• Title/Summary/Keyword: High pressure freezing-freeze substitution

Search Result 4, Processing Time 0.022 seconds

Improved Ultrastructural Preservation of Retinal Cells in Drosophila melanogaster (초고압동결장치를 이용한 초파리 레티나 세포의 향상된 미세구조)

  • Mun, Ji-Young;Park, Se-Jin;Han, Sung-Sik
    • Applied Microscopy
    • /
    • v.37 no.3
    • /
    • pp.175-183
    • /
    • 2007
  • The Drosophila retinal cell is widely used to study cell development and cell signaling processes. In the past decades, conventional chemical fixation had been used to study the structure of retinal cells in Droscphila. Rapid freezing methods are superior to chemical fixation methods due to their fixation speed. Some Drosophila tissues, such as the eyes, should not be freezed due to their surrounding cuticle layer. Therefore, in the case of the Drosophila retina, the benefits of high pressure freezing and freeze substitution (HPF-FS) had not been verified. In this study, a retinal cell from Drosophila melanogaster had been studied by using the HPF-FS method. Compared to chemical fixation, the preservation of the cytoplasm in the HPF-FS sample was improved on the whole. The HPF-FS cell membranes were smoother than that of chemical fixation. In addition, HPF-FS preserved the mitochondria structures very well. These results of the present study suggest that HPF-FS is superior to other fixation methods for the preservation of the retinal cell structure.

Rhabdomere Formation in Late Pupal Stage of Drosophila melanogaster; Observation Using High-Pressure Freezing and Freeze-Substitution, and High-Voltage Electron Microscopy (초고압 동결장비와 초고압투과전자현미경을 이용한 초파리의 감간분체 형성과정의 구조분석)

  • Mun, Ji-Young;Arii, Tatsuo;Hama, Kiyoshi;Han, Sung-Sik
    • Applied Microscopy
    • /
    • v.37 no.1
    • /
    • pp.35-42
    • /
    • 2007
  • The late pupal stage of Drosophila melanogaster occurs immediately before the completion of retinal development, during which the rhabdomere rapidly forms. In this period, the photoreceptor cells were fixed and dehydrated using a high-pressure freezer (HPF) and freeze substitution (FS) technique, which is the most effective in preserving the cell structures, and observed using high-voltage electron microscopy (HVEM) at 1000 KV. The rhabdomere was classified structurally into three types of formation patterns using stereo-tiling image of thick sections. Initially, hexagonal arrays of rhabdomere existed in different angles. In addition, small pieces of rhabdomere could be observed in the cytoplasm of the photoreceptor rolls, which were visible during the profess of rhabdomere formation. In addition, multiple layers of rhabdomere strings were observed. We observed there are at least three types of vesicles related to rhabdomere formation in photoreceptor cells. In addition, it was found that these vesicles initiate the formation of the rhabdomeres during the pupal stage. Collectively, these data suggest that rhabdomeres were mainly formed through vesicles, and that parts of the rhabdomere formed first and then gathered and formed rhabdomeres in the late pupal stage.

Ultrastructures of Ptilota filicina (Rhodophyta) by High Pressure Freezing(HPF): Comparison of HPF Fixation and Chemical Fixation (High Pressure Freezing (HPF)을 이용한 조류 Ptilota filicina의 미세구조 관찰:HPF 고정법과 화학 고정법의 비교)

  • Lee, Sang-Hee;Kim, Youn-Joong;Jeong, Jong-Man;Kim, Jin-Gyu;Kim, Young-Min;Kweon, Hee-Seok;Moon, Won-Jin;Lee, Seok-Hoon
    • ALGAE
    • /
    • v.21 no.4
    • /
    • pp.479-483
    • /
    • 2006
  • In preparation of the biological samples for electron microscopy, the chemical fixation by glutaraldehyde, paraformaldehyde, and OsO4 has been generally used for a long time. However, the chemical fixation method has some problems: the infiltration time is a little bit long and the ultrastructure of cell or tissue transforms before complete fixation of sample. So, recently, cryo-fixation is considered more often in biomedical field. In this study, we compared High Pressure Freezing (HPF) method with chemical fixation method using a algal sample (Ptilota filicina J. Agardh), which was difficult to fix using chemical fixation method. In chloroplast, the ultrastructure of thylakoid lamella and phycobilisome can not show clearly by chemical fixation. In this study we could observe the ultrastructure of thylakoid lamella and phycobilisome of chloroplast very clearly using HPF fixation. An improved images of ultrastructures of nucleus, mitochondrion and floridean starch could obtain. These results suggest that HPF method is very useful method in algal specimen for electron microscopy.