Fig. 3From: Morphology, mating system and taxonomy of Volvox africanus (Volvocaceae, Chlorophyceae) from ThailandTransmission electron microscopy of asexual spheroids of Volvox africanus G.S. West strain 1101-NZ-11 from Thailand. A–C Whole spheroid is surrounded by a tripartite layer (colonial boundary) of the extracellular matrix (arrows). Each protoplast is enclosed tightly by a thin layer (cellular envelope) of the matrix (arrowheads) and has a nucleus (N) and a chloroplast (c) with a pyrenoid (p). Note that the matrix between cells forms individual sheath (asterisks). A Section of peripheral region showing cells and extracellular matrix. B Details of cellular envelopes. C Longitudinal section of a cellBack to article page