Tracking life's first step: Two molecules 'awaken' brand new genome

Within hours after fertilization, a unique genome forms from chromosomes contributed by the egg and sperm. However, this new genome is initially inactive and must be "awakened" to begin the transcription of its DNA and start ...

Embryo

An embryo (irregularly from Greek: ἔμβρυον, plural ἔμβρυα, lit. "that which grows," from en- "in" + bryein "to swell, be full"; the proper Latinate form would be embryum) is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination. In humans, it is called an embryo until about eight weeks after fertilization (i.e. ten weeks LMP), and from then it is instead called a fetus.

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