Differential distribution and genetic determination of eccrine sweat glands and hair follicles in the volar skin of C57BL/6 mice and SD rats.

BACKGROUND: Eccrine sweat glands (ESGs) and hair follicles (HFs) are the prominent skin appendages regulating human body temperature. C57BL/6 mice and Sprague-Dawley (SD) rats are the most commonly used model animals for studying ESGs and HFs. Previous studies have shown the distribution of ESGs and HFs in volar hindfeet of C57BL/6 mice, but there are few or no reports on the distribution of ESGs and HFs in volar forefeet of C57BL/6 mice and volar feet of SD rats. Here, we investigated the differential distribution and genetic determination of ESGs and HFs in the volar skin of C57BL/6 mice and SD rats through gross observation, iodine-starch sweat test, double staining with Nile Blue A and Oil Red O, hematoxylin and eosin (HE) staining, double immunofluorescence staining of LIM Homeobox 2 (LHX2)/Na+-K+-ATPase α1(NKA) or LHX2/Na+-K+-2Cl－ cotransporter 1 (NKCC1), and qRT-PCR detection of ESG-related gene Engrailed 1 (En1) and HF-related gene LHX2. RESULTS: The results showed ESGs but no HFs in the footpads of C57BL/6 mice and SD rats, both ESGs and HFs in the inter-footpads (IFPs) of C57BL/6 mice, and neither ESGs nor HFs in the IFPs of SD rats. The relative quantitative change in En1 was consistent with the differential distribution of ESGs, and the relative quantitative change of LHX2 was consistent with the differential distribution of HFs. CONCLUSION: C57BL/6 mice and SD rats had their own characteristics in the distribution of ESGs and HFs in the volar skin, and researchers should choose mice or rats, and even forefeet or hindfeet as their research object according to different purposes. The study provides a basis for selection of optimal animal models to study development, wound healing and regeneration of skin appendages.

Effects of sex and menstrual cycle on sweating during isometric handgrip exercise and postexercise forearm occlusion.

NEW FINDINGS: What is the central question of this study? Do sex and menstrual cycle modulate sweating during isometric handgrip exercise and muscle metaboreceptor stimulation? What is the main finding and its importance? Sex modulates sweating during isometric handgrip exercise, as indicated by the lower sweat output per gland in women than in men, but not during muscle metaboreceptor stimulation. Sweat output per gland during isometric handgrip exercise and muscle metaboreceptor stimulation were lower in the mid-luteal phase than in the early follicular phase in women. Cholinergic sweat gland sensitivity might explain, in part, the individual variation of the response. Our results provide new insights regarding sex- and menstrual cycle-related modulation of the sweating response. ABSTRACT: We investigated whether sex and menstrual cycle could modulate sweating during isometric handgrip (IH) exercise and muscle metaboreceptor stimulation. Twelve young, healthy women in the early follicular (EF) and mid-luteal (ML) phases and 14 men underwent two experimental sessions consisting of a 1.5 min IH exercise at 25 and 50% of maximal voluntary contraction (MVC) in a hot environment (35°C, relative humidity 50%) followed by 2 min forearm occlusion to stimulate muscle metaboreceptors. Sweat rates, the number of activated sweat glands and the sweat output per gland (SGO) on the forearm and chest were assessed. Pilocarpine-induced sweating was also assessed via transdermal iontophoresis to compare the responses with those of IH exercise and muscle metaboreceptor stimulation, based on correlation analysis. Sweat rates on the forearm and chest during IH exercise and muscle metaboreceptor stimulation did not differ between men and women in either menstrual cycle phase (all P ≥ 0.144). However, women in both phases showed lower SGO on the forearm and/or chest compared with men during IH exercise at 50% of MVC, with no differences in muscle metaboreceptor stimulation. Women in the ML phase had a lower forearm sweat rate during IH exercise at 50% of MVC (P = 0.015) and SGO during exercise and muscle metaboreceptor stimulation (main effect, both P ≤ 0.003) compared with those in the EF phase. Overall, sweat rate and SGO during IH exercise and muscle metaboreceptor stimulation were correlated with pilocarpine-induced responses (all P ≤ 0.064, r ≥ 0.303). We showed that sex and menstrual cycle modulate sudomotor activity during IH exercise and/or muscle metaboreceptor stimulation. Cholinergic sweat gland sensitivity might explain, in part, the individual variation of the response.

Miliaria crystallina induced by idarubicin and all-trans-retinoic acid: Two case reports.

