A Sertoli cell (a kind of sustentacular cell) is a "nurse" cell of the testicles that is part of a seminiferous tubule and helps in the process of spermatogenesis; that is, the production of sperm.
It is activated by follicle-stimulating hormone (FSH) secreted by the adenohypophysis, and has FSH receptor on its membranes. It is specifically located in the convoluted seminiferous tubules (since this is the only place in the testes where the spermatozoa are produced). Development of Sertoli cells is directed by the testis-determining factor protein.
The answer is B (400 j) because 10% gets taken off so it would go from 4,000 to 400 then to 40
D. radial symmetry evolved at least twice in unrelated invertebrates groups
