Developing sperm cells are protected by a blood-testis barrier formed by
A. sustentacular cells.
B. interstitial spaces.
C. leukocytes.
D. Leydig cells.
E. connective tissue septa.
Answer: A
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The spinous process has a bifid tip in most ________ vertebrae.
A. coccygeal B. thoracic C. cervical D. lumbar E. sacral
Label the fibrous capsule and synovial membrane of this joint
What will be an ideal response?
Drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. How do you suppose these drugs work?
A. They prevent calcium from entering cardiac muscle, thus slowing down the heart rate. B. They prevent calcium from entering the sarcoplasmic reticulum of smooth muscle. C. They stimulate the calcium pump in smooth muscle, thus removing calcium from the calmodulin. D. They prevent calcium from entering smooth muscle, thus allowing the muscle to relax. E. They prevent calcium from exiting the sarcoplasmic reticulum in skeletal muscle.
Tell how a carcinogen can cause cancer, and describe the progression of cancer