zygote 2-cell stage. human embryonic development.

anatomy biology birth blastomeres cage cell conceiving cytoplasm developing development diploid division egg embryo embryology embryonhuman embryonic female fertility fertilization fertilized fetus follicle form fusion gametes genes genetic gynecology health human illustration illustrationn infant infertility insemination kernel medical medicine merger microscopic natural nhaploid nucleus oocyte ovary ovulation ovule ovum penetrate plasma pregnancy rendering reproduction reproductive seed segmentation sexual sperm stage system treatment two unnatural vitro zygote