It’s the first one!
compact bone is a dense bone with a bony matrix that is solidly filled with arya if ground substance and inorganic salts, leaving only tiny spaces (lacunae) that contain osteocytes, or bone cells. Immature compact bone DOES NOT CONTAIN OSTEONS and has a woven structure.
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Every species exhibits variations based on various genes being activated at various times. An example with humans can be eye color or hair color. What species means is that all members of a species can procreate with healthy, capable of procreating progeny, but anything else is just a variation.
The surface area of a sphere can be approximated as follows: Surface area = 4πr2; where r is the radius of the sphere; π is a constant that is roughly equal to 3.
The half-life of a radioisotope is the amon the symbol 42He, the subscript 2 is the mass number for helium and the superscript 4 is the atomic number for helium.