The Effect of Prophylactic Central Neck Dissection During Hemithyroidectomy on Locoregional Recurrence in Patients With Papillary Thyroid Carcinoma: A Meta-Analysis

Objectives@#. Hemithyroidectomy is commonly performed in patients with low- to intermediate-risk papillary thyroid carcinoma. The purpose of this meta-analysis was to evaluate the effect of prophylactic central neck dissection on locoregional recurrence in patients undergoing hemithyroidectomy. @*Methods@#. A meta-analysis was performed of full-text publications published in English retrieved from the Embase database. @*Results@#. The rate of regional recurrence in the central compartment after hemithyroidectomy, with or without prophylactic central neck dissection, was 0.17% and 1.78%, respectively. This difference was statistically significant. Recurrence in the lateral compartment or contralateral thyroid was not affected by prophylactic central neck dissection; the overall rate of recurrence was 1.3% and 5.4%, respectively. @*Conclusion@#. Prophylactic central neck dissection significantly reduced the risk of recurrence in the central compartment in patients undergoing hemithyroidectomy.

Current Anatomical Cadaver Dissection and the Limitation of the Act of Corpse Dissection and Preservation / 체질인류학회지

The Act of Corpse Dissection and Preservation is the prime law related with anatomical cadaver dissection in Korea. Consider the social and cultural situation at the year of 1995 when the law established, it has much epochal contents. Now, however, it has many regulations, such as the purpose of establishment the law, object of dissection, management of cadaver after dissection, and the lack of body donation movement, which are not coincide with current anatomical dissection field. In order to supplement such insufficiencies, it is necessary to revise the Act of Corpse Dissection and Preservation as soon as possible. Furthermore, it is recommended to establish a new law supporting the body donation movement and management for activation of anatomical dissection education, which eventually extend the basis of the development of medical science.

A Case of Transoral Robotic Radical Lateral Oropharyngectomy in Tonsilar Cancer / 대한이비인후과학회지

Transoral robotic system (TORS) is performed by positioning at least 3 robotic arms through the oral cavity that are operated by the surgeon bimanually. The elaborate movements of the operating tools and high resolution endoscopic images provided by the robot can overcome the shortcomings of transoral radical lateral oropharyngectomy, thus enabling wide and effective surgery. Also, it preserves postoperative functions and improves the quality of life, thereby decreasing postoperative morbidity. In this study, the possibility of TORS as a novel surgical method in managing tonsillar carcinoma has been identified. However, a long term observation regardingpostoperative swallowing, phonation, quality of life and oncologic safety in using TORS is further required.

The Type of Handedness and Correlation Analysis of Handedness Assessment Items on University Students in Korea / 체질인류학회지

The left handers are different from the right handers in brain development aspects and various perceptive or cognitive performance. There are known the types of handedness are under social and cultural influence. Moreover, the different races or countries show the different sensitivity to each item in assessment tool. The aim of the this study is to assess type of handedness and choose the best item of assessment tool for Korean. The subjects of this study were 1,063 persons. Data were collected by total 31 items including 20 items through reconstruction of the Oldfield Test, Annett Questionnaire and Croviz-Zener Questionnaire. The reliability of tool is Cronbach's alpha=0.948. The data were analyzed through frequency, reliability analysis, t-test, and Pearson's Correlation analysis by SPSS win 14.0. The 11.5% of total subjects was changed handedness through experience, 62.7% of these subjects changed from left handedness to right or mixed handedness, and 30.5% of these subjects changed handedness from sixth years old or more to below eighth years old. The mean of handedness score between parents and offspring revealed statistically significant difference (father and offspring t=-5.227, p<0.001, mother and offspring t=-4.515, p<0.001). The left handedness increased from the past ratio 4.8% (Kang 1994) to the present study 6.0% (64 persons) by handedness assessment tool. The mean of total items showed significant positive correlations with hammering a nail (r=0.892, p<0.001), gripping knife (r=0.871), using scissors (r=0.847), and writing exhibited the lowest correlation (r=0.563). These results demonstrate that left handers in Korea were increased than the results by previous researchers, and the best items for distinguishing the left handers from the right handers were the hand hammering a nail, gripping knife, using scissors, lighting a match, and throwing small ball.

