectively. Treatment with NBD peptide decreased zygoma and mandible destruction by SCCVII cells, reduced number of osteoclasts by inhibiting RANKL expression in osteoblastic cells and SCCVII cells, increased apoptosis and suppressed the proliferation of SCCVII cells. Taken together, our data clearly indicate that inhibition of NF-κB is useful for inhibiting bone invasion by OSCC.
International Journal of Cancer 01/2012; 131(5):E625-35. · 5.44 Impact Factor
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Masafumi Oda,
Tatsurou Tanaka,
Shinji Kito,
Manabu Habu,
Masaaki Kodama,
Shinya Kokuryo,
Ikuya Miyamoto,
Daigo Yoshiga,
Kensuke Yamauchi,
Shinnosuke Nogami, [......],
Ayataka Ishikawa,
Ikuko Nishida,
Katsura Saeki,
Kazumasa Morikawa, Kou Matsuo,
Yuji Seta,
Yoshihiro Yamashita,
Kenshi Maki,
Kazuhiro Tominaga,
Yasuhiro Morimoto
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ABSTRACT: The present paper provides general dentists with an introduction to the clinical applications and significance of magnetic resonance angiography (MRA) in the oral and maxillofacial regions. Specifically, the method and characteristics of MRA are first explained using the relevant MR sequences. Next, clinical applications to the oral and maxillofacial regions, such as identification of hemangiomas and surrounding vessels by MRA, are discussed. Moreover, the clinical significance of MRA for other regions is presented to elucidate future clinical applications of MRA in the oral and maxillofacial regions.
International Journal of Dentistry 01/2012; 2012:865369.
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Tatsurou Tanaka,
Yasuhiro Morimoto,
Shinji Kito,
Ayataka Ishikawa,
Shinya Kokuryo,
Noriaki Yamamoto,
Manabu Habu,
Ikuya Miyamoto,
Masaaki Kodama,
Shinobu Matsumoto-Takeda,
Masafumi Oda,
Nao Wakasugi-Sato,
Kozue Otsuka,
Shunji Shiiba,
Yuji Seta,
Yoshihiro Yamashita,
Izumi Yoshioka, Kou Matsuo,
Tetsu Takahashi,
Kazuhiro Tominaga
11/2011; , ISBN: 978-953-307-723-9
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ABSTRACT: Oral squamous cell carcinomas (OSCCs) are malignant tumors that frequently invade the maxilla and mandibular bone. However, the molecular mechanisms underlying bone invasion by OSCC are unclear. Recent studies showed that receptor activator of nuclear factor κB (RANK) was expressed not only in osteoclast precursors but also in tumor cells. Therefore, we examined whether RANK ligand (RANKL)/RANK signaling regulates bone invasion by OSCC cells in vivo and in vitro. We first injected human OSCC B88 cells into the masseter region of nude mice. Mice were treated for 3 weeks with osteoprotegerin (OPG), the decoy receptor for RANKL. Treatment with OPG decreased bone invasion by B88 cells, reduced the number of osteoclasts and increased B88 cell apoptosis. However, OPG did not affect apoptosis and proliferation in B88 cells in vitro, suggesting that the effects of OPG on apoptosis in B88 cells are restricted in a bone environment. RANK was expressed in the B88 cells and in OSCC cells from patients. RANKL induced NF-κB activation and extracellular signal-regulated kinase phosphorylation in B88 cells and enhanced B88 cell migration in a modified chemotaxis chamber equipped with a gelatin-coated filter. OPG inhibited RANKL-induced NF-κB activation, extracellular signal-regulated kinase phosphorylation and cell migration. Our data clearly indicate that RANKL/RANK inhibition suppresses bone invasion by inhibiting osteoclastogenesis and cancer cell migration and by inducing apoptosis of cancer cells via indirect anticancer action in vivo.
Carcinogenesis 09/2011; 32(11):1634-40. · 5.70 Impact Factor
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Tatsurou Tanaka,
Masafumi Oda,
Shinji Kito,
Nao Wakasugi-Sato,
Shinobu Matsumoto-Takeda,
Kozue Otsuka,
Izumi Yoshioka,
Manabu Habu,
Shinya Kokuryo,
Masaaki Kodama, [......],
Ikuya Miyamoto,
Noriaki Yamamoto,
Ayataka Ishikawa, Kou Matsuo,
Shunji Shiiba,
Yuji Seta,
Yoshihiro Yamashita,
Tetsu Takahashi,
Kazuhiro Tominaga,
Yasuhiro Morimoto
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ABSTRACT: The aim of this study was to evaluate the 3-dimensional images of thinner main peripheral vessels in oral and maxillofacial regions made without contrast medium by using a new technique, fresh blood imaging (FBI). A second objective was to discern arteries from veins by using the combination of FBI with the subtraction technique.
