The main difference between vellus and terminal hair is that the vellus hair is the type of hair which develops in the body during childhood, whereas the terminal hair is the type of hair which develop in the body after puberty. Furthermore, the vellus hair is thin, short, slightly-colored, and barely noticeable while the terminal hair is thick, long and dark. In addition, adult females retain vellus hair mostly even after puberty while a,dult females develop terminal hair in many areas includi,ng the face, chest, abdomen, arms, legs, and foot.
In brief, the vellus and terminal hair are two types of hair which develop in the human body after birth. Generally, androgens are hormones responsible for the development of terminal hair from vellus hair.
Key Areas Covered
1. What is Vellus Hair
– Definition, Structure, Occurrence
2. What is Terminal Hair
– Definition, Structure, Occurrence
3. What are the Similarities Between Vellus and Terminal Hair
– Outline of Common Features
4. What is the Difference Between Vellus and Terminal Hair
– Comparison of Key Differences
Key Terms
Androgens, Hair Follicle, Hair Shaft, Melanin, Terminal Hair, Vellus Hair
What is Vellus Hair
Vellus hair is the short, thin, and light-colored hair that occurs during childhood. It can grow up to 2 mm in length. Moreover, it grows in most of the body parts except lips, palm, back of the ear, sole of the foot, etc. The main function of vellus hair is to keep the body warm.
Figure 1: Vellus Hair
Furthermore, vellus hair mostly occurs in the body of adult females, even after their puberty. Vellus hair is different from lanugo hair, which is the type of hair in the fetus. Males have a much longer and more prominent type of vellus hair, which is often called ‘peach fuzz’ or ‘pube bread’. Although this type of hair is extremely thin and light-colored, it can grow up to 4 cm.
What is Terminal Hair
Terminal hair is the type of long, thick, and dark color hair, which occurs with puberty in both males and females. Generally, vellus hair develops into terminal hair in response to androgens, which is a class of hormones that occur in higher amounts in males. Thus, males develop terminal hair in many areas of the body including the face, chest, abdomen, arms, legs, and foot as one of the secondary sex characteristics.
Figure 2: Development of Terminal Hair
Moreover, some significant characteristics of terminal hair include the positioning of the hair follicle deeply in the dermis, the presence of a cortex and medulla in the hair shaft, and the presence of higher amounts of melanin in the cortex. Here, the bulk of the hair shaft becomes the cortex, containing longitudinally oriented cells. On the other hand, the vertical column of horizontal cells represents the medulla with large air spaces. Meanwhile, eumelanin and pheomelanin are the two types of melanin which occurs in the cortex. Generally, eumelanin is responsible for the black and brown color while pheomelanin is responsible for the red and blond color.
Similarities Between Vellus and Terminal Hair
- Vellus and terminal hair are two types of hair which grow in the human body.
- Both appear after birth.
- They occur in various body areas except for the lips, the back of the ear, the palm of the hand, the sole of the foot, some external genital areas, the navel, and scar tissue.
- The hair shaft of both types of hair is made up of keratin. The hair follicle is the living portion which gives rise to the hair shaft.
- In addition, the outermost layer of the hair shaft is the cuticle, which is translucent, allowing light to pass to the inner layer.
- Furthermore, hair follicle occurs in the dermis of the skin while being connected to a sebaceous gland and a bulge containing stem cells.
- Melanocytes occur in the bulb of both types of hair.
Difference Between Vellus and Terminal Hair
Definition
Vellus hair refers to the short, fine hair, which covers the most part of the human body while terminal hair refers to the thick, strong, and pigmented hair, which are fully matured.
Structure
Vellus hair is thin, short, slightly-colored, and barely noticeable while terminal hair is thick, long, and dark.
The occurrence of the Hair Follicle
The hair follicle of vellus hair occurs less deeply while the hair follicle of terminal hair occurs deeply.
Structure of the Hair Shaft
The shaft of vellus hair does not contain a medulla while the shaft of the terminal hair contains a medulla.
Length
Vellus hair can be up to 2 mm long while terminal hair can be up to 3 feet long.
Development
Moreover, vellus hair is the type of hair which develops in the body during childhood while terminal hair is the type of hair which develop in the body after puberty.
Occurrence
Vellus hair occurs before puberty during childhood in both males and females while terminal hair develops in the body after puberty in both males and females.
Significance of the Occurrence
Adult females retain vellus hair mostly even after puberty while adult females develop terminal hair in many areas including the face, c,hest, abdomen, arms, legs, and foot.
Effect of Androgens
Androgens have no effect on the development of vellus hair while androgens are responsible for the development of terminal hair from vellus hair.
Importance
Furthermore, vellus hair permits thermal regulation of the body while terminal hair is one of the secondary sex characteristics in both males and females.
Removal
While vellus hair can be removed by a hot wax without using a strip, terminal hair can be removed by a warm wax with the use of a strip.
Conclusion
Vellus hair is the type of hair that occurs in the body after birth. Generally, this type of hair is thin, short, and light-colored. It is also responsible for the thermal regulation of the body. Terminal hair, on the other hand, is the type of hair that occurs in the body after puberty. Significantly, androgens are responsible for the transformation of vellus hair into terminal hair, which is thick, long, and dark-colored. Basically, terminal hair is one of the secondary sex characteristics of both males and females. Therefore, the main difference between vellus and terminal hair is their structure and importance.
References:
1. Huang, Xiyong, et al. “Review of Human Hair Optical Properties in Possible Relation to Melanoma Development.” Journal of Biomedical Optics, vol. 23, no. 05, Nov. 2018, p. 1., doi:10.1117/1.jbo.23.5.050901.
Image Courtesy:
1. “Huid” By Svdmolen – Self-published work by Svdmolen (CC BY 2.5) via Commons Wikimedia
2. “VellushaarTerminalhaar-translation” By Kubek15/Slave – File:Androgensensibilitaet.JPG (CC BY-SA 4.0) via Commons Wikimedia
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