An Immunohistochemical Study on the Macrophages in the Developing Corpora Lutea of the Rat / 대한해부학회지

Within the corpus luteum, macrophages exert luteotropic and luteolytic actions through secretion of TNF-alpha. However, the mechanisms of luteotropic actions on the development and maintenance of pregnant and nonpregnant corpora lutea are thoroughly unknown.In this experiment, TUNEL, macrophage, and TNF-alpha immunohistochemistry on the corpora lutea of pregnant and nonpregnant rats (Sprague-Dawley strain) were carried out to reveal the role of macrophages in the developing corpora lutea. The results were as follows; 1) In the nonpregnant corpora lutea, the number of macrophages was increased significantly, and the degree of ED1-immunoreactivity of macrophages was increased moderately. But lutein cells showed low-degree TNF-alpha-immunoreactivity. 2) In the pregnant corpora lutea, the number of macrophages was decreased significantly, and the degree of ED1- immunoreactivity of macrophages was low. But lutein cells showed moderate-degree TNF-alpha-immunoreactivity. Based on the above results, it was considered that macrophages in the nonpregnant corpora lutea exert phagocytic action mainly, and the macrophages in the pregnant corpora lutea exert TNF-alpha-secreting action to maintain the structure and function of lutein cells.

Low-dose Radiation-induced Hormetic Effect in the Rat Ovarian Follicle / 체질인류학회지

Hormesis is the generally-favorable biological responses to low exposures to toxins and other stressors. Radiation hormesis is the theory that ionizing radiation is benign at low levels of exposure, and that doses at the level of natural background radiation can be beneficial. The purpose of this study is to reveal the hormetic effect of low-dose radiation of ionizing radiation on the ovarian follicles of 4-week old female mice. Mice were grouped into control group, 2 cGy irradiated group, 2 cGy and 2 Gy irradiated group (2 cGY pre-exposure group), and 2 Gy irradited group. Mice were sacrificed by cervical dislocation 24 hours after irradiation, removed ovaries, fixed in neutral formaldehyde solution for 24 hours, embedded with paraffin, stained with hematoxylin and eosin and TUNEL immunohistochemically, and observed light microscopically the atretic follicles and normal follicles in various follicular developmental stages. In this experiment, the ratrio of atretic follicles to entire follicles in an ovary increased significantly in 2 Gyirradiated group compared with 2 cGY pre-exposure group, and the ratio of normal follicles to the entire follicles in an ovary in all the developmental stages were increased significantly in the 2 cGY pre-exposure group compared with 2 Gy-irradiated group. These results mean that low-dose radiation pre-exposure can induce the hormetic effect in the developing ovarian follicle.

Changes of Apoptosis After X-irradiation During the Hindlimb Development in the Rat Fetus / 체질인류학회지

Ionizing radiation exerts harmful effect during the limb development, but the exact mechanism is still largely unknown. In this study, 2 Gy of X-ray irradiated to the rat fetuses on gestation day of 13.7 when the hindlimb buds appear, and sacrificed at GD 14.7, GD 15.7 and GD 16.7, respectively. To reveal the changes of apoptotic figures between control and experimental groups, TUNEL immunohistochemistry and confocal laser scanning microscopy were carried. Mean body weight of fetuses of irradiated groups were decreased significantly compared to the control group. Numerical digit anomalies and asymmetries between right and left sides were increased significantly in the irradiated group compared to control group. Some digit anomalies were increased significantly in the right side. Radiation-induced decrement of the density of apoptotic figures on GD 14.7 was presumed to be related with foot and digit anomalies.

Left Minor Fissures of the Lungs in Korean / 체질인류학회지

Accessory fissures serve not only as natural barriers against infection but also help in localizing any focal pulmonary parenchymal diseases and in distinguishing pleural from parenchymal diseases. Knowledge of these fissures might be useful in differentiating unusual forms of atelectasis or consolidation occuring adjacent to the fissure. Left minor fissure (LMF) is a kind of unusual accessory fissures of the left lung, which separates adjacent segments of the upper lobe as clefts of various depths lined by two layers of visceral pleura. In this study, 4 cases of LMFs found in the left upper lobe during a routine dissection of 36 cadavers were observed. Of the 4 cases, 3 cases were true LMFs which located between the anterior segment of the upper lobe and superior segment of lingula, and 1 case was considered as left azygos fissure. Among the true LMFs, 2 LMFs coursed horizontally and 1 LMF coursed upward obliquely along the costal surface. The depth of LMFs was 0.5~1.2 cm and the length was 5~8 cm.