Images from FBI were compared with those from 3-dimensional phase-contrast magnetic resonance angiography (MRA) of blood vessels in 20 healthy subjects. All images were scored for visualization and image quality of the main blood vessels. In addition, appropriate flow-spoiled gradient pulses were applied to differentiate arteries from veins in the peripheral vasculature using a combination of FBI sequences and subtraction between systole- and diastole-triggered images.
The scores of MRA using FBI for the visualization of thin blood vessels were significantly better than those using phase contrast, whereas scores for the visualization of main blood vessels were equal. Additionally, we succeeded in our initial attempt to differentiate arteries from veins with a reasonable acquisition time.
Our initial experience shows that FBI could be a useful method to identify 3-dimensional vasculature and to differentiate arteries from veins among thinner peripheral vessels in the oral and maxillofacial regions without using contrast medium.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 08/2011; 112(4):493-501. · 1.50 Impact Factor
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Noriaki Yamamoto,
Yoshihiro Yamashita,
Tatsurou Tanaka,
Ayataka Ishikawa,
Shinji Kito,
Nao Wakasugi-Sato,
Shinobu Matsumoto-Takeda,
Masafumi Oda,
Ikuya Miyamoto,
Kensuke Yamauchi,
Shunji Shiiba,
Yuji Seta, Kou Matsuo,
Hirofumi Koga,
Tetsu Takahashi,
Yasuhiro Morimoto
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ABSTRACT: To elucidate the clinical significance of imaging modalities for detection of stitch abscess after surgery in patients with oral squamous cell carcinoma (SCC). In 137 patients with oral SCC suspected of having lymph node metastases, local recurrence of tumor, or stitch abscess after surgery, the characteristic imaging findings related to lymph node metastases, local recurrence of tumor, and stitch abscess on ultrasonography (US), computed tomography (CT), magnetic resonance (MR), and (18)fluorodeoxyglucose (18FDG)-positron emission tomography (PET) images were identified and analyzed. In all six patients with stitch abscess, characteristic findings were demonstrated on US, different from those of metastatic lymph nodes and local recurrence on CT, MRI, and 18FDG-PET images. Our results suggest that ultrasonography may be a very useful tool for diagnosis of postoperative stitch abscess and may help improve the quality of life of oral SCC patients.
Oral Oncology 11/2010; 47(3):163-9. · 2.86 Impact Factor
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Nao Wakasugi-Sato,
Tetsuro Wakasugi,
Masafumi Oda,
Yoshihiro Yamashita,
Izumi Yoshioka,
Noriaki Yamamoto,
Manabu Habu,
Masaaki Kodama,
Shinya Kokuryo,
Hisashi Ichimiya,
Ikuya Miyamoto,
Tatsurou Tanaka,
Shinji Kito,
Shinobu Matsumoto-Takeda,
Ayataka Ishikawa,
Yuji Seta, Kou Matsuo,
Tetsu Takahashi,
Kazuhiro Tominaga,
Yasuhiro Morimoto
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ABSTRACT: The objective of this study was to evaluate the clinical significance of ultrasonography (US) for screening for thyroid gland diseases when surveying the cervical lymph nodes to detect metastasis in subjects with oral squamous cell carcinoma (SCC).
The detection rates and characteristics of abnormal thyroid findings detected by US in 301 subjects with oral SCC were analyzed. Subjects with abnormal findings were referred to thyroid specialists and the diagnoses and treatments from these specialists were noted. The ratio of subjects who consulted a thyroid specialist after indications of thyroid gland abnormalities to analyze subject compliance was also examined. Follow-up examinations were regularly conducted to assess any changes in the thyroid gland.
Of the 301 subjects with oral SCC, 91 had abnormal thyroid gland findings on US. As subject age increased, the rate of detection of abnormal thyroid gland findings on US significantly increased. The rate of detection of abnormal findings in women by US was significantly higher than that in men, but the male-to-female ratio was lower compared with that in previous reports. It was demonstrated that oral SCC in the floor of the mouth was associated with the highest prevalence of abnormal findings in the thyroid gland (40%), followed by oral SCC of the maxillary gingiva (39%). Of the 91 subjects with abnormal findings, 10 showed enlargement in the size of the lesion on follow-up examination with US. Eleven subjects with no abnormal findings on initial examination showed abnormal findings on follow-up examination.
