14.Among the most important are the sertoli cells inside the tubes, which nourish developing sperm cells, sort of like how female follicle cells help oocytes.
18.Some of the only parts of the body whose motions aren't governed by the muscular system are sperm cells, the hair-like cilia in our airways, and certain white blood cells.
19.First, they all start as single-celled zygotes — made from a sperm cell and egg cell combo — that become multicellular embryos: the tiny beginnings of roots, stems, and leaves.
20.We also know that they’re inherited, but for a long time, geneticists thought that sperm cells were too small to contain both the genome AND the epigenetic information of the donor.