Miliaria crystallina is a benign, self-limiting disorder of the eccrine sweat glands characterized by the obstruction of the sweat ducts, which leads to secondary sweat retention into stratum corneum. We present two patients with MC during treatment with idarubicin and all-trans-retinoic acid (ATRA) for acute promyelocytic leukaemia (APL). Anthracyclines can be excreted through sweat and induce MC through exfoliation. The use of idarubicin in combination with ATRA would favour the process of producing a peeling effect. Reports of MC associated with idarubicin and ATRA are scarce. Recognizing this benign entity and its triggers will help to differentiate it from other skin reactions, improving the management of patients by avoiding unnecessary studies and treatments.

The relative contribution of α- and ß-adrenergic sweating during heat exposure and the influence of sex and training status.

While human eccrine sweat glands respond to adrenergic agonists, there remains a paucity of information on the factors modulating this response. Thus, we assessed the relative contribution of α- and ß-adrenergic sweating during a heat exposure and as a function of individual factors of sex and training status. α- and ß-adrenergic sweating was assessed in forty-eight healthy young men (n = 35) and women (n = 13) including endurance-trained (n = 12) and untrained men (n = 12) under non-heat exposure (temperate, 25°C; n = 17) and heat exposure (hot, 35°C; n = 48) conditions using transdermal iontophoresis of phenylephrine (α-adrenergic agonist) and salbutamol (ß-adrenergic agonist) on the ventral forearm, respectively. Adrenergic sweating was also measured after iontophoretic administration of atropine (muscarinic receptor antagonist) or saline (control) to evaluate how changes in muscarinic receptor activity modulate the adrenergic response to a heat exposure (n = 12). α- and ß-adrenergic sweating was augmented in hot compared with temperate conditions (both P ≤ .014), albeit the relative increase was greater in ß (~5.4-fold)- as compared to α (~1.5-fold)-adrenergic-mediated sweating response. However, both α- and ß-adrenergic sweating was abolished by atropinization (P = .001). Endurance-trained men showed an augmentation in α- (P = .043) but not ß (P = .960)-adrenergic sweating as compared to untrained men. Finally, a greater α- and ß-adrenergic sweating response (both P ≤ .001) was measured in habitually active men than in women. We show that heat exposure augments α-and ß-adrenergic sweating differently via mechanisms associated with altered muscarinic receptor activity. Sex and training status modulate this response.

Does α1-adrenergic receptor blockade modulate sweating during incremental exercise in young endurance-trained men?

PURPOSE: Human eccrine sweat glands respond to α1-adrenergic receptor agonists. We recently reported that adrenergic mechanisms contribute to sweating in endurance-trained men during an incremental exercise to volitional fatigue. However, it remains unclear if this response is mediated by α1-adrenergic receptor activation. METHODS: Twelve endurance-trained men performed an incremental cycling bout until exhaustion while wearing a water-perfused suit to clamp skin temperature at ~ 34 °C. Bilateral forearm sweat rates were measured wherein the distal area was treated with either 1% terazosin (α1-adrenergic receptor antagonist) or saline solution on the opposite limb (Control) via transdermal iontophoresis. We also measured proximal bilateral forearm sweat rate in untreated sites to confirm that no between-limb differences in forearm sweat rate occurred. Once sweat rate returned to pre-exercise resting levels at ~ 20 min postexercise, 0.25% phenylephrine (α1-adrenergic receptor agonist) was iontophoretically administered to skin to verify α1-adrenergic receptor blockade. RESULTS: Sweat rates at the proximal untreated right and left forearm sites were similar during exercise (interaction, P = 0.581). Similarly, no effect of terazosin on sweat rate was measured relative to control site (interaction, P = 0.848). Postexercise administration of phenylephrine increased sweat rate at the control site (0.08 ± 0.09 mg cm-2 min-1), which was suppressed by ~ 90% at the terazosin-treated site (0.01 ± 0.02 mg cm-2 min-1) (P = 0.026), confirming that α1-adrenergic receptor blockade was intact. CONCLUSION: Our findings demonstrate that α1-adrenergic receptors located at eccrine sweat glands do not contribute to eccrine sweating during incremental exercise in young endurance-trained men.

Detection of fluid secretion of three-dimensional reconstructed eccrine sweat glands by magnetic resonance imaging.

We previously showed three-dimensional (3D) reconstructed eccrine sweat glands have similar structures as native eccrine sweat glands, but whether the 3D reconstructed sweat glands appropriately secrete fluid is still unknown. In this study, Matrigel-embedded human eccrine sweat gland cells or Matrigel alone were implanted into the groin subcutis of the nude mice. Ten weeks post-implantation, images of the subcutaneously formed plugs, as well as footpads of rats, pre- and post-pilocarpine/normal saline (NS) injection were acquired using a fat-suppressed proton density-weighted magnetic resonance imaging (MRI) sequence at 7.0 T, and the regions of interest (ROIs) in plugs and rat footpads were analysed and graphed. A significant increase in the ROI mean proton intensity occurred in both 3D reconstructed and native eccrine sweat glands after pilocarpine injection. The mean proton intensity had no noticeable changes in ROIs of Matrigel plugs between pre- and post-pilocarpine injection, and in ROIs of rat footpads between pre- and post-NS injection. In conclusion, the 3D reconstructed sweat glands possess fluid secretion, which is detectable by fat-suppressed proton density-weighted MRI.

