morula

morula egg cell embryo development zygote vector pregnancy biology sperm ovule blastula 4cell anatomy gastrula blastomeres embryonic cage child birth cytoplasm division embryology endoderm female fertility fertilization fetus follicle genes gynecology health human infertility insemination medical medicine microscopic natural oocyte ovary ovulation penetrate reproduction reproductive seed stage fertilized treatment morula solid ball contained zona pellucida segmentation ovum embryo