Gardner and Schoolcraft developed criteria for describing blastocysts. This can help select suitable blastocysts for in vitro fertilization. Better blastocysts have a better implantation success rate.
(1) blastocyst grade
(2) inner cell mass (ICM)
blastocele < half of embryo volume
blastocele >= half of embryo volume but does not fill it
blastocele completely fills the embryo
expanded, with blastocele larger than the early embryo
hatching, with herniation of trophectoderm
hatched, completely outside zone
If the grade is 3 to 6, then the inner cell mass and trophoectoderm are graded.
Inner Cell Mass
many cells, tightly packed
several cells, loosely grouped
very few cells
many cells, with tight knit epithelium
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Specialty: Obstetrics & Gynecology