Serous otitis media is closely related with auditory tube function, but its etiology and pathogenesis are not clearly defined yet. So we tried to prove the theory of hydrops ex vacuo via the experimental study with cats by means of obstructing the pharyngeal orfice of the auditory tube and observe the serial changes in tympanic mucosa through light and electron microscopy. The results are as follows; 1. We confirmed the production of serous otitis media with auditory tube obstruction and have a new understanding of auditory tube function in middle ear aeration. 2. The effusion in serous otitis media was produced from the next day of experiment and increased till the fourteenth day, but decreased after the spontaneous perforation of ear drum. 3. Through the light microscopy, we observed the increasement of the sercretory cells including goblet cells, epithelial hyperplasia, capillary proliferation and invasion of inflammatory cells. 4. Through the elctron microscopy, we observed the protrusion of secretory cells, blobs in cilia, loss of cilia, increasement of vesicles, vacuoles and dense bodies in ciliated cells and Invasion of inflammatory cells. With above results, we concluded that aeration through auditory tube is the most important factor in serous otitis media and presumed the effusion was secreted by secretory cells.

A number of recent ultrastructural studies have shown marked differences between the two lining cell types in adult liver sinusoids, endothelial cells and Kupffer cells. In the present study, the ultrastructural features and electron microscopic cytochemistry of sinusoidal lining cells in the fetal liver were studied through fetal period to neonate in the rat. At fetal period, the sinusoid, which contains various blood component, in lined by the endothelial cells, the Kupffer cells and the fat storing cells that located in the space of Disse. As gestation proceeded, these eel's are arranged as adult liver sinusoids. The sinusoidal wall appears to be discontinuous with open fenestration between endothelial cells, but no basal lamina can observed. It seems to be morphologically and functionally distinct at the early gestation between the endothelial cells and the Kupffer cells, the latter showing marked phagocytized activity. The fat storing cells, which contain several fat droplets, are located in the space of Disse. Ultrastructural localization of the acid and alkaline phosphatase activity were noted on the sinusoidal lining cells.

Caulubacter is distinctive in the morphology and replication and ubiquitous in the biosphere, especially in every type of aquatic environment. In water and waste-water treatment processes, chlorine and chlorine compounds have been used as a main disinfectant throughout the world. Therefore, Caulobacter in the waters should be affected by chlorination of the waters. The objective of this study is to determine the effects of the disinfectants on Caulobacter cells and on the developmental processes of the cells. The Caulobacter swarmer cells were disinfected by chlorine at pH 7.0 minutes of the reaction with 2.0 mg/l of infected at pH 10.0. The swarmer cells treated with 2.0 or 4.0 mg/l of chlorine for 15 minutes lost their flagella and were observed by electron microscopy to be damaged on their cell surfaces, discharging some cellular materials. When the chlorinated swarmers and untreated control samples were recultivated in fresh PYE broth medium, the control swarmers multiplicated exponentially after one-hour lag phase, whereas the chlorinated swarmers extended the lag phase to about four hours. During the extended lag phase, the cells were proved by electron microscopy to be grown and be in predivisional step, but no swarmer cell was found. When the stalked cells were chlorinated, almost all the cells were observed to have their stalks broken and some cellular materials discharged. In those samples recultivated, many cells differentiated to possess an abnormally elongated stalk with several crossbands on it. This suggests that the chlorine-shocked Caulobacter cells can develope to abnormal morphology in water environments which they can survive and regrow in.

Several phages of Bacillus thuringiensis distributed in Korea were isolated. The distribution and morphological characteristics of phages were studied. The results are as follows; 1. The isolated phages were highly specific for Bacillus thuringiensis var. thuringiensis. They were classified as YM series phages and designated as phage YM-1, YM-2 and YM-3 according to their morphological characteristics. 2. Most of these YM series phages were isolated from compost including domestic animal dung and soil under sewage. 3. The YM-1 phage was similar to Bacillus subtilis ${\phi}25$ in morphology. It has 94nm x 86nm head, contractile tail sheath and base plate with four cornered structure. 4. The YM-2 phage was similar to Bacillus subtilis GA-1 phage in morphology. It had 70nm x 56nm head and tail without contractile tail sheath. 5. The YM-3 phage was similar to Bacillus subtilis ${\phi}29$ phage. It had 56nm x 43nm head and tail with distal enlargement.

Mycosis fungoides is an uncommon, chronic fatal disease of lymphoreticular system associated with primary ski3 involvement for many years and terminating as a malignant lymphoma with involvement of lymph nodes and viscerae. On occasion it simulates numerous other nonspecific benign skin lesions, thus it may be impossible to decide whether the infiltrate represents early mycosis fungoides or nonspecific on the histopathologic ground alone. A case of mycosis fungoides was confirmed by electron microscopy and reported here. The patient was 69-years-old male who had suffered from erythematous scaly eruption on the whole body since 10 years. Skin biopsies of 4 times showed focal ulceration with chronic nonspecific inflammation and polymorphic cell infiltration in lower dermis, thus possibility of mycosis fungoides could not be completely ruled out. Electron microscopically several atypical lymphoid cells, which had a large cerebriform nucleus with peripheral condensation of dense chromatin and scant cytoplasm, were noted in the upper dermis. Intraepidermal infiltration of these atypical cells was also seen. It was thought that the electron microscopic study may be very helpful to differentiate equivocal mycosis fungoides from the nonspecific dermatosis.

전신성 Cryptococcosis로 판명된 4세 남아의 피부 생검조직에서 발견된C. neoformans의 미세구조를 광학현미경 관찰과 함께 보고 하였다. 광학현미경 관찰에서는 각종 만성 염증 세포의 침윤과 함께 다수의 구형의 organism을 관찰할 수 있었다. 전자현미경적으로도 난원형의 세포가 gelatinous 또는 filamentous한 capsular material에 둘러 싸여 단세포 혹은 여러개의 세포가 모여 있는 상태로 관찰되었으며 budding중인 상태의 것도 관찰되었다. 세포막은 고전사 밀도의 여러층으로 구성되어 있었으며 한개의 핵과 핵인이 관찰되었고 세포질내에는 mitochondria, ribosome, lipid bodies, vacuole등과 함께 plasma membrane의 infolding으로 형성된 mesosome-like structure도 관찰되었다.

Cyclical changes in the fine structures of endometrial stroma of guinea pig during the estrous cycle were studied by electron microscopy. Cytochemical studies were made in order to investigate the ultrastructural localization of the acid phosphatase,alkaline phosphatase and ATPase in these cells. The results obtained are as follows: 1. During estrus collagen fibers were most abundant in the stroma. The stromal cells showed increases in the number of several cytoplasmic organelles, especially the rough endoplasmic reticulum was significantly increased and the structures were greatly differentiated. 2. Many cytoplasmic processes and cell debris have been distributed in the stroma of metestrus. The distributions were increased and degenerated mitochondria were observed during diestrus. 3. Cytochemical studies indicated that during metestrus and diestrus acid phosphatase activities were localized in the degenerating collagen fibers. Alkaline phosphatase activities were weak in the collegen fibers during proestrus and estrus which intense activities were localized around the cell membrane during metestrus and diestrus. ATPase activities were present on the cell membrane and intercellular space of stromal cell during proestrus and estrus.

The phages of Bacillus subtilis SNU 816 were observed by electron microscope with their host. The results are as follows; The phage had hexagonal head, contractile tail sheath and base plate with six tail fibers. During the lysis of bacteria due to attack of phage, dissolution of flagella were initiated from distal end of flagella.