Electron microscope study of lens fibers

The in vitro swelling action of L-thyroxine on rat liver mitochondria as examined photometrically represents an acceleration of a process which the mitochondria are already inherently capable of undergoing spontaneously, as indicated by the identical kinetic characteristics and the extent of thyroxine-induced and spontaneous swelling, the nearly identical pH dependence, and the fact that sucrose has a specific inhibitory action on both types of swelling. However, thyroxine does not appear to be a "catalyst" or coenzyme since it does not decrease the temperature coefficient of spontaneous swelling. The temperature coefficient is very high, approximately 6.0 near 20 degrees . Aging of mitochondria at 0 degrees causes loss of thyroxine sensitivity which correlates closely with the loss of bound DPN from the mitochondria, but not with loss of activity of the respiratory chain or with the efficiency of oxidative phosphorylation. Tests with various respiratory chain inhibitors showed that the oxidation state of bound DPN may be a major determinant of thyroxine sensitivity; the oxidation state of the other respiratory carriers does not appear to influence sensitivity to thyroxine. These facts and other considerations suggest that a bound form of mitochondrial DPN is the "target" of the action of thyroxine. The thyroxine-induced swelling is not reversed by increasing the osmolar concentration of external sucrose, but can be "passively" or osmotically reversed by adding the high-particle weight solute polyvinylpyrrolidone. The mitochondrial membrane becomes more permeable to sucrose during the swelling reaction. On the other hand, thyroxine-induced swelling can be "actively" reversed by ATP in a medium of 0.15 M KCl or NaCl but not in a 0.30 M sucrose medium. The action of ATP is specific; ADP, Mn(++), and ethylenediaminetetraacetate are not active. It is concluded that sucrose is an inhibitor of the enzymatic relationship between oxidative phosphorylation and the contractility and permeability properties of the mitochondrial membrane. Occurrence of different types of mitochondrial swelling, the intracellular factors affecting the swelling and shrinking of mitochondria, as well as the physiological significance of thyroxine-induced swelling are discussed.     

An electron microscope study of the regenerating nerve fibers

Summary Guinea pig sciatic nerves were severed in order to obtain a regenerative process of the nerve fibers. The animals were killed at different periods of time after the severing (24 hours, 6 days and 12 days) and the specimens obtained were prepared for electronmicroscopic study.The nerve fiber growing extremities (growing cones) were specially studied. The growing cones showed the following components: a) microvesicles; b) mitochondria; c) multivesicular bodies.The microvesicles are hollow elements of about 200 to 700 Å. They constitute the main component of the growing cone. The mitochondria were seen as elongated bodies of 80 m. They were seen in many cases changing to round dense bodies which appear to break-up in irregularly-shaped fragments.The multivesicular bodies were found present in most of the growing cones. Protoneurofibrils do not exist in the growing cone but a close relationship between microvesicles and protoneurofibrils was found in the segments next to the growing cone.The above-mentioned components were found in all growing cones, disregarding the time elapsed after the nerve severing.Director of the Institute.Assistant of the Department of Neurohistology and Experimental Histology.Head of the Department of Cell Ultrastructure.     

不同品种烟草花粉电子显微镜观察

通过对10个烤烟品种、8个晒烟品种、2个野生种的花粉进行扫描电子显微镜观察,发现同为烤烟或晒烟的烟草,其花粉的形态、大小、外壁纹饰比较稳定。野生烟在供试种中具有独特的细网状外壁纹饰,是鉴别野生烟与非野生烟的一条有效途径。     

Morphological study of the bovine blastocyst with phase contrast microscopy

The morpholoqical appearance of 40 bovine blastocysts. collected from single ovulating heifers 7 days after oestrus was evaluated with the aid of a phase contrast inverted microscope. Out of 40 blastocysts, 17 were classified normal (N), 14 in the process of degeneration (IPD) and 9 degenerated (D). There was no difference in the mean diameters of the three groups of blastocysts, whereas the mean diameters of cell mass was bigger in N than IPD and D blastocysts. This difference was highly significant (P < .005). The mean number of cells was greater in normal than in abnormal (99 vs 58). This difference was highly significant (P < .005). The results reported here indicate that the criteria used for classification of the morphological appearance of the 7 day old bovine blastocyst reflected the degree of cellular organization and the number of cells.     

The effects of various hormones on the surface morphology of testicular cells in culture.

The purpose of this investigation was to study the effects of various hormones on the surface morphology of 20-day-old rat testicular cells in culture. Aggregates containing primarily Sertoli cells and germinal cells were obtained by enzymatic digestion. The surface morphology of the cells composing these aggregates was characterized under various culture conditions using light microscopy and scanning electron microscopy. The cytoplasmic processes of Sertoli cells became highly branched and filamentous after being cultured in the presence of rat, human or ovine FSH. Identical branching and filamentation was observed when Sertoli cells were cultured in rat TSH. Finally, numerous large blebs were observed on the surfaces of germinal cells cultured in the presence of insulin. These results suggest that the branching and filamentation of Sertoli cell cytoplasm observed after FSH stimulation are not specific for that hormone.     

Peculiarities of the growth and morphology of human fibroblasts cultured on substrates modified with nanosized fibers of collagen and chitosan

The relationship between cell morphology and the topography and composition of a substratecoating material based on nanosized fibers of collagen and chitosan was studied during culturing the cell culture of normal human embryonic fibroblasts. The morphology of cells grown on modified substrates (in particular, the number of cilia and flagella up to 100 nm in diameter) was studied by atomic force microscopy at the submicron level in comparison with their proliferative activity on glass substrates. Methods for controlling the growth activity by changing the structure and composition of the coating material were proposed. The effect of the reduced pH of the coating material surface on growth activity and cell morphology was studied. Methods of spray application of colloidal solutions of biopolymers were proposed.