The time period during which an organ is coming ""on-line"" during pre-natal development is referred to as the:

Embryonic period

Explanation:

During Prenatal development, the development of an organism takes place in three stages  

1)Stage I – When the organism is at the stage I i.e the germinal stage a zygote is formed after a sperm fuses with an egg. The mass of cell move through the fallopian tube and gets embedded in the uterus wall. This process is called implantation.  

2)Stage II – In the second stage i.e Embryonic Stage major organs start developing and come in line. After this stage, the embryo is one inch long.  

3)Fetal stage – Sex organ, bone, muscle start forming.  

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the dead sea, the lowest place on earth at 430 metres (1,410 ft) below sea level, has a correspondingly high typical atmospheric pressure of 1065 hpa.

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