Longitudinal vs Transverse Section
When the anatomical structures of animals and plants are studied, the longitudinal and transverse sections become extremely important. This importance is mainly due to the unveiling of the hidden tissues and organs through a longitudinal or transverse section. Usually, a live animal cannot be dissected longitudinally or transversely, yet the dead bodies could be studied with these kinds of sections that will be helpful to understand the living being of the same species.
Longitudinal Section
When a vertical section is cut along the longest axis of an animal or a plant, the longitudinal cut is made. However, it is sometimes defined as the longest section cut in the vertical plane of an animal or a plant. There may be more than one longitudinal section, and the main difference between those sections will be the distance from the lateral ends to the sectioning plane. When the longitudinal section is made through the line of symmetry, the resulted section is called as a sagittal section.
In anatomy, the longitudinal cut serves in many ways to understand the structures and their functions. The digestive and nervous systems of elongated animals (worms or snakes) can be easily understood only through a longitudinal section. The revealing of internal anatomical structures through longitudinal sections enables to make strong suggestions about the evolutionary history of modern species when those are compared with the fossil evidences. The longitudinal section is not limited to the entire body, but it could be used to refer the same dissection as described above for an organ, as well. However, such section of an organ would reveal the cellular and/or tissue level organization. The longitudinal section of a skeletal muscle will show the muscle fibres with their important regions, which makes it very easy to understand the mechanism of muscle contraction and relaxation.
Transverse Section
Transverse section is a cut made in a plane that is made across the body of an animal, a plant, an organ, or a tissue. It is usually referred as the cut made between left and right. The transverse section usually runs between the lateral ends of an organism, from left to right or the other way around. A transverse section is right-angled with the longitudinal section. This section can be made through different levels or heights of an organ or a structure. Therefore, many transverse sections can be made to observe the anatomy of an organ. As an example, the scan results of a brain show the anatomical structure in different transverse sections, which is useful in locating any problem in the brain. When ultrasound wave scans are performed, the anatomical organization is studied at different levels, which means the anatomy of the scanned organ(s) could be studied through different transverse sections.
Usually, a transverse section would not reveal all the structures in an animal or a plant since organs are different tissues formed at different levels inside the organism. Therefore, few sections have to be made to understand the entire anatomy of an organism. The alimentary track of the animals is usually long in all the animals, and transverse sections at different levels of the track will reveal the anatomy and functions such as toothed mouths, oesophagus with mucus layers, secretory stomach, absorbing guts, etc.
What is the difference between Longitudinal and Transverse Section?
• Longitudinal section runs through the anterior posterior axis, whereas the transverse section goes between lateral ends.
• Longitudinal sections are usually longer than transverse sections.
• Usually, the number of possible transverse sections is higher than the number of possible longitudinal sections to be made through an organ or organism.
• Longitudinal section is right-angled to the transverse section.