The phrase "spherical structures" refers to objects or buildings that have a shape or form of a sphere, which is a perfectly round object like a ball. Full definition
Two metal shutters at one end of a large building on the summit slide apart like the lids of a waking dragon, revealing a squat, almost spherical structure of steel and glass. (discovermagazine.com)
These molecules repel water at one end and attract it at the other, properties that cause them to self - assemble into spherical structures, which can encapsulate large payloads of biological molecules. (scientificamerican.com)
The team then carefully inserted mouse follicles — spherical structures containing a growing egg surrounded by hormone - producing cells — into these «scaffolds.» (sciencemag.org)