I’ve written several times about the process of inversion that occurs during the development of algae in the family Volvocaceae. Today I was going through a paper I’d read (and even written about) before, and I came across a turn of phrase I appreciated regarding inversion:
The fully cleaved embryo contains all of the cells of both types that will be present in an adult but it is inside out with respect to the adult configuration. This awkward condition is quickly corrected by a gastrulation-like inversion process.
The quote is from Benjamin Klein, Daniel Wibberg, and Armin Hallmann’s 2017 paper, “Whole transcriptome RNA-Seq analysis reveals extensive cell type-specific compartmentalization in Volvox carteri.” Setting aside that animal gastrulation and Volvox inversion may not be as similar as they are often portrayed, I love the description of inside-out colonies as “awkward”. As if they just realized they left the house with their shirt half tucked in and inversion is their way of saying “Excuse me while I get myself sorted out here.”
Inversion video provided by Stephanie Höhn:
Klein, B., D. Wibberg, and A. Hallmann. 2017. Whole transcriptome RNA-Seq analysis reveals extensive cell type-specific compartmentalization in Volvox carteri. BMC Biol. 15:111. BMC Biology. DOI: 10.1186/s12915-017-0450-y