Disector counting of synaptic bodies on TEM sections of the pineal gland using a correlation factor increasing effectiveness
M. Hainz, H. Jastrow, M.-A. von Mach and L. Vollrath
Anatomisches Institut der J. Gutenberg-Universität Mainz, Becherweg 13, D-55128 Mainz

Synaptic bodies (SBs) are electron-dense structures of pinealocytes, photoreceptor- and hair-cells surrounded by synaptic vesicles. SB profiles appear as tiny rods (~ 200 x 35 nm) requiring investigation at x 20.000 (transmission electron microscope). The mostly plate-like SBs undergo changes in number and size. Therefore they were quantified by the disector, which, in contrast to counts in a standard area, is not influenced by varying shape and size of particles expressing their number per volume. Due to their rareness tissue areas overlaying more than 10 TEM screens have to be scrutinised just to find one profile. Since application of the disector requires scrutinising 2 serial sections simultaneously this method markedly increases time of evaluation in contrast to counts on a single section. To improve effectiveness a proportion factor has been introduced for specimens of each experimental group. This factor results from the relation of SB-profile number and the amount of SBs determined once by the disector for each group. Thus counting of SB-profiles allows calculation of SB-numbers per volume for other animals of an identically treated group after using the disector on one specimen of the latter. Thus the overall examination time is reduced by more than 50%. Chicken and rat pineal gland were examined using these two methods. Profile counts were performed on areas >20.000 ?m2 in the same tissue that was evaluated by the disector. Based on the data obtained, a conversion factor of 2.98 / 3,2 for the chicken / rat pineal gland was found. The reliability of this conversion factor is discussed.

This poster was presented at the 14th Meeting of the Anatomical Society at Würzburg, Germany, 1-3 October 1997, poster No. 68. 

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