Merkel-like cell distribution in the epithelium of the human vagina. An immunohistochemical and TEM study

Abstract

Human Merkel cells (MCs) were first described by Friedrich S. Merkel in 1875 and named “Tastzellen” (touch cells). Merkel cells are primarily localized in the basal layer of the epidermis and concentrated in touch-sensitive areas. In our previous work, we reported on the distribution of MCs in the human esophagus, so therefore we chose other parts of the human body to study them. We selected the human vagina, because it has a similar epithelium as the esophagus and plays very important roles in reproduction and sexual pleasure. Due to the fact that there are very few research studies focusing on the innervation of this region, we decided to investigate the occurrence of MCs in the anterior wall of the vagina. The aim of our research was to identify MCs in the stratified squamous non-keratinized epithelium of the human vagina in 20 patients. For the identification of Merkel cells by light microscopy, we used antibodies against simple-epithelial cytokeratins (especially anti-cytokeratin 20). We also tried to identify them using transmission electron microscopy. Our investigation confirmed that 10 (50 %) of 20 patients had increased number of predominantly intraepithelial CK20 positive “Merkel-like” cells (MLCs) in the human vaginal epithelium. Subepithelial CK20 positive MLCs were observed in only one patient (5%). We tried to identify them also using transmission electron microscopy. Our investigation detected some unique cells that may be MCs. The purpose of vaginal innervation is still unclear. There are no data available concerning the distribution of MCs in the human vagina, so it would be interesting to study the role of MCs in the vaginal epithelium, in the context of innervation and epithelial biology.

Merkel Cells Are Multimodal Sensory Cells: A Review of Study Methods

“…CK20 is the most specific marker known for both human and rodent epidermal samples and co-localizes with CK8 in 99% of mouse MCs [ 32 , 42 ]. Consequently, anti-CK20 antibodies offer the highest degree of specificity for MCs, ensuring their straightforward identification whether by light or transmission electron microscopy [ 14 , 42 , 43 ].…”

Histochemistry as a versatile research toolkit in biological research, not only an applied discipline in pathology

“…[37][38][39][40][41][42] The biology of stem cells was extensively investigated through the labelling by specific molecular markers, during development and in the adult. [43][44][45][46] The molecular organization of cells and tissues was carefully analyzed [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] especially in poorly described species of mammals [55][56][57] and non-mammalian vertebrates [58][59][60][61] or in invertebrates, 62,63 while immunohistochemistry was crucial to elucidate the topographic distribution of cell lineages in different organs, [64][65][66] especially in the nervous system, [67][68][69][70][71] and during embryogenesis and the pre-or postnatal development, [72][73]…”

Ultrastructural histochemistry in biomedical research: Alive and kicking

“…The ultrastructural morphological approach at TEM has been widely used in basic and applied biomedical research for the study of different tissues under unperturbed or experimental conditions: tooth structure and repair; 47 , 48 white adipose tissue classification; 49 , 50 stem cells culture for reconstructive purpose; 51 , 52 skeletal muscle features under experimental 53 , 54 and pathological 55 , 56 conditions; liver response to pretransplantation treatment; 57 female reproductive organs 58 and explanted oocytes for in vitro reproduction; 59 , 60 post-implant skin modification; 61 autopsy myocardium for diagnostic purposes 62 .…”