# morulas/compacted/cavitating, blasts, HB, XB what are they???



## greatgazza

Hi there

I just wondered if someone could give me the low down on what some of these actually are?  I know a blast (blastocyte) seems like a good thing once an egg has been fertilised and then goes on to blast stage (and i know it costs more to get to this stage as it's a good thing etc)...what i don't understand is what is a good embie, what is a good blast?  What does HB or XB mean?

I read about grade 1, 10 cell, grade 2, 8 cell etc but don't really know what it means.  I get that grade 1 means good but what are the different options and what is poor, average and good.... in embie/blast terms.  Also what is a morula?  And then a compacted/compacting or cavitating one? I googled it but didn't really understand it. 

This is all new to me as I've not had IVF yet which is my next move so i want to have a vague idea of what the docs might be telling me and if there are any decisions i need to make to be better informed and know what they're talking about rather than just taking everything they say without question.


Thanks GG X


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## greatgazza

also, sorry, what is a tandem cycle?  is that when you go to use your own eggs but if that doesn't work there are donor eggs on standby as back up?

GGx


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## Mistletoe (Holly)

Embryos are variable things to an extent, but below is the ideal for a ''normal'' embryo that went to school and read the textbook  - but don't forget cells don't have a clock or work schedule and things can take a few hours more or less. Sometimes the point at which they look under the microscope one cell might have divided, but not the one next to it so you might have 5 cells or 7 cells. If the cell division cycle is a couple of hours later in a particular embryo, by the time you get to day 5 you might have an early blastocyst or one that is still compacting, getting to blast on day 6. All can make a baby. Ones that are far too fast or far too slow probably have inaccurate genetic division and will not be used in treatment.

Normally an embryo starts as an egg on day 0.
Day 1 it should be fertilised - shown by having 2 pronuclei visible.
Day 2 it should be 2-4 cells.
Day 3 it should be 8 cells
Day 4 it should be 16-32 cells and the edges of the cells become less defined - it is compacting and termed a morula.
Day 5 it should be over 100 cells and have an outer cell mass that becomes the placenta and an inner cell mass that becomes the baby with a nice cavity in the middle and becoming fully expanded - termed a blastocyst.
Day 6 it should be starting to hatch out of its shell
Day 7 it should implant into the wall of the uterus

Grading on day 3 - morphology under the microscope can give an idea of quality, but it is not an absolute. Cells should divide with even sizes and there should be little in the way of fragments in the embryo. There ideally should be clearly defined cells with out any little fragments. Grades are usually 1-4 with 1 being the best - but some clinics rate 4 the best, so check what your clinic say.
Grade 1 the cells are even sized with no fragments, down to grade 4 with uneven cells and lots of fragments.

Fragmented embryos might do less well, but grade 3, if this is all you have available can, and have made babies in the past. The look of an embryo under the microscope gives an idea, but it does not prove chromosomes are normal - there are more complicated tests that could be done for that, but really only done if you have repeated failures or a genetic disorder you want to exclude as it is expensive and relatively new.
Fragmented embryos do not survive freeze thaw - so only grade 1-2 embryos will be frozen.

Blastocysts can only be graded once the cavity has formed - ideally there should be a good quantity of cells in the outer and inner cell mass and they should look even with a nice hollow centre taking up more most of the embryo.

HB - I guess is a hatching blast and XB - I guess is an expanded blast.

There is some embryology on the front page of fertility friends.

The best pictures and explanation of embryology and grading is on the Chicago site. Have a read and a click around this site and you will learn all you need to. This site uses grade 4 as best - so again be sure to know which scale your clinic are using - 1 best or 4 best.

http://www.advancedfertility.com/embryoquality.htm

/links


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## greatgazza

That's fantastic HH thank you so much for all that, i'll have a look around where you have said.

GG x


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## ♥JJ1♥

Gg Hazel has given you a comprehensive reply but also some clinics don't grade 1,2,3 they have A,B etc so ask at you clinic how they grade.
A tandem cycle is indeed just that if you look at dogus clinic in Cyprus they do it- it was something I asked for in the uk but they denied it as too difficult- not cheap as two of you are having ivf cycles.


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