Development of Model System for Radiation Induced Congenital Malformations by Whole Embryo Culture / 체질인류학회지

It is known that radiation can induce various kind of mutations, cancers and congenital malformations. Day 9 rats embryos were cultured by whole embryo culture method and irradiated 0.1, 0.5, 2 and 5 Gy at day 10 to study the effect of radiation on the development of rat embryos. Haversting after 48 hours culture, the morphological changes and apoptosis were investigated. In addition, we assessed the expression patterns of p53, WAF1, Bcl -2, Bcl -x and Bax. Compared to the control group, no remarkable morphological changes were observed in the low dosage group (0.1 and 0.5 Gy). But at high dosage group (2 and 5 Gy), growth was retarded and the heart beats were weak. The crown rump length, the number of somites, and branchial arch were decreased and the rotation of embryo and development of otic pit and lens pit, and upper limb bud was delayed significantly. Especially in the 5 Gy group the most of external morphology were difficult to discriminate. In histological observations, high dosage group showed marked increase in the number of apoptotic bodies in the optic cup, trigeminal ganglion, pharyngeal arches, heart and small intestine. In western blot analysis, Bcl -x and Bax were not expressed in all groups. Expression level of Bcl -2 was constant regardless of the amount of radiation. Expression level of p53 and WAF1 increased significantly in accordance with the increasing amount of radiation. Especially, WAF1 was expressed 7.2, 6.3, 9.9 and 11.3 folds more than the control groups when embryos were exposed to 0.1, 0.5, 2 and 5 Gy, respectively. Considering WAF1 arrests cell cycle, we concluded that cell cycle was affected most sensitively to radiation injury. From these results, radiation showed growth retardation, decrease in protein synthesis, increase in apoptosis and expression of related genetic materials. These results may be used as a standard to test the effect of drugs for reducing and protecting agents against deterious effect of radiation in developing embryo and fetus.

Development of the lip and palate in staged human embryos and early fetuses

Cleft lip and palate are the most common congenital malformations in humans. Using 43 staged human embryos and early fetuses ranging from the 4th to 12th week of development, we investigated the development of the lip and palate in order to provide the basic developmental concepts required for managing these anomalies. The lower lip appeared as bilateral mandibular arches at Carnegie stage 11, and these were completely merged at stage 15. The components of the upper lip, medial nasal prominence and maxillary process, appeared at stage 16, and completely merged at stage 20. The median palatine process appeared at stage 16, and the lateral palatine process, at stage 17. The palatine processes and the nasal septum started to fuse abruptly at stage 23, and from external observation seemed to be fused at the 9th week. However, complete fusion did not take place until the 12th week of development. The tongue was prominent at stage 16, showed differentiation of the muscular tissue at stage 21, and was located superior to the lateral palatine process before stage 23. These results may be used in understanding the different mechanisms present in the formation of various congenital anomalies in this region.

Apoptosis induced by changes in the temperature during whole embryo culture of postimplantation rat embryos / 대한해부학회지

It has been reported that heat shock (43degrees C) induces an episode of cell death in developing central nervous system as part of pathogenesis leading to abnormal growth and development. Cell death induced by heat shock is likely to occur by a process termed apoptosis. On the other hand, protective role of mild heat shock on heat shock-induced apoptosis has also been suggested. In this study, the effect of 43degrees C heat shock on the induction of apoptosis was investigated in detail firstly by determining internucleosomal DNA fragmentation (DNA laddering) and secondly by determining apoptotic bodies using TUNEL (TdT-mediated dUTP-biotin nick end labeling). In addition, the effect of mild heat shock (42degrees C) on the apoptotic process was examined. In order to modulate the environmental temperatures of the developing embryos, we used whole embryo culture technique. DNA fragmentation and apoptotic body was induced a little by 42degrees C exposure but embryos exposed to 43degrees C showed strong DNA fragmentations. In comparison, the amount of DNA fragmentation was significantly reduced in embryos with 42degrees C pretreatment than 43degrees C group. In the control embryos (37degrees C exposure), basal levels of DNA fragmentation and apoptotic bodies were observed. From this study, it was evident that thermotolerance could protect the early postimplantation embryos from hyperthermia.

DEVELOPMENT OF NERVES IN THE UPPER LIMB OF HUMAN EMBRYOS

No abstract available.