You can concentrate the sample using precipitation/resolving (in a smaller volume). Another possibility is vaccuum-concentration (you need a vaccuum centrifuge).

Dear Lili Hou, how are you doing today?

The trizol should work fine for 50 to 100mg of tissue. However, depending on the tissue you will get more RNA from a tissue that express a lot of RNA comparing with one that do not express at all. For example, a liver sample will yield more RNA than a muscle sample, because liver express more RNA. I think ovary is not so difficult to yield enough quantity of RNA. Ovary contains oocytes, theca cells, granulosa cells, among other cells that have significant expression of RNA. Nevertheless, you should be careful with the extraction and make sure that you are following the manufacturer’s instructions correctly. Ovary contains little quantities of lipid-peptides such as vitellogenin, that can cause some problems during the extraction. Just make you are using enough trizol to lysis the entire tissue and wash carefully.

Also, try to eluate the RNA in a volume that will help you to work after. I usually eluate with 20 to 30 ul of RNA-Free water, and then dilute the to get around 300ng/ul. This start volume depends on the size of RNA pellet. If your pellet is very smalls, try to eluate in 10 or 20ul of RNA-free water, measure the RNA concentration, and then dilute in the appropriate work volume if necessary. Well, best regards and good luck with your research.

https://www.nature.com/articles/s41598-017-04327-y

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