胚胎分裂速度

胚胎分裂速度
4-cells: 44h
8-cells: 68h
morula: 92h
囊胚: 116h

morula: 進入第4次有絲分裂(16>32cell) & compaction

http://humrep.oxfordjournals.org/content/26/6/1270.full

Table IV

Timing of observation of fertilized oocytes and embryos, and expected stage of development at each time point.

Type of observation	Timing (hours post-insemination)	Expected stage of development
Fertilization check	17 ± 1	Pronuclear stage
Syngamy check	23 ± 1	Expect 50% to be in syngamy (up to 20% may be at the 2-cell stage)
Early cleavage check	26 ± 1 h post-ICSI	2-cell stage
	28 ± 1 h post-IVF
Day-2 embryo assessment	44 ± 1	4-cell stage
Day-3 embryo assessment	68 ± 1	8-cell stage
Day-4 embryo assessment	92 ± 2	Morula
Day-5 embryo assessment	116 ± 2	Blastocyst

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  Table VII
  

  Consensus scoring system for Day-4 embryos.

  Grade	Rating	Description
  1	Good	• Entered into a fourth round of cleavage.
  		• Evidence of compaction that involves virtually all the embryo volume.
  2	Fair	• Entered into a fourth round of cleavage.
  		• Compaction involves the majority of the volume of the embryo
  3	Poor	• Disproportionate compaction involving less than half of the embryo, with two or three cells remaining as discrete blastomeres Table VIII Consensus scoring system for blastocysts. Grade Rating Description Stage of development 1 Early 2 Blastocyst 3 Expanded 4 Hatched/hatching ICM 1 Good Prominent, easily discernible, with many cells that are compacted and tightly adhered together 2 Fair Easily discernible, with many cells that are loosely grouped together 3 Poor Difficult to discern, with few cells TE 1 Good Many cells forming a cohesive epithelium 2 Fair Few cells forming a loose epithelium 3 Poor Very few cells The scoring system for blastocysts is a combination of the stage of development, and of the grade of the ICM and of the TE (e.g. an expanded blastocyst with a good ICM and a fair TE would be scored as 312). It is a numerical interpretation of the Gardner scale (Gardner and Schoolcraft, 1999a,b).