Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Accessory Structures of the Skin: Hair and Hair Follicles

Accessory Structures of the Skin: Hair and Hair Follicles

Hair and hair follicles are integral components of the integumentary system. Hair is a filamentous structure composed mainly of a protein called keratin. It is found on the surface of the skin throughout the body, except for areas such as the palms of the hands and soles of the feet.
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Hair strands originate at the epidermal penetration called the hair follicle. The hair shaft is the part...

Accessory Structures of the Skin: Hair Growth and Types

Accessory Structures of the Skin: Hair Growth and Types

Hair growth begins with the production of keratinocytes by the basal cells of the hair bulb. As new cells are deposited at the hair bulb, the hair shaft is pushed through the follicle toward the surface. Keratinization is completed as the cells are pushed to the skin surface to form the shaft of hair that is externally visible. The external hair is completely dead and composed entirely of keratin. Hair can be cut or shaven without damaging the hair structure because the cut is superficial. Most...

Hair Cells

Hair Cells

Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here.

Convergent Evolution

Convergent Evolution

Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.

Folliculogenesis

Folliculogenesis

Folliculogenesis is the development of ovarian follicles, the specialized structures within the ovarian cortex where oogenesis, or egg development, occurs. This process is essential for female reproductive health and begins during fetal development when primordial follicles are formed. Each primordial follicle comprises a primary oocyte in the center, surrounded by a single layer of squamous pre-granulosa cells. These follicles remain dormant in late prophase I of meiosis until triggered by...

The Evidence for Evolution

The Evidence for Evolution

Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

PNA-lectin histochemistry shows putative epidermal cells secreting antifreeze glycoproteins (AFGPs) in the Antarctic fish Trematomus bernacchii (Boulenger, 1902).

Anatomical record (Hoboken, N.J. : 2007)·2026

Same author

Lipid composition of the regenerating epidermis in lizard indicates the formation of an efficient cutaneous barrier against water-loss that favors tail regeneration.

Tissue & cell·2026

Same author

Induction of limb regeneration in lizards in relation to the expression of the signaling proteins FGF8 and Shh.

Anatomical record (Hoboken, N.J. : 2007)·2026

Same author

Review. Cell Biology and Immunohistochemical Evidence of the Transition Between an Aquatic to a Terrestrial-Waterproof Epidermis in the Archosaurian Alligator.

Journal of experimental zoology. Part B, Molecular and developmental evolution·2026

Same author

The developing alligator tongue undergoes a soft form of cornification associated with intermediate filament keratins.

Journal of anatomy·2026

Same author

Histological and Immunohistochemical Analyses on the Formation of the Split Plane in Developing Autotomous Tail Vertebrae of the Lizard Anolis lineatopus.

Journal of morphology·2025

Search research articles

Related Experiment Video

Updated: May 21, 2026

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Published on: February 28, 2013

Perspectives on hair evolution based on some comparative studies on vertebrate cornification.

Lorenzo Alibardi¹

¹Comparative Histolab and Dipartimento di Biologia, University of Bologna, Bologna, Italy. lorenzo.alibardi@unibo.it

Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution

|June 20, 2012

Summary

Mammalian hair likely evolved from glands, not scales. This hypothesis suggests an onion-like structure developed from glandular cells, with specific gene activation and depression driving hair formation.

More Related Videos

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

Published on: June 25, 2014

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

Published on: June 16, 2022

Related Experiment Videos

Last Updated: May 21, 2026

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Published on: February 28, 2013

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

Published on: June 25, 2014

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

Published on: June 16, 2022

Area of Science:

Evolutionary biology
Developmental biology
Mammalian biology

Background:

Mammalian hair is crucial for survival and thermoregulation.
The evolutionary origin of hair, whether from scales or glands, remains debated.
Previous studies hint at shared signaling pathways between hair and gland development.

Purpose of the Study:

To propose a hypothetical model for hair evolution from glandular structures.
To investigate the potential morphogenetic processes involved in transforming glands into hair follicles.
To explore the role of signaling molecules and gene regulation in this evolutionary transition.

Main Methods:

Comparative analysis of hair and gland morphogenesis.
Immunocytochemical studies to examine protein distribution.
Hypothetical reconstruction based on evolutionary and developmental principles.

Main Results:

Hair's onion-like structure may originate from glandular pegs.
Specific keratins and proteins (involucrin, trichohyalin) form the hair medulla and inner root sheath.
Activation of beta-catenin signaling and keratogenic genes, alongside depression of lipidogenic genes, is proposed.
Evolution of new genes in synapsids led to cortex and cuticle formation.
Medulla obliteration and cuticle formation are hypothesized later stages.

Conclusions:

Hair evolution from glands is a plausible hypothesis supported by developmental and genetic evidence.
The transition involved significant modifications in gene expression and cellular organization.
This model provides a framework for understanding the evolutionary development of mammalian hair.