microsphere

A microscopic spherical organism: applied by Cohn to the micrococci found in vaccine lymph and in small-pox pustules.

In the calcareous Foraminifera, the small primordial chamber of the test: an index of the dimorphism expressed by these bodies, as with like exteriors some have a microsphere and others a large primordial chamber or megasphere.

In cytology, the central portion of the astrosphere in the dividing cell. The center of the microsphere is occupied by the centrosome.

Any sphere whose size is measured in micrometres