TNFalpha and TNFR2 Immunohistochemistry During Ovarian Follicular Development and Atresia in the Rat / 대한해부학회지

Tumor necrosis factor alpha (TNFalpha) is an intraovarian cytokine that may play a role in ovarian development and function. Identification of ovarian TNFalpha receptors provides support for establishing a role of TNFalpha in ovarian development and function. TNFalpha exerts its effects by binding to either TNF receptor 1 or 2 (TNFR1 or TNFR2). When TNFalpha binds with TNFR2, expression of survival genes is up-regulated, resulting in proliferation of granulosa cells. In the present study, the authors identified the changes in localization of TNFalpha and the expression of TNFR2 in granulosa cells during follicular atresia in rat ovaries. In healthy follicles, intense signals for TNFalpha and TNFR2 were found in the outer surface of the granulosa layer, where many proliferating cells and no apoptotic cells were observed. In atretic follicles, decreased expression of TNFalpha and TNFR2 was observed in the granulosa layer, where many apoptotic cells were seen. These findings suggested that TNFalpha acts as a survival factor in granulosa cells during follicular atresia in rat ovaries.

Distribution and Role of Ovarian Follicle Macrophage in Rat Ovarian Follicular Atresia / 대한산부인과학회지

OBJECTIVE: Ovarian follicular atresia is initiated from ovarian granulosa cell apoptosis and macrophages exert their effects directly and/or indirectly on follicular atresia by phagocytosis of apoptotic bodies and secretion of various cytokines. In spite of the abundant data on ovarian macrophages, the presence of these cells within the follicles (i.e., among granulosa cells) remains controversial and the elimination methods of apoptotic bodies of atretic follicles, and the time and methods of penetration of macrophages into the follicles are not known completely. The aim of the present study is to demonstrate the presence of macrophage within the ovary as related to follicular atresia and the process of elimination of apoptotic granulosa cells by light and electron microscopy. METHODS: Using rat ovaries, immunohistochemical studies with rat macrophage monoclonal antibody ED1 for macrophages, and light and transmission electron microscopic observations were performed. RESULTS: In the rat, follicular atresia was initiated by the granulosa cell apoptosis which occured randomly within the all granulosa layers. Macrophages were observed within normal follicles, in antrum, granulosa and theca cell layers of atretic follicels, in interstium and in corpus luteum. Ultrastructurally, apoptotic granulosa cells showed characteristics, pyknotic nucleus and apoptotic body formation. Apoptotic bodies were eliminated by intact neighboring granulosa cells and macrophages. Intact granulosa cells ingested apoptotic bodies transiently, soon after they fell into the apoptosis. Finally, apoptotic bodies and degenerating oocytes were phagocytosed by macrophages. Macrophages entered the ovarian follicle at the time of initiation of granulosa cell apoptosis, and migrated with the progression of apoptosis. By elimination of theca cells, macrophages contributed the completion of follicular atresia. CONCLUSION: This study demonstrates both intact neighboring granulosa cells and macrophages in the elimination of apoptotic bodies in atretic follicles of the rat ovary. Macrophages are present within normal follicles, in atretic follicles such as antrum, granulosa and theca cell layers and in corpus luteum but are in different appearances according to their location in ovary. A number of macrophages appearing in atretic follicles and in corpora lutea suggest a role for macrophages in follicular atresia and corpus luteum differentiation. The function of macrophage according to their location in follicular development should be further studied.

Changes of Macrophages in Rat Corpus Luteum: Immunohistochemical and Transmission Electron Microscopy Studies / 대한산부인과학회지

OBJECTIVE: The purpose of this study is to assess morphologically the changes of macrophages during various developmental periods of the corpus luteum in the rat ovary. METHODS: The female rats (Sprague-Dawley strain) at age 8 weeks, ovulatory period; 6 days of gestation, early pregnancy period; 19 days of gestation, late pregnancy period; and postpartum 5 days, postpartum period were used. Removed ovaries were dissected and used for TdT-mediated dUTP biotin nick end labelling (TUNEL), macrophages immunohistochemistry, and Transmission Electron Microscopy (TEM). RESULTS: Macrophages were observed in all the developmental periods. The number of apoptotic bodies and macrophages was highest at the ovulatory period, and decreased at postpartum period, early pregnancy period and late pregnancy period in order. The immunoreactivity of macrophages was high at ovulatory period, moderate at late pregnacy and postpartum period, and low at early pregnancy period. In TEM observations, two types of macrophages were observed. One was non-phagocytic macrophage which has slender cell body and long cytoplasmic processes and contained no apoptotic bodies, and the other was phagocytic macrophage which contained apoptotic bodies, phagocytic vacuoles and many lipid droplets and located near the capillaries. CONCLUSION: In the rat corpus luteum, the number and the degree of immunoreactivity of macrophages changed according to the functional developmental periods of the corpus luteum. The functions of the macrophages were suggested as the elimination of apoptotic bodies at the ovulatory and postpartum periods, and luteotropic action at the early and late pregnancy periods. Ultrastructurally, two types of macrophages, phagocytic and non-phagocytic, were confirmed.

