"Materials and Methods

The tests were carried out on male rats of the VEB Versuchstierproduktion Schonerlinde. The body weights (KG) were between 220-280 g at the beginning of the experiment. The age of the animals at this time varied between 8-10 weeks. The animals were housed in plastic cages (50x30x17 cm) on wooden spans. Temperatures in the non-air-conditioned rooms, averaged over several years, were 20± 2°C and relative humidity varied between 57-75% with the same averaging. Feed (pellets of VEB KIM Mischfutterwerk, variety R 13) and tap water ad lib.

The experimental approach included the following groups:

C (control): 5 ml application medium (solution mixture of 1.2-propanediol and aqua dest[ZM1] , (1:1 v/v) kg bw by gavage;

S (substance group[ZM2] ): EU, dissolved in the application medium (5 ml kg bw) by gavage. For dose levels, see information in the text.

Number of animals per group for all studies listed below n=10, for electron microscopy n=2.

Histology

The following colors and reactions were examined on 5 um thick kerosene sections fixed with formol (for PAS Gendre): HE, van Gieson, PAS (McManus), FE (Turnbull).

Histometric

Determination of mean parenchymal cell, nuclear, and endothelial volumes by the hit method (Lamprecht 1954; Haug 1962; Leibnitz 1964 [ocular grid square with 121 hit points (without periportal field) of the left hepatic lobe. Disbursement of hepatic cell nuclei and endothelial cells, of double nuclear cells as well as mitoses in the grid square. For each animal, 10 such squares were sampled, from which the mean values and their standard deviations were calculated. Number of liver cells = number of nuclei minus number of double nuclear cells.

Nucleus diameter calculated according to Hennig (1957).

Nucleus volumes as approximation values calculated according to the formula of the sphere content.

In addition, 500 hepatocytes/animal in their greatest length and width and the diameter of 1000 hepatocyte nuclei/animal 9 after single EU administration as well as the same number in corresponding control animals were measured by means of ocular band micrometers at 630x magnification.

Histoantoradiography

Immediately after substance administration i.v. application of 200-u Ci-tritium-thymidine in 0.5 ml physiological saline/animal (specific activity 7.0 Ci/mmol, UVVVR Prague). Death of animals after 24 h, exposure 4 weeks. Photo emulsion K 6 of VEB Filmfabrik Wolfen. Coloration: nuclear red. Disbursement of labeled nuclei (>10 silver nuclei) from 2000 hepatocyte nuclei/animal, integrated over the entire liver lobule, at 630x magnification. Labeling indices converted to 1000 nuclei/liver/animal.

Statistical analysis of the results using Student's t-test. Significance limit p < 0.05.

Electron Microscopy

For electron microscopy studies, tissue specimens were fixed in 1% osmium solution buffered in cacodylate and embedded in micropal. Images were taken with an Elmiscope 1A (Siemens AG West-Berlin) at magnifications of 10000- and 20000-fold."

[ZM1]Distilled water

[ZM2]Treatment group

Male Rats