The concentric rings of calcified intercellular substance arranged around Haversian canals are called Lamellae
Explanation:
The microscopic tubes situating at the outer region of cortical bone which gives way to the nerves and blood vessels to travel through it is referred to as Haversian canals. The channels of the canals are composed of concentric substance called Lamellae.
It surrounds the nerve cells and vessels of bones and makes a communication with cells of the bone through canaliculi. Lamellaes compose concentric rings made up of calcified intercellular substance around the tissue of bones.
The answer is A. - Prokatyotic cells lack a defined nucleus while eukaryotic cells do have one :) I loved learning about the cells in biology! But I noticed your question is worded a little differently so the nucleus would be the one thing a eukaryotic cell has that a prokatyotic cell does not...
The phenomenon is called an equinox. More specifically when it is September it is called the autumnal equinox ,and when it is March it is called the vernal equinox. Hope this helped!
