yolk sac
Egg's nutrient pouch
A yolk sac is the membranous pouch attached to an embryo that contains yolk—nutrients that sustain the developing organism before other feeding mechanisms take over.
In egg-laying animals, it provides food until hatching.
In mammals, including humans, the yolk sac forms early in pregnancy and performs temporary functions like early blood cell production before the placenta develops.
Fetal enclosing membrane
- chorionOuter embryonic membrane
- blastocystEarly developmental stage before implantation
- embryogenesisFormation of early life
- gastrulationEmbryo forms primary layers
ectoderm · mesoderm · endoderm · organogenesis · morphogenesis · fetus · umbilical cord · placenta
Gamete fusion creating zygote
- zygoteFirst embryonic cell
- ovumFemale reproductive cell
- eggReproductive cell in shell
- gestationCarrying offspring in womb
incubation · oviparous · viviparous · amniotes · vertebrates · spawning · clutch · hatchling
Vital dietary substances
- nourishmentFood that sustains life
- lipidsWater-insoluble biomolecules
- proteinsAmino acid polymers
- glucosePrimary cellular fuel
amino acids · absorption · sustenance · provision · energy · vitamins · minerals · fats
Oxygen-carrying blood cells
- red blood cellsOxygen-transporting components of circulation
- hemoglobinErythrocyte's oxygen-binding protein
- angiogenesisFormation of new vessels
amnion
Fetal enclosing membrane
- chorionOuter embryonic membrane
- blastocystEarly developmental stage before implantation
- embryogenesisFormation of early life
gastrulation · ectoderm · mesoderm · endoderm · organogenesis · morphogenesis · fetus · umbilical cord · placenta · gestation
fertilization
Gamete fusion creating zygote
gestation · incubation · oviparous · viviparous · amniotes · vertebrates · spawning · clutch · hatchling · brood
nutrients
Vital dietary substances
- nourishmentFood that sustains life
- lipidsWater-insoluble biomolecules
- proteinsAmino acid polymers
glucose · amino acids · absorption · sustenance · provision · energy · vitamins · minerals · fats
erythrocytes
Oxygen-carrying blood cells
- red blood cellsOxygen-transporting components of circulation
- hemoglobinErythrocyte's oxygen-binding protein
- angiogenesisFormation of new vessels
- Blood Systemblood, blood cells, red blood cells, white blood cells, platelets
- childbirth anatomyuterus, womb, placenta, umbilical cord, cervix
- Early Pregnancyconception, implantation, positive test, pregnancy test, embryo
- egg biologyegg, eggshell, egg white, white, albumen
- sacspouch, bladder, vesicle, bursa, cyst
- vestigial structuresappendix, coccyx, tailbone, wisdom teeth, plantaris