Follicular Atresia and Macrophages in the Porcine Ovary; Immunohistochemical and Transmission Electron Microscopic Study / 대한해부학회지

Apoptosis of granulosa cells leads follicular atresia and macrophages have an important role during the apoptotic process. However, the propagation of apoptosis within the follicle, the ways of elimination of apoptotic bodies and degenerated oocyte, and the completion of follicular atresia are still controversial and unidentified clearly. Using adult porcine (Yorkshire-breed) ovary, in this morphological study, transmission electron microscopic observation and immunohistochemical study with pig macrophage monoclonal antibody 4E9 were performed. In light microscopy, the follicular atresia initiated with apoptosis of granulosa cells, followed by degeneration of oocyte and apoptosis of theca interna cells. Apoptosis occured in random fashion among the granulosa cells and propagated multidirectionally, and finally to the granulosa cells surrounding zona pellucida of degenerating oocyte. Pyknosis of granulosa cells was the first sign of apoptosis. In immunohistochemistry, macrophages were found only in the granulosa layer at the stage of beginning of apoptosis. With progression of apoptosis, they were proliferated greatly in number enough to eliminate all the apoptotic bodies, and found within the follicular antrum. In advanced stage of atresia, macrophages surrounded the zona pellucida of degenerating oocyte, and found also in the theca interna. In transmission electron microscopy, phagocytic granulosa cells maintained characteristic gap junctions with neighboring granulosa cells and contained several apoptotic bodies and lipid droplets within their cytoplasm. Macrophages kept many apoptotic bodies, vacuoles and autophagosomes in their cytoplasm. Apoptotic granulosa cells were ingested by intact granulosa cells and macrophages initially, but lately, all the apoptotic granulosa cells and degenerated oocyte were eliminated by macrophages. Ovarian follicular atresia completed with phagocytosis of apoptotic theca interna cells by macrophages, and the remnants of the atretic follicle became ovarian stroma. It is well known that macrophages may play an important role during follicular atresia, such as elimination of apoptotic granulosa cells, theca interna cells and degenerated oocytes, but, the valid action mechanisms of macrophages on the initiation of granulosa cell apoptosis and on the completion of atresia through the secretion of paracrine factors and autocrine factors still unclear.

Morphological Study on the Radiation-induced Follicular Atresia and the Follicular Macrophage / 대한산부인과학회잡지

OBJECTIVE: It is well known that X-ray induces follicular atresia, but the exact mechanism of atresia is not still unveiled completely. In addition, the role of macrophage related with clean-up the dead granulosa cells and other functions within the ovarian follicle is emphasized recently. The aim of this study is to assess the radiation-induced morphological changes of ovarian follicles and follicular macrophages. METHODS: 8 Gy X-ray irradiated on the 3-week old rats (Sprague-Dawley strain), sacrificed at 6, 12, and 24 hours after irradiation, and performed morphological studies with light and transmission electron microscopy, TUNEL, and macrophage immunohistochemistry. RESULTS: Follicular atresia increased significantly (p<0.01) at 6 hours after X-irradiation, and it was decreased significantly (p<0.01) at 12 and 24 hours after irradiation. X-ray induced chromatin condensation in the nucleus and nuclear fragmentation of granulosa cells, which were the typical features of apoptosis. Apoptotic granulosa cells were phagocytosed by the neighboring normal granulosa cells and the macrophages. During atresia of follicles, radioresistant granulosa cells were found in some follicles, which showed similar features morphologically with the granulosa cells of normal follicles. Macrophages were found both within the antrum and at the follicular granulosa layer. CONCLUSION: X-radiation induced follicular atresia by means of granulosa cell apoptosis, and radioresistant granulosa cells which have similar features morphologically with the granulosa cells of normal follicles were observed in some follicles. And the macrophages which phagocytose the apoptotic granulosa cells were located within the follicular antrum and at the follicular granulosa layer.

