11-Letter Words Starting: TRO

• a sporozoan in the active feeding stage of its life cycle

• The free-swimming larva of some invertebrates that have a circlet of cilia

• the lowest atmospheric layer; from 4 to 11 miles high (depending on latitude)

• A protein involved in muscle contraction. It is related to myosin and occurs together with troponin in the thin filaments of muscle tissue.

• the membrane that forms the wall of the blastocyst in early development; aids implantation in the uterine wall

• type genus of the Troglodytidae