By the time of implantation in uterine endometrium the typical feilized ovum is divided into how many cells

Implantation is the attachment of the blastocyst to the endometrium, and its subsequent embedding in the compact layer, occurring 6-7 days after feilization of the oocyte in humans. Blastocyst is a pre-implantation embryo consisting of a thin-walled hollow sphere of 16-32 cells, which appears in early mammalian development, the wall of which is the trophoblast.Ref: Ganong&;s review of medical physiology; 24th edition; page no:-413