Distribution of trkA in cerebral cortex and diencephalon of the mongolian gerbil after birth

TrkA is essential components of the high-affinity NGF receptor necessary to mediate biological effects of the neurotrophins NGF. Here we report on the expression of trkA in the cerebral cortex and diencephalon of mongolian gerbils during postnatal development. The expression of trkA was identified by immunohistochemical method. In parietal cortex and piriform cortex, higher levels of trkA-IR (immunoreactivity) were detected at 3 days postnatal (P3) and at P9. Although trkA was not expressed till P3 in the parietal cortex, it was detectable at birth in the piriform cortex. Several regions, such as Layers I, IV & VI, did not show much expression. Layer I showed especially weak labeling. In the hippocampus, thalamus, and hypothalamus, higher levels of trkA-IR were detected at P6 and P12 than earlier days. But trkA was not expressed at birth in the hippocampus, at P3 in the reticular thalamic nucleus (Rt), or neonatally in the dorsomedial hypothalamic nucleus (DM). This data shows that expression of trkA is developmentally regulated and suggests that high affinity neurotrophin-receptors mediate a transient response to neurotrophines in the cerebral cortex and diencephalon during mongolian gerbil brain ontogeny.

The Effect of X-irradiation on the Developing Incisor Tooth of the Rat / 체질인류학회지

In the development of tooth, the first sign is the localized thickening of oral ectoderm to form the tooth bud, and then through the dialogue between the bud and underlying mesenchyme, proliferation and differentiation of bud cells and surrounding mesenchymal cells continue, and cap and bell stages follow. In each step of development, various teratogens may act directly and indirectly, and may result a certain congenital anomalies. To reveal the action mechanism of ionizing radiation on odontogenesis morphologically, 4 Gy X-ray irradiated on the rat (Sprague-Dawley strain) fetus on GD 12.7, and observed the histological changes of the upper incisor tooth from GD 13.5 to GD 20.5, daily. In the normal development of upper incisor tooth of rat, the bud stage was from GD 12.5 ~GD 15.5, the cap stage was from GD 16.5 to GD 17.5, and the bell stage was GD 18.5 to GD 20.5. After X-irradiation on GD 12.7, the development of incisor tooth was delayed markedly, the bud stage was prolonged from GD 13.5 to GD 17.5, and the cap stage was GD 18.5 and the bell stage was from GD 19.5 to GD 20.5. After X-irradiation, from GD 13.5 to GD 16.5, apoptosis is observed in the dental organ and surrounding mesenchyme, hemorrhagic necrosis began from GD 16.5 at the center of dental pulp, followed ischemic necrosis of dental organ and surrounding mesenchyme. After GD 19.5, the development of tooth was ceased. These suggest that at least 2 mechanisms involved during X-ray teratogenesis on developing tooth. After X-irradiation on GD 12.7, initially, X-ray induced apoptosis of the cells of dental lamina and dental bud, which resulted the delayed proliferation and differentiation of dental bud and shortage of the number of cells having signal molecules which induce aggregation of the underlying mesenchymal cells. Lately, disorganization of the endothelial cells differentiated from the damaged mesenchymal cells, which resulted in rupture of capillaries and the hemorrhagic necrosis.

Morphological Study on the Arterial Intimal Hyperplasia and the Inhibitory Action of Dexamethasone / 체질인류학회지

This study is performed to reveal the changes of the arterial wall, especially, tunica intima and tunica media, after endothelial denudation and the effects of dexamethasone sodium on intimal hyperplasia morphologically in the rat. After arterial denudation by modified air drying technique, dexamethasone 1, 200 mg/kg/day was administered intramuscularly daily from the day of operation for 14 days. At 5 DAT (days after treatment) and 14 DAT, tunica intima was greatly thickened in control groups compared with normal group, but not in the dexamethasone-treated groups. Light microscopically, greatly increased cells and intercellular matrix in the tunica intima are observed in control group, but not in the dexamethasone-treated group. In the TEM observation, the cells considered as myofibroblasts and extracellular matrix were greatly increased in both tunica intima and tunica media just below the internal elastic lamina in the control group. Myofibroblasts and extracellular matrix migrated through the apertures of internal elastic lamina into the endothelial layer. Characteristic false internal elastic lamina also found. In dexamethasone-treated group, myofibroblasts and extracellular matrix decreased significantly, and apoptotic electron-dense cells, fragmented nucleus and autophagic vacuoles are observed. Through the apertures of internal elastic lamina, comma-shaped fragmented nuclei migrated into the tunica intima. These results suggest that dexamethasone inhibits the myofibroblast-transformation and proliferation of smooth muscle cells, migration of myofibroblasts and matrix synthetic activity, and induces the apoptosis of smooth muscle cells under the internal elastic lamina.

