Only for those groups have scientists almost completely identified all the world's species. Biologists have yet to describe many species of plants, invertebrate animals and lichens. So the number of these species known to science increases substantially every year.
The interglandular tissue is also increased in quantity, and is crowded with large round, oval, or polygonal cells, termed decidual cells. Their enlargement is due to glycogen and lipid accumulation in the cytoplasm allowing these cells to provide a rich source of nutrition for the developing embryo.rom Wikipedia, the free encyclopedia. Before the fertilized ovum reaches the uterus, the mucous membrane of the body of the uterus undergoes important changes and is then known as the decidua.
The sperm of decapods have been divided into two basic morphological groups: (1) reptantian type (crab, lobster and crayfish) characterized by a membrane-limited nucleus with uncondensed chromatin, nuclear spikes containing microtubules, a complex acrosome, and a membrane lamellar region; and (2) natantian type (shrimp and prawns) with only one spike that is thought to be originating from the acrosome, and a nucleus which is not membrane bound (Dudenhausen and Talbot, 1982).