Question

Haversian system is typically found in the bones of
A. Fishes
B. Aves
C. Reptiles
D. Mammals

Answer 1

Hint: The haversian system is a tubular network seen around narrow channels of the outer region of bone and they are formed of structures known as lamellae.

Complete Answer:
Let's have an analysis on the options to find the correct answer.

Option A: The haversian system is not seen in fishes. Skeletal systems of fishes are mainly made of either bones or cartilage. Fishes exhibit a simple skeletal system when compared to other organisms. Therefore, this is the incorrect option.

Option B: Haversian system is absent in avian bones. A type of bone called pneumatic bone constitutes the skull, humerus, pelvic girdle of birds. A significant type of bone found in aves are medullary bones. Therefore, this is the incorrect option.

Option C: The haversian system is absent in reptiles. Reptiles to some extent, share some of the basic skeletal structures of mammals. Specific modifications are displayed in the skeletal systems of snakes, tortoises and crocodiles. Therefore, this is the incorrect option.

Option D: The haversian system is present in mammals. It is one of the diagnostic features of mammalian bones. These are microscopic tubes situated in the outermost region of bones. This region is known as compact bone or cortical bone. Blood vessels and nerves travel through this region. The channels of the haversian system are made of layers known as lamellae. Throughout the bones, haversian canals surround both blood vessels and nerves and helps in the communication with the bone cells. Therefore, this is the correct option.

Thus, the correct option is D) Mammals.

Note: The fundamental functional unit of compact bones is the haversian system or osteon. Osteons are a type of cylindrical structures which have diameters ranging from 0.25 mm to 0.35 mm, that surrounds the haversian canals.