Freebase(0.00 / 0 votes)Rate this definition: Ibid. Ibid. is the term used to provide an endnote or footnote citation or reference for a source that was cited in the preceding endnote or footnote. This is similar in meaning to idem, abbreviated Id., which is commonly used in legal citation. To find the ibid. source, one must look at the reference preceding it. Anagrams for ibid. Â»
Fertilization and Embryo Development. Following ovulation, the egg is capable of fertilization for only 12 to 24 hours. Contact between the egg and sperm is random. Once the egg arrives at a specific portion of the tube, called the ampullar-isthmic junction, it rests for another thirty hours. Fertilization â sperm union with the egg â occurs in this portion of the tube. The fertilized egg then begins a rapid descent to the uterus.
Fertilization: Sperm Penetrates Egg. It takes about 24 hours for a sperm cell to fertilize an egg. When the sperm penetrates the egg, the surface of the egg changes so that no other sperm can enter.At the moment of fertilization, the baby's genetic makeup is complete, including whether it's a boy or girl.he Sperm's Long Journey. A man may ejaculate 40 million to150 million sperm, which start swimming upstream toward the fallopian tubes on their mission to fertilize an egg. Fast-swimming sperm can reach the egg in a half an hour, while others may take days. The sperm can live up to 48-72 hours.