Molecular Epidemiologic Study of Urinary Tract Infection by Myroides species (Flavobacterium odoratum) / 감염과화학요법

BACKGROUND: Myroides species are widely distributed in nature, but clinical infection by these organisms are extremely rare. We report herein prolonged outbreak of urinary tract infection by Myroides species. METHODS: Forty-four Myroides spp. were isolated from urine samples from 25 patients over a period of nine months, and random amplified polymorphic DNA (RAPD) method was performed to characterize the genotype of these isolates. RESULTS: All of the subjects were hospitalized patients with indwelling urinary catheter. Five of the patients showed concomitant pyuria, which could be considered as evidence of urinary tract infection, and isolation of these organisms in the remainder of the patients could be considered as simple colonization. All the isolates were resistant to antimicrobial agents tested. RAPD analysis showed identical DNA fingerprinting patterns in all the isolates. CONCLUSION: This study revealed that all the Myroides spp. isolated from urinary specimens of prolonged outbreak were genotypically the same. Because of its resistance to multiple antimicrobial agents, prevention of dissemination of this strain is clinically important.

Molecular Epidemiologic Study of Urinary Tract Infection by Myroides species (Flavobacterium odoratum) / 감염과화학요법

BACKGROUND: Myroides species are widely distributed in nature, but clinical infection by these organisms are extremely rare. We report herein prolonged outbreak of urinary tract infection by Myroides species. METHODS: Forty-four Myroides spp. were isolated from urine samples from 25 patients over a period of nine months, and random amplified polymorphic DNA (RAPD) method was performed to characterize the genotype of these isolates. RESULTS: All of the subjects were hospitalized patients with indwelling urinary catheter. Five of the patients showed concomitant pyuria, which could be considered as evidence of urinary tract infection, and isolation of these organisms in the remainder of the patients could be considered as simple colonization. All the isolates were resistant to antimicrobial agents tested. RAPD analysis showed identical DNA fingerprinting patterns in all the isolates. CONCLUSION: This study revealed that all the Myroides spp. isolated from urinary specimens of prolonged outbreak were genotypically the same. Because of its resistance to multiple antimicrobial agents, prevention of dissemination of this strain is clinically important.

Germinal Center Formation and Integrins Expression in the Rat Thymus After 5-Fluorouracil Treatment / 대한해부학회지

Thymus is a lymphoid organ forming T-cells from hematogenous stem cells. There is no report on the germinal centers in the thymus except the Myasthenia gravis in human. In this study, new germinal centers were experimentally induced from 6 days after 5-FU treatment in the Sprague-Dawley rats. With germinal center formation, proteins of molecular weight 123 kDa on 6 days after 5-FU treatment, and 162 kDa and 205 kDa on 9 days after 5-FU treatment were increased in 5-FU treated group. These proteins revealed alpha 1 -and beta 1 -integrins on integrin Western Blot. In this experiment, it was cosidered that alpha 1-integrins and beta 1 -integrins were the key proteins for proliferation of B cells within the newly formed thymic germinal centers and the massive apoptotic disposal of B-cells from the germinal centers, and the new formation of T cells within the cortex.

The Effect of X -irradiation on Lens Development / 체질인류학회지

For the study the effects of X -ray irradiation on the development of lens and interactions between optic vesicle and lens, 200 rads X -ray irradiated to the preganat rats (Sprague -Dawley strain) on gestation day 9.5. The rats were sacrificed daily from the gestation day 10.5 to 17.5, and investigated the development of lens with light microscope. The results were as follows; 1. The survival rate of X -irradiated rat fetuses was decreased significantly compared with that of the control group. 2. The mean body weight of the X -irradiated rat fetuses was decreased significantly compared with that of the control group. 3. The congenital anomalies of the eye in the rat fetuses after X -irradiation were anophthalmia, congenital aphakia, lens aplasia, lens luxation, and coloboma of the retina. 4. The critical period of lens development of the Sprague -Dawley rats was considered from GD 9. 5 to GD 10.0. 5. In the X -irradiated rat fetuses on gestation day 9.5, optic vesicle did not developed, but lens developed independently , and moved deeply toward the forebrain vesicle. According to above results, it could be concluded that the development of lens from surface ectoderm might be independent from the inductive influence of optic vesicle, and the movement of lens toward the forebrain vesicle could be mediated by chemotactic factors secreted from the brain vesicle. Further studies are needed to reveal the mechanisms of lens development and interaction between lens and brain vesicle.