'internal regions' is a correct and usable phrase in written English.
You could use it to refer to a specific area or spaces inside a larger entity. For example, "There are many internal regions of the human brain that scientists have yet to explore."
AMT1-specific primers were designed and used to amplify the AMT1 internal regions.
She clicked her mouse, causing a virtual scalpel to lay the pig's kidney open, its internal regions highlighted by blinking labels.
Many periodic solutions have internal regions of rapid change internal boundary layers.
But such risk pooling is more common between internal regions of countries than it is between countries.
Almost all intrinsic proteins contain special amino acid sequences, generally about 20- to 24-amino acids long, that extend through the internal regions of the cell membrane.
Magnetic field design is discussed and we show that it is impossible to specifically target internal regions using an externally applied field.
The quantum helium atoms in the 0.7-nm CNTs system entered the internal regions of the nanopores more quickly than the classical helium atoms regardless of the type of nanopores.
Second and third column shows different internal regions of the cell seeded coral-loaded rolls.
Several internal regions with disorder scores between 0.2 and 0.5 are expected to have high conformational flexibility.
High levels of diversity were observed in four regions the 5′ and 3′ LTR ends, plus two internal regions as shown in Fig. 5.
The smectite family has spectral hydration characteristics that have been attributed to adsorption of water on the external surfaces of the clay as well as internal regions.
