The word "alaqah" refers to something that clings (like a leech or bloodsucker). This is an appropriate description of the human embryo from days 7-24 when it clings to the endometrium of the uterus, in the same way that a leech clings to the skin. Just as the leech derives blood from the host, the human embryo derives blood from the decidua or pregnant endometrium. It is remarkable how much the embryo of 23-24 days resembles a leech (Fig. 2). As there were no microscopes or lenses available in the 7th century, doctors would not have known that the human embryo had this leech-like appearance. In the early part of the fourth week, the embryo is just visible to the unaided eye because it is smaller than a kernel of wheat.
in Surah Alaq (the Clot - #96), it says people are created from "clots", hence the name of the surah.
however, a cursory study of Embryology, as offered by medical colleges, does not reveal any such thing. IIRC, the events are as follows:
spermatozoan meets ovum, binds the outside, fuses, and prevents any other spermatozoan from fertilizing the egg. the male DNA enters the female cell, and now you have a zygote which 6-9 days after fertilization (which itself occurs some 12-24 hours intercourse, IIRC), binds to endometrial lining, and 9 months or 37-41 weeks later, a bundle of joy pops out.
but when i was leafing through Langeman's Embryology textbook, i found the mentioning of a clot of blood at some point, which was quite mind boggling.