this is because the alimentary canal consists of parts which the food flow into the bolus hence it needs to be sliding into the alimentary canal until it come to be digested.
Repeling dust and micro organisms and secreating mucos.
Ependymal cells line the central canal of the spinal cord
Enterochromafin cells in the alimentary canal
Ependyma
osteocytes
Ependymal cells
Bone cells surround Haversian canals. Osteon (Haversian system) is the structural unity of bone. Spaces for osteocytes are called lacunae. The matrix is present in concentric rings called lamellae. Canaliculi are canals that join lacunae with the central Haversian canal (central canal)
fiber
In the center of the diaphysis of long bones like the humerus and femur, there is a canal called the medullary or marrow cavity. This canal contains bone marrow which produces blood cells.
it is a canal system found in sponges(porifera phylum). its example is Leucon. the intresting fact is that this is the only water canal system present in sponges which do not have SPONGOCOEL. in this water moves inside through ostiathen to incurrent canal then prosodi then flagellate cells and then to apodi then to excurrent canal and den to osculum then out..!!
An osteon is composed of concentric rings of bone matrix called lamellae surrounding a central canal called the Haversian canal. Within the Haversian canal run blood vessels and nerves that supply nutrients to bone cells. Osteocytes, the bone cells, are located in spaces called lacunae between the lamellae.
it is a canal system found in sponges(porifera phylum). its example is Leucon. the intresting fact is that this is the only water canal system present in sponges which do not have SPONGOCOEL. in this water moves inside through ostiathen to incurrent canal then prosodi then flagellate cells and then to apodi then to excurrent canal and den to osculum then out..!!