An Electron-Microscopic Study of the Starch-Containing Plastids in the Fern Todea Barbara

1969 ◽  
Vol 4 (1) ◽  
pp. 211-221
Author(s):  
H. M. SMITH ◽  
D. S. SMITH
Keyword(s):  
Microscopic Study ◽  
Electron Microscopic Study ◽  
The Other ◽  
Morphological Development ◽  
Electron Microscopic ◽  
Physiological Differences

Gametophytes of Todea barbara grown in vitro have two types of starch-containing plastids. The first type are chloroplasts having well-developed grana regions connected by intervening membranes and little deposition of starch. The other type are amyloplasts usually containing abundant starch deposits and stacks of membranes which resemble the grana of the chloroplast but are not connected. Even when little starch is present, the latter type has very few internal membranes. Membrane spacing and gross organization of the mature plastid of both types suggests similar morphological development. However, when and where in this development known physiological differences arise is not yet known.

Some Mitochondrial Changes in Denervated Muscle

1968 ◽  
Vol 3 (1) ◽  
pp. 49-54
Author(s):  
R. MILEDI ◽  
c. R. SLATER
Keyword(s):  
Microscopic Study ◽  
Electron Microscopic Study ◽  
The Other ◽  
Muscle Fibres ◽  
Rat Diaphragm ◽  
Denervated Muscle ◽  
Electron Microscopic ◽  
Normal Appearance ◽  
Characteristic Picture

An electron-microscopic study was made of the mitochondria in normal and denervated rat diaphragm muscles. Two types of structurally different muscle fibres were found: one type had a well-defined M-line, while the other did not. The mitochondria in normally innervated muscle are regularly arranged at both sides of the Z-line. The mitochondria are very long and branched, and surround the myofibrils at the level of the Z-line. In transverse sections of the muscle fibres the worm-like mitochondria give a very characteristic picture. After denervation the mitochondria are smaller and less regularly arranged. In transverse sections of the muscle fibres the mitochondria have small circular profiles. This contrasts sharply with the normal appearance and makes it possible to distinguish normal from denervated fibres. The mitochondrial changes can be detected less than 24 h after denervation.

Sign in / Sign up

Export Citation Format

Share Document