The present study was performed to clarify the effect of vagus nerve stimulation on the enterochromaffin(EC) cells in the body of the stomach, the first part of the duodenum and the ceceum of rats by using routine electron microscopy and immunogold labelling. The changes in the ultrastructure and in the labelling density of the gold particles of the EC cells were investigated after vagus nerve stimulation. The vagus nerve was electrically stimulated with a square wave pulse generator for a duration of 5 minutes each, a total of 8 times at 2 minute intervals. Immunogold labelling demonstrated that the epithelial serotonin immunoreactive cells of the gastrointestinal tract are EC cells containing characteristic pleomorphic granules. Immunocytochemically labelled gold particles were largely concentrated in the dense matrix of the granules of the EC cell, and the labelling density of the gold particles considerably increased after the vagus nerve stimulation. Except for a slight activation of Golgi complexes, no remarkable changes in the ultrastructures of the EC cells were noted after the vagus nerve stimulation. The above results suggest that vagus nerve stimulation may activate serotonin biosynthesis in EC cells.

Ultrastructural aspects on the production of the duct cuticle and formation of cuticular precursors within silk glands of the orb web spider, Nephila clavata L. Koch(Araneae: Araneidae), were studied using transmission electron microscope. Four kinds of silk glands(ampullate glands, tubuliform glands, flageliform glands, and aggregate glands), which connected with large spinning tubes(spigots) of the spinnerets, were examined and discussed in terms of cuticle precursor production. Inner cuticular intima which composed of three layers of cuticles-subcuticle, endocuticle and exocuticle- were commonly originated from duct epithelial cells surrounding the cuticle. The morphology and internal textures of each cuticle precursors were very diverse according to the types of silk glands. However several common features were observed. These cuticle precursors were first produced from the rough endoplasmic reticulum and next concentration was accomplished through the Golgi complex. After this step, cuticle precursors were released to the cuticle layer as a form of secretory granule by the mechanism of merocrine secretion commonly.

To compare the quality of ultrastructural preservation of Scanning Electron Microscopic specimens dried with different methods; pure air-drying, air-drying with using Tetramethylsilane(TMS), four kind of air-drying using Hexamethyldisilazane(HMDS) and critical point drying(CPD), we conducted scanning electron microscopic observation on liver, skeletal muscle and intestinal tissues from laboratory rat treated with each method. In pure air drying group, severe distortion of tissue surface was observed, and in HMDS treated group, only liver tissue showed slight distortion. But in TMS treated group, each tissue showed a good presentation comparable to CPD group. The results suggest that the method of air-drying using TMS may be the former is less expensive and simple be and also time-saving.

The results of observation on the salivary gland and salivary secretory duct of Korean slug, Incilaria fruhstorferi, in histochemical method are as follows. It is observed that there are six kinds of gland cells(Type-A, B, C, E and F) making up the salivary gland of Korean slug. Of those, type-A gland cell is observed as an acid mucous cell, and type-B, C, D, F gland cells as neutral mucous cells. But in type-E gland cell, while the membrane surrounding granules exhibit alcianophilia, granules show no reaction. The salivary secretory duct composing the salivary gland of Korean slug is composed of supporting epithelial cell and four kinds of gland cells(type-A, E, F and G), of which type-A, E, F gland cells compose both the acinus of salivary gland and endothelial tissue of salivary secretory duct, and are secreted into lumen through salivary secretory duct. But, type-G gland cell is observed only in the endothelium of salivary secretory duct and mucous granules are observed as neutral mucopolysaccharide.

