_____ surround the spermatids and immature sperm until they are released into the lumen of the seminiferous tubule; they provide it with nutrition, guide its movements, and secrete the testicular fluid which provides nutrients and growth signals.

3000+ review questions on anatomy and physiology. 

Anatomy refers to the internal and external structures of the body and their physical relationships, whereas physiology refers to the study of the functions of those structures.