Final answer:
The reproductive structure of Coccidioides immitis is known as a spherule, which differentiates and fills with endospores causing coccidioidomycosis or Valley fever.
Step-by-step explanation:
The reproductive structure of Coccidioides immitis is called a spherule. This organism is known to cause coccidioidomycosis, which is sometimes referred to as Valley fever. Coccidioides immitis differentiates into spherules that are filled with endospores once inside the body.
Most infections are asymptomatic and self-limiting, but can be serious for immunocompromised patients. The disease is prevalent in certain areas such as the San Joaquin Valley of California and other semi-arid regions of the southwestern United States, Mexico, and Central and South America.