It has been well known that ischemia and reperfusion injury to skeletal muscle following an acute arterial occlusion causes significant morbidity and mortality. The skeletal muscle, which contains high energy phosphate compounds, has ischemic tolerance. During the ischemia, the ATP is catalyzed to hypoxanthine anaerobically and hypoxanthine dehydrogenase is converted to xanthine oxidase. During reperfusion, the hypoxanthine is catalyzed to xanthine by xanthine oxidase under $O_2$, presence and that results in production of cytotoxic oxygen free radicals. These cytotoxic free radicals, $O_2^-,\;H_{2}O_2,\;OH^-$, are toxic and make lesions in skeletal muscle during reperfusion. The authors perform the present study to investigate the effects of allopurinol, the inhibitor of xanthine oxidase, on reperfused ischemic skeletal muscles by observing the ultrastructural changes of the muscle fibers. A total of 48 healthy Sprague-Dawley rats weighing from 200 g to 250 g were used as experimental animals. Under urethane(3.0mg/kg., IP) anesthesia, lower abdominal incision was done and the left common iliac artery were ligated by using vascular clamp for 1, 2 and 6 hours. The left rectus femoris muscles were obtained at 6 hours after the removal of vascular clamp. In the allopurinol pretreated group, 50mg/kg of allopurinol was administered once a day for 2 days and before 2 hours of ischemia. The specimens were sliced into $1mm^3$ and prepared by routine methods for electron microscopic observations. All preparations were stained with uranyl acetate and lead citrate, and then observed with Hitachi -600 transmission electron microscope. The results were as follows: 1. In 1 hour ischemia/6 hours reperfused rectus femoris muscles of rats, decreased glycogen particles and electron density of mitochondrial matrix and dilated terminal cisternae are seen. In 2 hours ischemia/6 hours repersed rectus femoris muscles of rats, mitochondria with electron lucent matrix, irregularly dilated triad and spheromembranous bodies are observed. In 6 hours ischemia/6 hours reperfused rectus femoris muscles of rats, irregularly arranged myofibrils, and many spheromembranous bodies, fat droplets and lysosome are seen. 2. In 1 hour ischemia/6 hours reperfused rectus femoris muscles of rats pretreated with allopurinol, decreased glycogen particle and dilated cisternae of sarcoplasmic reticulum and triad are observed. In 2 hours ischemia/6 hours reperfused rectus femoris muscles of rats pretreated with allopurinol decreased electron density of mitochondrial matrix and spheromembranous bodies are seen. In 6 hours ischemia/6 hours reperfused rectus femoris muscles of rats pretreated with allopurinol, mitochondria with electron lucent matrix, spheromembranous bodies and dilated cisternae of sarcoplasmic reticulum and terminal cistern are observed. The results suggest that the allopurinol attenuates the damages of the skeletal muscles of rats during ischemia and reperfusion.

The development of pale chub oocyte from the immature oogonium to mature oocyte was investigated by light and electron microscope. The cytoplasm of pale chub oogonia was acidic and many vesicles were located at inner side of nuclear membrane. In primary oocytes, yolk vesicles were distributed in cytoplasm. Also, fibrous materials and protuberances were distributed on the surface of zona radiata. The nucleus of secondary oocyte was enlarged and yolk vesicles in cytoplasm migrated to zona radiata. In early egg, yolk mass are formed and yolk vesicles were located at inner side of zona radiata. Three-layered zona radiata was about $3{\mu}m$ in thickness. The three layers were an outer fibrous material layer, a middle nurse cell layer in which microvilli of early egg cytoplasm contact with processes of nurse cells, and an inner layer with high electron density. In mature egg, euchromatin and a germinal vesicle were developed, mitochondria, free ribosomes, and yolk mass were distributed in cytoplasm. But, yolk vesicles were disappeared. Specially, zona radiata of matured eggs were better thin than the one of immature eggs In conclusion, it is summerized that the oogenesis of pale chub were the increase of cell size, the formation and accumulation of yolk, the decrease in nucleat electron density, changes of zona radiata, and the development of microvilli.

