Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
, 43 (6), 621-31

Volvox Carteri as a Model for Studying the Genetic and Cytological Control of Morphogenesis

Affiliations
Review

Volvox Carteri as a Model for Studying the Genetic and Cytological Control of Morphogenesis

D L Kirk et al. Dev Growth Differ.

Abstract

The green alga Volvox carteri has a very simple and regular adult form that arises through a short sequence of well-defined morphogenetic steps. A mature gonidium (asexual reproductive cell) initiates a stereotyped sequence of rapid cleavage divisions that will produce all of the cells found later in an adult. A predictable subset of these divisions are asymmetric and result in production of a small set of germ cells in a precise spatial pattern. Throughout cleavage, all intracellular components are held in predictable spatial relationships by a cytoskeleton of unusually regular structure, while neighboring cells are also held in fixed spatial relationships by an extensive network of cytoplasmic bridges that form as a result of incomplete cytokinesis. As a result of these two orienting mechanisms combined, dividing cells are arranged around the anterior-posterior axis of the embryo with precise rotational symmetry. These relationships are maintained by the cytoplasmic bridge system when the embryo that was inside out at the end of cleavage turns right-side out in the gastrulation-like process of inversion. Inversion is driven by a cytoskeleton-mediated sequence of cell shape changes, cellular movements and coordinated contraction. Then, by the time the cytoplasmic bridges begin to break down shortly after inversion, a preliminary framework of extracellular matrix (ECM) has been formed. The ECM traps the cells and holds them in the rotational relationships that were established during cleavage, and that must be maintained in order for the adult to be able to swim. Transposon tagging is now being used to clone and characterize the genes regulating these morphogenetic processes.

Similar articles

See all similar articles

Cited by 19 PubMed Central articles

See all "Cited by" articles

LinkOut - more resources

Feedback