What is typhlosole? Describe its location and function.

(N/A) $\rightarrow$ The typhlosole is a characteristic internal median fold of the dorsal wall of the intestine in earthworms.
$1.$ Location: It is present in the intestine between the $26^{th}$ and $35^{th}$ segments.
$2.$ Function: Its primary function is to increase the effective surface area for the absorption of digested food in the intestine.
$(a)$ Pre-typhlosolar region: The part of the intestine extending up to the origin of the intestinal caeca is called the pre-typhlosolar region.
$(b)$ Post-typhlosolar region: The last part of the intestine (approximately the last $23^{rd}$ to $25^{th}$ segments) lacks typhlosoles and is referred to as the post-typhlosolar region,which leads to the anus.