Die Embryonalentwicklung der Paradiesschnecke ... - TOBIAS-lib

Kapitel 2
three times for 10 min with 70% ethanol containing one drop of 32% NH 3 ,
dehydrated in a graded series of ethanol (70, 80, 90, 96, and 100%, three
times for 10 min each) and embedded in Technovit (Heraeus Kulzer, Germany).
An automatic microtome (2050 Supercut, Reichert-Jung, Germany)
was used to cut serial sections of 2- to 5-µm thickness, which were mounted
on microscope slides and stained with hematoxylin/eosin or methylene blue.
The slides were covered with Histokitt (Roth, Germany) and examined and
photographed with a light microscope (Axioskop 2, Zeiss, Germany). GIMP
was used for image editing (converting, scaling, rotating, white balancing,
color adjustment, and sharpening). Some SEM-images were vectorized with
Inkscape and these scetches were then inserted into the pictures. Labeling
was also done with Inkscape.
Results
The “normal” development will only be described briefly (for more detailed
descriptions see Demian and Yousif, 1973a–d, 1975) and compared to the
embryonic development under the influence of platinum. To make comparisons
easier, we used the terminology and abbreviations that were introduced
by Demian and Yousif (1973a) and added some new ones to better describe
the anatomy of platinum 2+ (Pt 2+ )-exposed snails. In this context, the term
“rudimentary shell gland” indicates the tissue that is in fact the common
anlage of the mantle and the shell gland, which spread over the visceral sac
in control snails.
In Stage VI (according to the classification by Demian and Yousif (1973a,c))
the rudimentary shell gland has bulged up and its peripheral cells form a
thickened ridge that will develop into the adult’s shell gland. For this circular
thickening the term “shell gland” is used. This nomenclature deviates
from Eyster (1986) and Kniprath (1977) who both used the term “shell field”
for the whole shell-secreting tissue and the term shell gland for the invaginated
shell field only.
The central, bulged up part of the rudimentary shell gland that is encircled
by the shell gland will develop into the outer mantle epithelium and will be
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