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.
The shell is created by calcium deposition around the forming egg within the uterus. The fertilized ova takes approximately 4 hours to travel to the uterus. Once in the uterus, calcification of the egg's shell takes approximately 20 hours. This is why a hen can only lay one egg per 24 hour period. About 15 minutes after the first egg is laid, the hen ovulates again and the process is repeated.