GC: n

S: AustLII – http://www.austlii.edu.au/au/legis/vic/num_act/rihea200874o2008393/s3.html (last access: 16 May 2016); PGDCEM – http://www.pgdcem.com/en_index.html (last access: 16 May 2016).

N: 1. “fetus in utero at an early stage of development,” mid-14c., from Medieval Latin embryo, properly embryon, from Greek embryon “a young one,” in Homer, “young animal,” later, “fruit of the womb,” literally “that which grows,” from assimilated form of en “in” (see en- (2)) + bryein “to swell, be full.”
2. A new organism in the earliest stage of development. In humans this is defined as the developing organism from the fourth day after fertilization to the end of the eighth week. After that the unborn baby is usually referred to as the fetus. adj., adj em´bryonal, embryon´ic.
Immediately after fertilization takes place, cell division begins and progresses at a rapid rate. At approximately 4 weeks the cell mass becomes a recognizable embryo from 7 to 10 mm long with rudimentary organs. The beginnings of the eyes, ears, and extremities can be seen. By the end of the second month the embryo has grown to a length of 2 to 2.5 cm, and the head is the most prominent part because of the rapid development of the brain; the sex can be distinguished at this stage.
At the time of fertilization the ovum contains the potential beginnings of a human being. As cell division takes place the cells of the blastoderm (embryonic disk) gradually form three layers from which all the body structures develop. The ectoderm (outer layer) gives rise to the epidermis of the skin and its appendages, and to the nervous system. The mesoderm (middle layer) develops into muscle, connective tissue, the circulatory organs, circulating lymph and blood cells, endothelial tissues within the closed vessels and cavities, and the epithelium portion of the urogenital system. From the endoderm (internal layer) are derived those portions not arising from the ectoderm, the liver, the pancreas, and the lungs.
3. What Is The Difference Between An Embryo And A Fetus? Baby was an embryo and is now a fetus. What does that mean?
It’s a different phase of baby’s development. “The embryo is defined as the developing pregnancy from the time of fertilization until the end of the eighth week of gestation, when it becomes known as a fetus,” says James A. O’Brien, MD, ob-gyn, medical director of inpatient obstetrics at Women & Infants Hospital of Rhode Island.
During the embryonic period, cells begin to take on different functions. The brain, heart, lungs, internal organs, and arms and legs begin to form. Once baby is a fetus, it’s more about growth and development to prep for life on the outside.

S: 1. OED – http://www.etymonline.com/index.php?term=embryo (last access: 16 May 2016). 2. TFD – http://medical-dictionary.thefreedictionary.com/embryo (last access: 16 May 2016). 3. TBump – http://www.thebump.com/a/difference-between-embryo-and-fetus (last access: 16 May 2016).

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CR: ectopic pregnancy, fetus, midwife, pregnancy.