Starfish early cleavage divisions Blastomeres

Starfish gastrulation Ectoderm Blastopore Blastopore Archenteron Archenteron Endoderm Endoderm Ectoderm Blastomeres Blastomeres Blastocoel Blastocoel Blastocoel Blastocoel Blastocoel Blastomeres

Frog embryo development Endoderm Ectoderm Gastrulation begins Blastocoel Blastocoel Vegetal pole Animal pole Blastomere Blastomere

Chick embryo development Optic vesicle Cranial neuropore Heart Somites Neural tube/spinal cord Foregut Neural tube/spinal cord Heart Forebrain Eye Blood vessels Somites Somites Neural tube/spinal cord Neural folds Cranial neuropore

Human early embryo Corpus luteum Blastocyste implants in the uterus wall Blastocyst reaches the uterus Morula Cleavage divisions Secondary oocyte meets with a sperm Secondary oocyte enters the infundibulum Released secondary oocyte Ovlating Graafian follicle Follicular developmental stages Uterus

Human late development Umbilical cord Placenta Cervix Vagina Vagina Vagina Vagina