When Life Begins
Here is what Encyclopedia Britannica says about the start of life, in an article written by leading embryologists:
Gastrulation and the formation of the three germinal layers is the beginning of the subdivision of the mass of embryonic cells produced by cleavage. The cells then begin to change and diversify under the direction of the genes. The genes brought in by the sperm exert control for the first time; during cleavage all processes seem to be under control of the maternal genes. In all cases of hybridization, in which indivduals from
different species produce offspring, the influence of the sperm is first apparent at gastrulation; paternal characteristics may appear at this stage; or the embryo may stop developing and die if the paternal genes are incompatible with the egg (as is the case in hybridization between species distantly related). (Encyclopedia Britannica, Macropedia, Growth and Development, Vol 20, page 394, col. 2, paragraph 1.)
Clearly, whoever is telling the Catholic Bishops that life begins at conception is unfamiliar with this information. If ensoulment is necessary for the development of the child, clearly a human soul cannot be there until after Gastrulation. For those who read this column who are in a position to enlighten them, please share this passage and adivse them to look it up for themselves and follow the footnotes.