The ultrastructure of freeze-substituted Malpighian tubule cells of German cockroach after rapid freezing was compared to that fixed with conventional chemical fixation. As results, freeze-substitution proved to be the superior technique revealing much more structural details of the tissue cells. Especially, all kinds of membrane structures including infoldings, microfilament, microtubules and ribosomes were best preserved in this material.

The morphological characteristics and changes of the foregut in the grasshopper (Oxya sinuosa Mistshenko) have been studied with the special reference to the developmental stage. In light microscope level, the epithelia are seen the cuboidal shape in the 5th instar nymph and the adult. A number of pigment granules are appeared in the cuboidal epithelium of the 5th instar nymph, however the pigment granules were a few in the adult. Indistinct or undifferentiated folds of the epithelial layer were appeared in the 5th instar nymph, whereas the well-developed folds were in the adult. The well-developed muscular layers are seen in the 5th instar nymph, however in the adult the muscular layers are appeared thin or a few layer except the crop. In electron microscope level, in the foregut epithelium, a few round or oval shaped mitochondria, well-developed rER, Golgi complex, lysosome and a number of vacuoles were appeared in the cytoplasm. Two types of pigment granules, electron dense or homogenous and low electron dense or lamellar profiles, are seen in the esophageal epithelium. The crystalline profiles and plasma membrane infoldings were also appeared. In the foregut epithelium of the 5th instar nymph, however the cell organelles were generally undifferentiated and in the crop two types of pigment granules as the adult esophageal epithelium were also found.

Several types of the epithelial cells were classified by ultrastructural observation through transmission electron microscope in the rat epididymis. Ultrastructural studies showed that the principal cells, basal cells and narrow cells are located in all the regions of the epididymis and the light cells are present only in the corpus and cauda epididymis. It was observed that the columnar epithelial cells like the principal cells, light cells and narrow cells contain several secretory vesicles and there are halo cells migrating in the several regions. The basal cells showed the elliptical forms in the caput and corpus region and the global forms in the cauda region.

Ultrastructural and spectrophotometric studies on mitochondrial swelling and contraction were carried out. All mitochondria just after isolated from rat liver showed condensed conformation. When mitochondria were incubated in 0.25 M sucrose only, they were moderately swollen and the absorbance at 520 nm was slightly decreased. Adding ATP to sucrose caused the absorbance to increase and the mitochondria to contract partially. KCl solution of 0.3 M induced marked decrease of absorbance and swelling of mitochondria. When ATP was added to KCl, increase of the absorbance and no contraction of the mitochondria excluding increased electron density of mitochondrial intermembranes were observed. Markedly decreased absorbance and somewhat largely swelled mitochondria in sodium arsenite solution of 0.4 or 1.0 mM were observed. When ATP was added to sodium arsenite, the absorbance increased slightly but mitochondria were more contracted than those in KCl-treated group. Above results indicate that the absorbance may not be correlated to morphological observations in the mitochondrial swelling and contraction.

Ultrastructure of the hemopoietic organ in the grasshopper, Euprepocnemis shirakii, was studied using light and electron microscopes. The hemopoietic organs located on the upper surface of the dorsal diaphragm between 1st and 8th segments were consisted of 3 kinds of cells; the reticular cells, stem cells and two types of granulocytes. The reticular cells had numerous cytoplasmic processes and forming a complex network. Characteristically, pinocytotic vesicles and rough endoplasmic reticulum were well developed in this cell. The stem cells give rise to differentiating hemocytes of the different cell lineages. Granulocytes within the hemopoietic organs were originated from the stern cells and differentiated into two types of hemocytes ; granulocyte( I ), granulocyte( II ).

Characterization and electron microscopic visualization of the plasmid and the gene expression of Escherichia coli were carried out. Transcriptional units of active structural genes were observed after lysis of Escherichia coli cells. The ribosomes attached to the E. coli genome on mRNA molecule as polyribosomes. From this gradient of polyribosome length, we estimated location of mRNA synthesis initiation site. In this experiment, a granule is ofen present which may correspond to a RNA polymerase at the promoter site. pOX1, pOX7, pOX7A, $pOX7{\Delta}1$, pSTP36, pSTP21, pBR322, and pJH12 were visualized by way of electron microscope, and their estimated sizes were determined to be $5.70{\pm}0.08{\mu}m,\;2.15{\pm}0.10{\mu}m,\;2.14{\pm}0.12{\mu}m,\;7.39{\pm}0.08{\mu}m,\;4.03{\pm}0.04{\mu}m,\;1.50{\pm}0.03{\mu}m\;and\;1.25{\pm}0.09{\mu}m$ respectively. One micrometer of measured length corresponded to about 3.0 Kb. Mica-press adsorption method that allows selectivs visualization of the plasmid DNA released in situ from the bacterial cell is rapid and useful for visualization of plasmids. The released plasmid DNA was adsorbed preferently on mica in a divalent cation-free solution. Miller chromatin-spreading method was useful to observe the plasmid and transcripts. BAC method and cytochrome C monolayer were useful to observe the plasmid DNA. Our ability to visualize ultrastructural aspects of the expression of E. coli has given us a unique tool with which to study the regulation the level of an individual gene.

It was investigated the morphological changes of differentiating epidermal cells in chick embryos. Ectodermal cells at 3 days after incubation were cuboidal, their nuclei were large, and rough endoplasmic reticulum and mitochondria were distributed in the cytoplasm. At 5 days after incubation, there were periderm and one basal layer in epidermis. The cells of basal layer were columnar, their nuclei were round, and rough endoplasmic reticulum and free ribosomes were developed. Also, peridermal cells were flat, chromatins were partially condensed and glycogen particles were abundant. No periderm showed and cells of basal layer formed intermediate layer at 9 days after incubation. Basal cells of intermediate layer were cuboidal, neighboring cells were anchored by desmosomes and tonofibrils and free ribosomes were evenly scattered. At 15 days after incubation, stratum corneum and stratum germinativum were distinguished. In cells of stratum germinativum, tonofibrils, free ribosomes and desmosomes were well developed. And then, the shedding of stratum corneum were showed at 17 days after incubation and stratum corneum were well developed after hatching.

