Is it only teguments strong? In this case you may disrupts it mechanicaly including using a hammer. If it has stronger inner parts, you may try germinate it. When embibed it become more softer. Good luck. Yours Prof. Alfredo Gui Ferreira.

you  need to bring the seeds close to germination and then slice desired part 

You probably can try 'soaking' them in the water first. I needed to cut open the cotton seeds (see attached) for my experiment. The seeds are very hard to cut open when they are dry. I soaked them in water for several hours (not germinated). After that, most of them could be cut open easily (although still a few of them were hard to be cut open). You can try and find out. Let us know the results if you do so.

thank for your answer. It is easy when i soaked and germinated. Excuse me i want to do extraction in the laminar flow to do TISSUE CULTURE OF THESE EMBRYOS when i sterilized..

the embryos are so fragile to sterilize.if it is possible to extract directly when i sterilize in the  laminar flow hood but the teguments are very strong. i will try to extract them and sterilize if is not possible

In this case, you only like to have the embryos in order to cultivate them in vitro. So, if used disrupt the tegmument, you can reach the inner part catching the embryo. Do the procudure  in side of laminar flow hood. Yours

Alfredo Gui Ferreira- retired Professor at UFRGS/Brazil.

Thank you Pr Alfredo

Firstly, make the scarification of seeds. Then put them to soak in distilled water. After imbibed, the integument becomes more softer and the embryo can be easily separated.

thank you for the contribution

Dear Dr./Dra. Tchouga Alvine.

I suggest you to verify the possibility of buying a burr drill to perforate the ebony seeds using a slow speed hand piece. You can verify in a dentist shop because this equipment is very cheap. Long time ago,  I had one  for working with impermeable seed coats. You can perforate the opposite side of the seed embryo using a tiny burr, and water will do the next. I do not know if the equipment I had is still available in the market but it is the best way to work in the sterilized conditions that you need.  Best regards. Walter

thank you Professor