The human embryonic genome is karyotypically complex, with chromosomally abnormal cells preferentially located away from the developing fetus.

Study Question: Are chromosome abnormalities detected at Day 3 post-fertilization predominantly retained in structures of the blastocyst other than the inner cell mass (ICM), where chromosomally normal cells are preferentially retained?

Summary Answer: In human embryos, aneuploid cells are sequestered away from the ICM, partly to the trophectoderm (TE) but more significantly to the blastocoel fluid within the blastocoel cavity (Bc) and to peripheral cells (PCs) surrounding the blastocyst during Day 3 to Day 5 progression.

What Is Known Already: A commonly held dogma in all diploid eukaryotes is that two gametes, each with 'n' chromosomes (23 in humans), fuse to form a '2n' zygote (46 in humans); a state that remains in perpetuity for all somatic cell divisions. Human embryos, however, display high levels of chromosomal aneuploidy in early stages that reportedly declines from Day 3 (cleavage stage) to Day 5 (blastocyst) post-fertilization.

Update on preimplantation genetic testing for aneuploidy and outcomes of embryos with mosaic results.

Preimplantation genetic testing for aneuploidy (PGT-A) is used as a frequent add-on for in-vitro fertilization (IVF) to improve clinical outcomes. The purpose is to select a euploid embryo following chromosomal testing on embryo biopsies. The current practice includes comprehensive chromosome screening (CCS) technology applied on trophectoderm (TE) biopsies.

Intergenerational gestational surrogacy in a patient with ovarian dysgerminocarcinoma.

A 20-year-old woman was diagnosed with an ovarian dysgerminoma on the right ovary and underwent fertility-preserving right salpingo-oophorectomy and staging. Eight months later she was found to have a left ovarian solid mass. She underwent controlled ovarian hyperstimulation and oocyte cryopreservation before total abdominal hysterectomy, left salpingo-oophorectomy, and exploratory surgery were performed.

Death of a Female Prostitute Due to Intestinal Obstruction by an Unknown Substance.

A young adult black female, known to be a prostitute and suspected of smuggling narcotics, was found dead in her apartment in a state of early decomposition. Oval-shaped gray-white masses of exogenous origin protruded from the anus. The autopsy showed dilatation of the folds of the large intestine, which were almost completely filled with these oval-shaped gray-white masses of foreign material.