We examined sixty-three human embryos ranged from three weeks to eight weeks of fertilization age and 117 human fetuses from eleven weeks to fourty weeks of gestational age. Anatomical structure of developing tongue could be classified into eight developmental stages. The first is the sgage of mesial swelling of tongue primordium in the fertilization age of 28~40 days (Streeter stage 13~16), the second is the stage of lateral swelling of tongue primordium in the fertilization age of 41~46 days (Streeter stage 17~18), the third is the sgage of vertical positioning of tongue in the fertilization age of 47~53 days (Streeter stage 19~21), the fourth is the transitional stage of tongue from vertical position to horizontal position in the fertilization age of 54~56 days (Streeter stage 22~23), the fifth is the stage horizontal positioning of tongue in the gestational age of 11 weeks, the sixth is the stage of protrusion of tongue in the gestational age of 12 weeks, the seventh is the stage of maturation of tongue muscle in the gestational age of 7-10 months. The development of tongue papilla characteristically progresses into three stages. The first stage is the epithelial ingrowth for the crypt formation, the second stage is the anatomical formation of vallate, fungiform and filiform papillae, and the third stage is the differentiation of taste buds in the vallate and fungiform papillae or the formation of thick spike-like keratinization at the tip of filiform papilla. We observed that the tongue primordium mainly derived from occipital myotome developed more repidly than other oro-facial structures, so it transitionally occuied the spaces of the pharynx and the posterior nasal cavity, and directly affected the formation of palate and the growth of maxilla and mandible. Whereas the tongue papilla development showed continuous developmental sequences during the fetal period.
Humans

Five fetal maxillas were obtained from the autopsy file of fetal postmortem examination, and were examined by serial micro-sections of frontal plane and horizontal plane. Especially the area around the incisive canal of the maxilla was carefully observed. The results are as follows. 1) In 5 fetal maxillas extra-dental laminas and supernumerary tooth germs which are severely malformed in shape are found in the dilated incisive canal, where prominent vessels and nerves are distributed. 2) The supernumerary tooth germs disclose almost normal histo-differentiation of odontoblast and ameloblast, and there shows relatively abundant perifollicular fibrosis in the place of perifollicular bone. 3) It is observed that the over-growth of the extradental lamina from the dental ridge of deciduous central incisor frequently tends to direct toward the incisive canal that includes prominent vessels and nerves.

In order to elucidate the developmental stages of human tooth germ during prenatal period, we examined 254 normal fetuses ranging in gestational age from six weeks to fourty weeks old histologically. Lim's developmental pattern of prenatal tooth germ was divided into three groups, the first group consisting of five grades (I, II, III, IV, V) was for the development of enamel epithelium the second group of three grades was for the deposition of dentin matrix and enamel matrix, and the third group of three grades (A, B, C) was for the growth of perifollicular bone. Some developmental progress between enamel epithelium and dental papilla could be identified by observation of the sequential development of deciduous and permanent tooth germs histologically. The following results were made. 1) The prenatal development of tooth germ showed similar weekly stages in both the maxilla and the mandible. The initial deposition of dentin matrix and enamel matrix (III-1 stage) started at 12-14 weeks of gestational age in the deciduous incisor and canine, and at 16-20 weeks of gestational age in the deciduous molars. And the initial deposition of dentin matrix and enamel matrix in the permanent first molar was at 20-22 weeks of gestational age, and that of the permanent incisor was at 34-36 weeks, and that of the permanent canine was 36-38 weeks, and of the permanent premolar was at 38-40 weeks. 2) The S-shaped curvature was characteristically found where the reciprocal induction of odontoblast and amelobast occurred actively in the developing tooth germ. Primarily pre-ameloblasts which abutted on the dental papilla differentiate the condensed mesenchymal cells into odontoblasts, and secondarily matured odontoblasts which bulged into enamel epithelium produced dentin matrix and differentiated the shrunken pre-ameloblasts into ameloblasts. 3) The mandible grew more rapidly than the maxilla during the early prenatal period. The trabecular bone from both jaws proliferated initially into labial side of developing tooth follicle and gradually circumscribed the tooth follicle lingually and mesio-distally, to form perifollicular bone resultantly.
Humans

No abstract available.
Ameloblastoma* ; Biopsy, Fine-Needle*

BACKGROUND: Up to now, sleep stages have traditionally been determined by the visual inspection of individual EEG waves. However, the exact physiological meaning of the sleep waves is not known. The purpose of this study was to try and find out the physiological parameters of the EEG of the sleep and wakefulness states by calculating one of the non-linear chaos parameter, the largest Lyapunov exponent (LLE), of EEG time series. METHODS: The digital EEG of the wakefulness with eye opening (WEO), wakefulness with eye closure (WEC), stage1 (S1), stage2 (S2), stage3 or 4 (S34) were recorded at centroparietal region (C4-P4 bipolar derivation) in 10 normal subjects. Lyapunov exponents of 50 EEG time series in different states were compared. RESULTS: LLE's of WEO, WEC, S1, S2, S34 showed an increas-ing tendency as states switched from wakefulness to sleep. LLE of sleep was larger than that of awake state. CONCLUSIONS: The EEG of the sleep state appeared to be more chaotic than that of the awake state. This nonlinear chaos parameter can be used as a physiological parameter of normal sleep and awake states.
Electroencephalography* ; Sleep Stages ; Wakefulness*

OBJECTIVES: The aim of this study is to evaluate radiation exposure resulting from the comprehensive health examinations of selected university hospital programs and to present basic data for research and management strategies on the health effects of medical radiation exposure. METHODS: Radiation-based diagnostic studies of the comprehensive health examination programs of ten university hospitals in Seoul, Korea, as introduced in their websites, were analyzed. The medical radiation studies of the programs were reviewed by radiologists. Only the effective doses of the basic studies were included in the analysis. The optional studies of the programs were excluded. RESULTS: Among the 190 comprehensive health examination programs, 132 programs (69.5%) included computed tomography studies, with an average of 1.4 scans. The average effective dose of radiation by program was 3.62 mSv for an intensive program for specific diseases; 11.12 mSv for an intensive program for cancer; 18.14 mSv for a premium program; and 24.08 mSv for an overnight program. A higher cost of a programs was linked to a higher effective dose (r=0.812). The effective doses of the examination programs for the same purposes differed by as much as 2.1 times by hospital. Inclusion of positron emission tomography–computed tomography was the most critical factor in determining the level of effective dose. CONCLUSIONS: It was found that radiation exposure dose from comprehensive health exam programs targeted for an asymptomatic, healthy public reached between 3.6 and 24 times the annual dose limit for the general public. Relevant management policies at the national level should be provided to minimize medical radiation exposure.
Electrons ; Hospitals, University ; Korea* ; Mass Screening* ; Radiation Exposure ; Seoul

No abstract available.

No abstract available.
Blindness* ; Orbit*

No abstract available.
Pancreatic Neoplasms

No abstract available.
Mandibular Fractures ; Osteomyelitis ; Transplants