The embryonic development of the malacostracan crustacean Porcellio scaber (Isopoda, Oniscidea)

Abstract

To examine the evolution of development and put it into a phylogenetic context, it is important to have, in addition to a model organism like Drosophila, more insights into the huge diversity of arthropod morphologies. In recent years, the malacostracan crustacean Porcellio scaber Latreille, 1804 has become a popular animal for studies in evolutionary and developmental biology, but a detailed and complete description of its embryonic development is still lacking. Therefore, the embryonic development of the woodlouse P. scaber is described in a series of discrete stages easily identified by examination of living animals and the widely used technique of nuclei staining on fixed specimens. It starts with the first cleavage of the zygote and ends with a hatched manca that eventually leaves the mother's brood pouch. Classical methods like normal light microscopy, scanning electron microscopy and fluorescence microscopy are used, in addition to confocal LCM and computer-aided 3D reconstruction in order to visualise important processes during ontogeny. The purpose of these studies is to offer an easy way to define the different degrees of development for future comparative analyses of embryonic development amongst crustaceans in particular, as well as between different arthropod groups. In addition, several aspects of Porcellio embryonic development, such as the mouth formation, limb differentiations and modifications or the formation of the digestive tract, make this species particularly interesting for future studies in evolutionary and developmental biology.

Embryonic development and staging of the cobweb spider Parasteatoda tepidariorum C. L. Koch, 1841 (syn.: Achaearanea tepidariorum; Araneomorphae; Theridiidae)

“…This is a common feature in arthropod development (e.g. Manton 1949;Larink 1969;Wolff 2009). In spiders, the region of the blastopore becomes slightly elevated, and the terminology changes from the earlier blastopore to the later primary thickening (stage 4).…”

“Crustacea”: Comparative Aspects of Early Development

“…For amphipods and isopods, it has been shown that gene expression is linked to cell lineage and that defi ned cells of the grid express the gene distal -less responsible for the outgrowth of limbs . Furthermore, it has been shown that throughout limb development, individually identifi able cells from the ectodermal grid are responsible for the formation of specifi c limb parts such as the different limb branches endopodite and exopodite (Wolff andScholtz 2006 , 2008 ). Limbs of different morphology have their origin in a defi ned set of serial homologous cells coming from the grid.…”

“…A broader view on patterns of cell division in crustaceans uses the notion of stereotypic cell divisions that refers to divisions that are identical in timing, size, and location that can be detected in cases when the fate of the cells and their respective contribution to the germ layers is unknown (Alwes and Scholtz 2004 ;Klann and Scholtz 2014 ). Stereotypic divisions might even apply to cases where cleavage is superfi cial (Wolff 2009 ;Alwes and Scholtz 2014 ). This classifi cation is discussed for the cladoceran Leptodora and for the Euphausiacea and for the similarities between Euphausiacea and Dendrobranchiata (Samter 1900 ;Alwes and Scholtz 2004 ).…”

An evolutionary solution of terrestrial isopods to cope with low atmospheric oxygen levels

“…Because the same hatchling size was attained, we infer that processes that govern completion of intramarsupial development might be differentially affected by oxygen availability during the two marsupial phases; any effect during the aquatic phase may be compensated for during the gaseous phase. At present, we can only speculate about potential constraints leading to the ratio between the two phases, such as growth and development of the digestive system, cuticular protuberances or the tubular heart (Milatovičet al, 2010;Mrak et al, 2014;Štrus et al, 2008;Wolff, 2009). …”