Are you interested in more precise information? Water Bear web base is
intended to be a popular magazine, nevertheless we might peep over to the real
scientists for a moment. Much of the knowledge at hand today has been available
already about 100 years ago. As an example we might choose a short text block
published in 1936 by the famous Berlin tardigrade specialist Ernst Marcus.
There are a lot of scientific terms included and it might be helpful to have
some of your biology school textbooks at hand before beginning. I have
worked hard to translate all this from German and I hope that the contents
are still there:
"Egg formation proceeds by means of nutrimentation by abortive egg cells.
The ovary endothelium forms a chorion as an egg shell. It is important for
taxonomic reasons to know whether the egg shell is smooth or has so-called
egg processes (typical for the genus Macrobiotus).
Adequate furrowing proceeds irregularily by phase difference.
The diploid chromosome number ranges from about 10 to 14.
Gastrula formation is performed by endoblastic delamination.
Gametes can be seen at first within the primary entoderm. By folding away from
the archenteron 5 metamere pairs of coelom containers are formed.
The first four pairs of those coelom containers dissolve and produce
muscles and storage cells. The fifth pair forms the gonades and the
gonade tubes. The stomadeum including stylets and the muscles of the buccal
tube, buccal glands, intestinal glands, proctadeum, claw formation glands
and the nervous system which is split off from the epidermis, are all ektodermal.
The middle part of the intestine is entodermic. The extremities are
processes of the body wall."
(Ernst Marcus: Tardigrada. p. 14. Berlin 1936)
Now you have encountered a poor translation from the German original
by the author of the Water Bear web base magazine.
So, possibly you were not able to understand everything in detail. Nevertheless
this example should have helped to make clear that tardigrade egg development investigation
was on a high level already in the first half of the 20th century. You can even go back
further on the timeline and find several series of colour prints of tardigrade
egg cross sections in the professional literature as early as in the late 19th century!
It is a pity that those splendid works have been superseeded by time and cannot
be found any more in modern bibliographies.