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A Contemporary View on Felix Pinkus' Concept of the Vitreous Membrane
Karola Stieler1, Annika Vogt1, Wolfram Sterry1
1Department of Dermatology and Allergology, Clinical Research Center for Hair and Skin Science, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and -Berlin Institute of Health, Berlin, Germany.
Introduction:
Felix Pinkus' concept of the vitreous membrane (VM) published in 1927 describes circular folds protruding into the outer root sheath (ORS), which, in his opinion, serve as interdigitations between the outer root sheath (ORS) and the VM. This concept currently seems to have fallen into oblivion.
Objective:
To determine the origin and possible function of the VM in the proliferation and vascularization of the hair follicle (HF).
Methods:
Serial investigation of healthy skin probes with histological (hematoxylin & eosin and periodic acid-Schiff) and immunohistochemical examination (Ki67, CD56, CD8, and collagen IV) were performed.
Results:
Morphological variations of the VM in various HFs such as protrusions and folds, the latter unilateral, bilateral or circular, some acute-angled, were found. Similarly, protrusions of the VM into the ORS were observed, that consisted of capillary tissue together with perifollicular tissue and VM mimicking minimal variants of the dermal papilla.
Conclusions:
Pinkus' concept of the VM is revisited, reproduced and possible functions are proposed. Since these structures are found in a HF region with a high metabolic dynamism, they may be involved in differentiation or nutrition, or else be formed as a result of pressure arising from outgrowing hair shafts.
Insights
Felix Pinkus's vitreous membrane (VM) concept is revisited, revealing its potential role in hair follicle (HF) proliferation and vascularization. These structures may aid in HF differentiation, nutrition, or result from hair shaft pressure.
Area of Science:
- Dermatology
- Histology
- Hair Biology
Background:
- Felix Pinkus described the vitreous membrane (VM) in 1927 as circular folds within the outer root sheath (ORS).
- This concept of the VM's function in hair follicle (HF) structure has been largely overlooked.
- The VM's role in HF proliferation and vascularization requires further investigation.
Purpose of the Study:
- To determine the origin and potential functions of the vitreous membrane (VM).
- To investigate the VM's involvement in hair follicle (HF) proliferation and vascularization.
Main Methods:
- Histological examination using hematoxylin & eosin and periodic acid-Schiff staining.
- Immunohistochemical analysis with markers Ki67, CD56, CD8, and collagen IV.
- Serial investigation of healthy human skin samples.
Main Results:
- Observed morphological variations of the VM, including folds and protrusions into the outer root sheath (ORS).
- Identified VM protrusions containing capillary and perifollicular tissue, resembling dermal papilla variants.
- Documented diverse VM structures across different hair follicles.
Conclusions:
- Revisiting and reproducing Felix Pinkus's concept of the vitreous membrane (VM).
- Proposed functions for the VM include roles in hair follicle (HF) differentiation or nutrition.
- The VM may also be an artifact of pressure from the growing hair shaft.
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