The results suggest that subjects with oral SCC have a relatively high rate of abnormal findings in the thyroid gland that can be detected by US. Scans that include the thyroid gland should be performed when surveying cervical lymph nodes for metastasis during US examination. Particular attention should be paid to thyroid gland-related diseases in older men who have oral cancer and to thyroid gland abnormalities if patients had oral SCC in the floor of the mouth or of the maxillary gingiva. It is recommended that follow-up US examinations be regularly performed in cases of oral SCC.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 06/2010; 109(6):e78-85. · 1.50 Impact Factor
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Nao Wakasugi-Sato,
Masaaki Kodama, Kou Matsuo,
Noriaki Yamamoto,
Masafumi Oda,
Ayataka Ishikawa,
Tatsurou Tanaka,
Yuji Seta,
Manabu Habu,
Shinya Kokuryo,
Hisashi Ichimiya,
Ikuya Miyamoto,
Shinji Kito,
Shinobu Matsumoto-Takeda,
Tetsuro Wakasugi,
Yoshihiro Yamashita,
Izumi Yoshioka,
Tetsu Takahashi,
Kazuhiro Tominaga,
Yasuhiro Morimoto
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ABSTRACT: Various kinds of diseases may be found in the oral and maxillofacial regions and various modalities may be applied for their diagnosis, including intra-oral radiography, panoramic radiography, ultrasonography, computed tomography, magnetic resonance imaging, and nuclear medicine methods such as positron emission tomography. Of these modalities, ultrasound imaging is easy to use for the detection of noninvasive and soft tissue-related diseases. Doppler ultrasound images taken in the B-mode can provide vascular information associated with the morphology of soft tissues. Thus, ultrasound imaging plays an important role in confirming the diagnosis of many kinds of diseases in such oral and maxillofacial regions as the tongue, lymph nodes, salivary glands, and masticatory muscles. In the present article, we introduce three new applications of ultrasonography: guided fine-needle aspiration, measurement of tongue cancer thickness, and diagnosis of metastasis to cervical lymph nodes.
International Journal of Dentistry 01/2010; 2010:639382.
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ABSTRACT: It is important to develop a suitable three-dimensional scaffold for the regeneration therapy of dental pulp. In the present study, the effects of hyaluronic acid (HA) sponge on responses of the odontoblastic cell line (KN-3 cells) in vitro, as well as responses of amputated dental pulp of rat molar in vivo, were examined. In vitro, KN-3 cells adhered to the stable structure of HA sponge and that of collagen sponge. In vivo, dental pulp proliferation and vessel invasion were observed in both sponges implanted at dentin defect area above amputated dental pulp, and the cell-rich reorganizing tissue was observed in the dentin defect when HA sponge was implanted as compared with collagen sponge. Expression levels of IL-6 and TNF-alpha in KN-3 cells seeded in HA sponge were nearly the same with those in the cells seeded in collagen sponge, while the numbers (0.67 x 10(3) at 1 week and 0.7 x 10(3) at 3 weeks) of granulated leukocytes that invaded into HA sponge from amputated dental pulp was significantly lower than those (1.22 x 10(3) at 1 week and 1.1 x 10(3) at 3 weeks) of collagen sponge (p < 0.01 at 1 week and p < 0.05 at 3 weeks). These results suggest that HA sponge has an appropriate structure, biocompatibility, and biodegradation for use as a scaffold for dental pulp regeneration.
Journal of Biomedical Materials Research Part B Applied Biomaterials 10/2009; 92(1):120-8. · 2.15 Impact Factor
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ABSTRACT: Immunohistochemical and ultrastructural findings in a rare case of papillary cystadenocarcinoma arising from the left sublingual gland of a 55-year-old Japanese man are reported. Histologically, the tumor tissue was found to be composed of various-sized cystic cavities in which papillary epithelial projections with thin fibrovascular cores were observed. The papillary projections consisted of a single layer to several layers of high columnar epithelial cells. Invasion to the surrounding fibrous tissue and into the lymphatics was observed, thus suggesting an aggressive potential in the present case. The possibility of the involvement of myoepithelial cells could be excluded based on the immunohistochemical and ultrastructural findings. The immunohistochemical and ultrastructural findings also suggested that this type of salivary gland tumor, at least the present case, may arise from striated or excretory ducts. There was positive immunostaining for tumor markers CA19-9 and CA125. However, the biological role of these carbohydrate antigens in salivary gland tumors is unclear at present. Further investigations are, therefore, called for to solve this issue.
