1. Membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional
   - yolk sac, vitelline sac, umbilical vesicle

Type of: sac

• diminutive
• diminutiveness
• dimit
• dimity
• dimly
• dimmed
• dimmer
• dimmer switch
• dimness
• Dimocarpus
• Dimocarpus longan
• dimorphic
• dimorphism
• Dimorphotheca
• dimorphous
• dimout
• dimple
• dimpled chad
• dimply
• dimwit
• din
• Din Land
• dinar
• Dindymene
• dine