Toad bladder의 상피수송(上皮輸送)을 분석(分析)하기 위하여 동결치환(凍結置換) 및 동결절단법(凍結切斷法)을 적용(適用)하여 전자현미경(電子顯微鏡) 관찰(觀察)을 실시하였다. 방광(膀胱)의 점막층(粘膜層)은 과립성세포(顆粒性細胞), 미토콘드리아가 풍부한 세포, 점막분필세포(粘膜分泌細胞) 및 기저세포(基底細胞)등 4가지 세포로 구성되어 있었다. 과립성세포(顆粒性細胞)는 점막표면적의 대부분을 점유하며 $Na^+$ 수송(輸送)에 주요한 역할을 하고, 정단부(頂端部)의 세포질에는 다수의 과립이 분포하며 정단세포막(頂端細胞膜)은 microvilli type I로 배열되어 있고, 표면에 glycoprotein을 함유하는 세포외막(細胞外膜)이 관찰되었다. 대조적으로 미토콘드리아가 풍부한 세포는 세포질 전역에 걸쳐 다수의 미토콘드리아가 분포해 있으며 주요 기능은 $H^{+},\;K^{+}$ 및 $HCO_{3}^{-}$ 분필수송(分泌輸送)에 관여할 것으로 생각되며 이들 수송상피(輸送上皮)는 정단부가 견고연접(堅固連接)으로 둘러 싸이고 기저세포막(基底細胞膜)은 인접세포와 서로 분리되므로 상피세포의 극성이 유지되며 정단부(頂端部) 세포막과 기저세포막의 수송특성(輸送特性)은 각기 다르다고 생각된다. 따라서 두꺼비 방광(膀胱)에서 상피수송(上皮輸送)은 세포 통과수송 및 세포간 분류수송 경로를 나타내고 있다. 한편 세포막 투과성(透過性)의 조절과 관련하여 동결절단(凍結切斷) 전자현미경 관찰에 의하면 forskolin에 촉진된 정단부(頂端部) 세포막 투과성의 변화는 세포막내(細胞膜內) 입자(粒子)의 분포와 밀접한 관계를 가지는 것으로 보인다. 특히 과립성세포(顆粒性細胞)에서 집단으로 관찰되는 세포막내(細胞膜內) 입자(粒子)는 forskolin에 유도된 정단세포막(頂端細胞膜) 투과성의 변화를 나타내주는 것으로 사료되나 이의 기능적 의미에 대하여는 연구가 더욱 필요하다고 본다.

To investigate the ultrastructural features of rat back skin tumor induced by 7, 12-Dimethylbenz[a]anthracene(DMBA), morphological changes during carcinogenesis were undertaken by the light and the electron microscopes. On the light microscopic levels, dysplasia was observed at the 6th week of treatment with 0.5% DMBA, hyperplasia at the 8th week, and carcinoma in sitv or invasive carcinoma at the 12th week. In addition to those characteristics, papillomatosis was observed at the 18th week. Under the electron microscopy, intercellular spaces were enlarged in the early phase. Nucleolar enlargement, the increase of free ribosomes, the condensation of tonofibrils, and the irregular arrangement of desmosomes appeared at the 6th week of application. Thereafter, the degradation of desmosomes and the discontinuity of basal lamina were characterized. And then, epidermal cell processes were protruded toward the connective tissue at the site of discontinuity of basal lamina at the 12th week. At the 14th to 18th week, DMBA-induced fibrosarcomas or papillomas were observed.

Structural changes of the vitelline envelopes during oogenesis of a polychaete, Nectoneanthes oxypoda, were examined with a scanning electron micrscope. Oocytes grow in the same coelomic fluid to the final stage, but the surface appears to change in the structure during oogenesis. Projections, which were identified to be microvilli, change in shape, number and size. Short microvilli, which cover the surface of oocyte of $33{\mu}m$ diameter densely, grow in length, reaching a maximum at the stage of $73{\mu}m$. The number of microvilli increases with the stages of oogenesis, reaching a plateau at the stage of $82{\mu}m$. The observations suggest that control of material transport including yolk precursor proteins may be correlated with the structural changes in the microvilli.

This study was investigated to elucidate the effect of chlorambucil on the heart in aging rats. Male rat ranging in age from 3 to 36 months were used. Each age groups(3, 6, 12, 18, 24, 36 months) included control and chlorambucil treated rats. As a part of the study, the ultrastructural changes in the left ventricular myocardial cells were described by using the qualitative and morphometric techniques. The results are summarized as follows. Age associated ultrastructural changes included: an increase in vacuoles, protrusion of plasma membranes, lipid droplets, and lipofuscins in myocardium of control groups. These changes which begin to occur at 12 months and continue through 36 months. At the 36 months some instance of unusual formation of contraction band and separation of intercalated discs were encountered. Morever, these changes and contents with chlorambucil treatment were remarkably increased in comparison with control groups. Age-dependent changes of control group measured with morphometry were not observed in the volume densities of mitochondria and myofibrils. But there was increase in interstitium. On the other hand decrease in sarcoplasmic reticulum and T-tubule system. In chlorambucil treated groups, volume densities of mitochondria and interstitium were increased in comparison with those of the control groups. But sarcoplasmic reticulum and T-tubule system were remarkably decreased.