이상과 같은 실험에서 다음과 같은 사실을 요약할 수 있다. 1) ZnSSe/GaAs 에피층에는 많은 양의 적층결함과 전위 등의 결정결함이 존재하고 이들은 표면부 보다는 계면부에 더 많이 존재한다. 그러나 에피층은 기판과 pseudomorphic 성장을 이루고 있다. 2) ZnSSe/GaAs 계면에는 5nm 크기의 높이차가 나는 굴곡이 존재하며 ZnSe 버퍼 층에 관계없이 적층결함이 존재하고, 에피층 결정이 약간 기울어져서 므와레 줄무늬 패턴도 존재한다. 3) ZnSSe/GaAs 계면에는 성장 중에 S의 침투로 인한 <111>방향으로 피트가 형성되었음이 관찰되었고 이는 결함 생성 소스로 작용한다 4) 15nm 높이차가 나는 계면이 발견되었으나 기판과 정합을 이루고 있고 주변에는 적층결함도 존재하지 않는다. 그러나 미세한 므와레 줄무의형태가 존재하였다.

지금까지의 실험결과에서 다음과 같은 요약할 수 있다. 1) 사원계 $Zn_{1-x}Mg_{x}S_y$ $S_{1-y}$(x=0.13, y=0.16) 에피층은 다소 불규칙한 성장을 나타내어 역삼각형의 결함과 길고 직선인 적층결함으로 형성된 수지상 형태가 발견되었다. 2)역삼각형 결함은 {111}면에 형성된 적층결함으로 둘러싸여 있고 내부에는 결함이 없으나 계면과 수직인 방향인 <001>방향으로 콘트라스트 차이를 이루는 밴드가 형성되었다. 3) 기판과 정합을 이루고 있고 결함이 없는 ZnSe 버퍼 층이 관찰되었으며 결함 및 므와레 줄무늬는 버퍼층과 4원계 에피층과의 계면에서 형성된다. 4) 4원계 에피층에 형성된 적층결함은 Mg 원소의 효과로 길이가 60nm 이상 폭이 40nm 이상의 넓은 간격을 이루고 있다. 5) 긴 적층결함으로 둘러쌓인 수지상 구조에는 국부적으로 주기를 이루며 강한 콘트라스트 차이를 나타내는 줄무늬가 관찰되는데, 이는 Mg 및 S의 국부적인 화학적 조성차이에 기인한 탄성 변형 효과로 생각된다.

In the Fe-Si system, a mixture of a($Fe_{2}Si_5$) - and ${\epsilon}$(FeSi)-composition powders was sintered and heat-treated subsequently at various temperatures and time to get thermoelectric ${\beta}$-phase($FeSi_2$) compacts. The different transformational sequences depending on the heat treating temperature were found through the investigation into phase transformation and microstructural development. That is, a rapid eutectoid decomposition of ${\alpha}{\to}{\beta}+Si$ occurred together with a accompanying slow reaction between the dispersed Si formed by above decomposition and the preexisted ${\epsilon}$ phase at temperatures below $830^{\circ}C$. The unreacted Si and the micropores formed due to the density change upon the transformation coarsened as heat treating time elapsed. At temperatures above $880^{\circ}C$, however, transformation was proceeded by a peritectoid reaction of ${\alpha}+{\epsilon}{\to}{\beta}$. It took at least 200min. to achieve 90% volume fracion of transformed ${\beta}$ phase, and the growth of micro-pores was also observed in this transformational sequence with prolonged heat treating time.

The morphological changes of primary solid particles as a function of process time on hypereutectic Al-15.5wt%Si alloy during semi-solid state processing with a shear rate of $200s^{-1}$ are studied. In this alloy, it was observed that primary Si crystals are fragmented at the early stage of stirring and morphologies of primary Si crystals change from faceted to spherical during isothermal shearing for 60 minutes. To understand the role of Al dissolved in the primary Si crystal by shear stress at high temperature, lattice parameters of the primary Si crystals are determined as a variation of high order Laue zone(HOLZ) line positions measured from convergent beam electron diffraction(CBED) pattern. The lattice parameter of the primary Si crystal in the rheocast Al-15.5wt%Si alloy shows tensile strain of about 5 times greater than that of the gravity casting. Increase of the lattice parameter by rheocasting is due to the increased amount of Al dissolved in the primary Si crystal accelerated by shear stress at high temperature. The amounts of solute Al in the primary Si crystal are measured quantitatively by EPMA method to confirm the CBED analysis.