Journal of Oral Pathology and Medicine 02/2007; 28(6):282 - 286. · 1.63 Impact Factor
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ABSTRACT: Runx2/Cbfa1 is an essential transcription factor for osteoblast differentiation and bone formation. Runx2/Cbfa1 knockout mice showed both a complete lack of ossification and the developmental arrest of tooth germ. We here report Runx2/Cbfa1 isoform-type specific functional roles in the development of tooth germ by the administration of antisense phosphorothioate oligodioxynucleotides (S-ODNs) into cultured mouse mandibles. The administration of type II/III Runx2/Cbfa1 antisense S-ODNs into the culture media resulted in an arrest of tooth germ growth at the bud-like stage in cultured mandible taken from the 11-day-old embryos, while also causing the inhibition of the differentiation of odontogenic cells into ameloblast and odontoblast in cultured tooth germs taken from the 15-day-old embryos. The expression of dentin matrix protein 1, dentin sialophosphoprotein, amelogenin, and ameloblastin was shown to be markedly suppressed in cultured tooth germ by the semi-quantitative RT-PCR. Meanwhile, no developmental arrest of tooth germ, no inhibition of gene expression, or differentiation of odontogenic cells was observed in samples treated with the type I Runx2/Cbfa1 antisense S-ODNs. The same findings were also observed in either the control or the sense and random sequence S-ODNs-treated samples. These data indicate that the type II/III Runx2/Cbfa1 isoform is closely related to the development and differentiation of tooth germ.
Bone 07/2006; 38(6):836-44. · 4.02 Impact Factor
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ABSTRACT: We examined the detailed in situ expression pattern of thymosin beta 4 (Tbeta4) in the developing mouse mandibular first molar. Tbeta4 mRNA was expressed in the presumptive dental epithelium at embryonic day 10.5 (E10.5) and in the thickened dental epithelium at E12. An in situ signal was observed in the invaginated epithelial bud at E13, in the enamel organ at E14 and E14.5, and in the primary enamel knot (PEK) at E14.5. The signal was localized in the epithelial cells of the outer layer of the enamel organ at E15 and E15.5. No signal was found in the PEK at these stages. Tbeta4 mRNA was expressed in the inner enamel epithelium, cervical loop and dental lamina at E16 and E17. The expression of Tbeta4 mRNA was observed in the polarized inner epithelial cells at E18, newborn day 1 (N1) and N2. However, the signal intensity decreased markedly at N3. We herein report for the first time that Tbeta4 is distinctly expressed in developing tooth germ, and it may also play functional roles in the initiation, growth and differentiation of tooth germ.
Histochemie 10/2005; 124(3-4):207-13. · 2.59 Impact Factor
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ABSTRACT: owing that the apoptosis occurring in the developing odontogenic tissue was induced by the activation of the caspase family. The specific distribution pattern of apoptotic cells in the developing odontogenic epithelial tissue from the initiation (E12) of tooth germ to the completion of tooth crown morphology (E19) also suggests that apoptotic events are related not only to a deletion of functionally suspended cells, but also participate in initiation and the completion of tooth morphogenesis. Electron microscopic examination revealed that apoptotic cells were present in the primary enamel knot, and these apoptotic cells were phagocytized by neighbouring odontogenic epithelial cells, thus indicating the prompt disposal of any dead cells by epithelial cells. Introduction The developing tooth is known to be a suitable model for studying the molecular mechanism of epithelial-- mesenchymal interactions regulating the morphogenesis of many organs and tissues. Cell death is
09/2001;
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ABSTRACT: The detailed in situ expression pattern of the Set- gene has been studied. Previously we showed that Set- is a differentially expressed gene in the embryonic mouse mandible at day 10.5 (E10.5) gestational age. Cells expressing Set- were widely distributed in both the epithelial and underlying ectomesenchymal cells at E10.5. At E12, they were slightly aggregated in an area where tooth germ of the lower first molar is estimated to be formed. At E13.5, Set- was strongly expressed in the tooth germ. At the cap stage, Set- was expressed in the enamel organ and dental papilla. At the bell stage, Set- was distinctly expressed in the inner enamel epithelial and dental papilla cells facing the inner enamel epithelial layer, which were intended to differentiate into ameloblasts and odontoblasts, respectively. Interestingly, Set- was also expressed in several embryonic craniofacial tissues derived from the ectoderm. This study is the first report that Set- is distinctly expressed in the developing tooth germ, and suggests that Set- plays an important role in both the initiation and the growth of the tooth germ, as well as in the differentiation of ameloblasts and odontoblasts.
The Histochemical Journal 07/2001; 33(8):437-441.
