Freeze-fracture Scanning Electron Microscopy of Radial Keratotomy Incisions

1994 ◽  
Vol 117 (3) ◽  
pp. 399-401 ◽  
Author(s):  
Stephen A. Updegraff ◽  
Marguerite B. McDonald ◽  
Roger W. Beuerman
Author(s):  
M. Spector ◽  
A. C. Brown

Ion beam etching and freeze fracture techniques were utilized in conjunction with scanning electron microscopy to study the ultrastructure of normal and diseased human hair. Topographical differences in the cuticular scale of normal and diseased hair were demonstrated in previous scanning electron microscope studies. In the present study, ion beam etching and freeze fracture techniques were utilized to reveal subsurface ultrastructural features of the cuticle and cortex.Samples of normal and diseased hair including monilethrix, pili torti, pili annulati, and hidrotic ectodermal dysplasia were cut from areas near the base of the hair. In preparation for ion beam etching, untreated hairs were mounted on conducting tape on a conducting silicon substrate. The hairs were ion beam etched by an 18 ky argon ion beam (5μA ion current) from an ETEC ion beam etching device. The ion beam was oriented perpendicular to the substrate. The specimen remained stationary in the beam for exposures of 6 to 8 minutes.


HortScience ◽  
2000 ◽  
Vol 35 (1) ◽  
pp. 99-103 ◽  
Author(s):  
Hirofumi Terai ◽  
Alley E. Watada ◽  
Charles A. Murphy ◽  
William P. Wergin

Structural changes in chloroplasts of broccoli (Brassica oleracea L., Italica group) florets during senescence were examined using light microscopy, scanning electron microscopy (SEM) with freeze-fracture technique, and transmission electron microscopy (TEM) to better understand the process of chloroplast degradation, particularly at the advanced stage of senescence. Light microscopy revealed that chloroplasts, which initially were intact and green, became obscure in shape, and their color faded during senescence. Small, colored particles appeared in cells as the florets approached the final stage of senescence and became full- to dark-yellow in color. Scanning electron microscopy showed that stroma thylakoids in the chloroplast initially were parallel to each other and grana thylakoids were tightly stacked. As senescence advanced, the grana thylakoids degenerated and formed globules. The globules became larger by aggregation as senescence progressed, and the large globules, called “thylakoid plexus,” formed numerous vesicles. The vesicles ultimately were expelled into the cytosol, and the light microscope revealed many colored particles in the senescent cells. These results indicate that the degradation of chloroplasts in broccoli florets progresses systematically, with the final product being colored particles, which are visible in yellow broccoli sepal cells.


Author(s):  
S. R. Bawa ◽  
H. K. Bains

Associations amongst spermatozoa have been reported in a variety of vertebrate and invertebrate animals. Spermatozoa come together and are attached to each other only in the region of the head, their tails are free – required to steer the spermatozoa. We have studied sperm-sperm association in squirrel using electron microscopy.Small pieces of epididymides of adult squirrels (Funambulus pennanti) were fixed in cacodylate buffered glutaraldehyde and processed in a conventional manner for transmission and scanning electron microscopy Ultrathin sections and freeze-fracture replicas were examined with JEOL 1200 EX electron microscope.


Author(s):  
Orlando J. Castejón

Conventional and high resolution scanning electron microscopy have been applied to trace short cerebellar nerve circuits and to explore the outer and inner surfaces of spine, glomerular and axodendritic synapses. Samples of teleost fishes (Arius spixii and Salmo Trutta) cerebellar cortex were processed according to the slicing technique for conventional scanning electron microscopy (SEM), ethanol cryofracturing technique and freeze-fracture scanning electron microscopy (FFSEM) (Castejón, 1988). Primate (Rhesus monkey) cerebellar cortex was processed for high resolution scanning electron microscopy (Castejón and Apkarian, 1990), according to the protocol of delicate specimen preparation (Peters, 1980). Observations were made in JEOL 100B with (ASID), scanning attachment ISI DS-130 equiped with LaB6 emitter and Hitachi S-900 SEM with a cold cathode field emitter. Micrographs for HRSEM were soft focus printed to reduce instrumental noise (Peters, 1985). A comparison was made of gold-palladium and chromium coating cerebellar samples.The slicing technique and the cryofracture process exposed the neuronal outer surface revealing hidden surface ensheathed by neuroglial cells.


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