Shape and position of the sarcoplasmic reticulum and the Golgi apparatus in the sole plate and remaining subsarcolemmal muscle region of the mouse using imidazole-osmium staining

The transillumination possibility of imidazole-osmium postfixed tissue and its consequences for the handling of tissue samples

Osmium postfixation is established as a routine procedure for transmission electron microscopy (TEM). On the one hand, this routine procedure leads to good results for TEM, but on the other hand results in blackened tissue samples that do not allow examination of any structures within the embedded tissue sample by a light microscope. Equivalent fixation results for TEM are achieved with imidazole-osmium postfixation, and with this postfixation method tissue is not blackened and can be transilluminated with point light sources. This allows easier recognition of histological details within tissue samples and makes it possible to screen embedded samples for appropriate ultrastructural processing. Jejunum is used to demonstrate the method.

About the morphological relationships of the sarcoplasmic reticulum in the sole plate area of the frog

In the present investigation the sole plate area of motor end plates of the frog is ultrastructurally examined with different postfixation methods. We concentrated in this case on the proof of the smooth and rough sarcoplasmic reticulum of the sole plate. The relations of the smooth and rough sarcoplasmic reticulum to subsynaptic folds and the local T-system and its connections to diads and triads in the sole plate area are represented. The morphological differences between mammal and frog are pointed out. The possible functions of the sarcoplasmic reticulum in the myofibril-free sarcoplasm are discussed.

The transillumination possibility of imidazole-osmium postfixed muscle tissue and its consequences for the handling of muscle tissue samples

The osmium postfixation of tissue leads to good results for transmission electron microscopy, but also produces completely blackened tissue samples that do not allow the recognition of internal structures. With imidazole-osmium postfixation, one achieves comparable results in high electron microscopic resolution as with routine osmium postfixation. But the tissue samples are not blackened and can, therefore, be transilluminated with point light sources. The new postfixation technique makes it possible to recognize histological details such as vessels, nerve fibers, and the cross-banding pattern in an untrimmed block. This makes it possible to screen-embedded tissue samples for appropriate ultrastructural processing.