The evolution of eccrine sweat gland research towards developing a model for human sweat gland function.

For several decades now, researchers, professional bodies, governments, and journals such as the journal of Experimental Dermatology have worked to reduce the number of animals used in experimentation. This review centres on investigations into how human sweat glands produce sweat and how that research has evolved over the years. It is hoped that this review will show that as methodologies advanced, sweat gland research has come to rely less and less on a variety of animal models as investigative tools and information is being primarily obtained through human and mouse material, with a view to further reductions in using animal models.

Lipoid proteinosis: A case with distinct histopathological and radiological findings.

Lipoid proteinosis is a rare inherited genodermatosis characterized by hyaline deposits in various tissues. Clinically, it manifests with cutaneous as well as extracutaneous features. Periodic acid-Schiff (PAS)-reactive hyaline deposits in the upper dermis, with localization around blood vessels and eccrine sweat glands, in particular, is the histopathological hallmark finding. On brain imaging, bilateral symmetrical temporal lobe calcifications are considered to be pathognomonic of this disorder. We report a case of lipoid proteinosis in which hyaline deposits were present in the papillary and reticular dermis, without being seen at the periphery of eccrine sweat glands, along with dystrophic calcification. Magnetic resonance imaging (MRI) of brain revealed hydrocephalus, subependymal heterotropia and absent splenium of corpus callosum with no evidence of temporal lobe calcification. Thus, our case highlights the inherent diverse nature of lipoid proteinosis.

Pitted keratolysis, erythromycin, and hyperhidrosis.

Pitted keratolysis (PK) is a plantar skin disorder mainly caused by coryneform bacteria. A common treatment consists of the topical use of erythromycin. Hyperhidrosis is considered a predisposing factor for bacterial proliferation and, consequently, for the onset of PK. The aim of this study was to evaluate the relationship between PK erythromycin and hyperhidrosis. All patients with PK seen in Sant'Andrea Hospital, between January 2009 and December 2011, were collected. PK was clinically and microscopically diagnosed. All patients underwent only topical treatment with erythromycin 3% gel twice daily. At the beginning of the study and after 5 and 10 days of treatment, a clinical evaluation and a gravimetric measurement of plantar sweating were assessed. A total of 97 patients were diagnosed as PK and were included in the study. Gravimetric measurements showed that in 94 of 97 examined patients (96.90%) at the time of the diagnosis, there was a bilateral excessive sweating occurring specifically in the areas affected by PK. After 10 days of antibiotic therapy, hyperhidrosis regressed together with the clinical manifestations. According to these data, we hypothesize that hyperhidrosis is due to an eccrine sweat gland hyperfunction, probably secondary to bacterial infection.

Pretreatment of microneedles enhances passive transdermal administration of pilocarpine and pilocarpine-induced sweat production in humans.

The development of an effective transdermal drug delivery protocol to eccrine sweat glands is important for the advancement of research on the human sweating response. We investigated whether microneedle treatment prior to the application of pilocarpine, a hydrophilic and sudorific agent that does not induce sweating due to a limited percutaneous passive diffusion by skin application alone, augments sweat production. We applied three microneedle arrays to forearm skin sites simultaneously (n = 20). Upon removal of the microneedles, 1 % pilocarpine was applied to each site for 5-, 15-, and 30-min for the assessment of sweat gland function. In parallel, pilocarpine was administered by transdermal iontophoresis (5-min) at a separate site. Sweat rate was assessed continuously via the ventilated capsule technique. Pilocarpine augmented sweat rate at the 15- and 30-min periods as compared to the application at 5-min. The sweating responses induced by the 15- and 30-min application of pilocarpine were equivalent to âˆ¼ 80 % of that measured at the iontophoretically treated sites. Notably, we observed a correlation in sweat rate between these two transdermal drug delivery methods. Altogether, our findings show that pre-treatment of microneedle arrays can enhance transdermal delivery efficiency of pilocarpine to human eccrine sweat glands.

Epidermal and dermal cells from adult rat eccrine sweat gland-containing skin can reconstruct the three-dimensional structure of eccrine sweat glands.

BACKGROUND: Previously, we have demonstrated that eccrine sweat gland cells (ESGCs) can reconstruct the three-dimensional (3D) structure of eccrine sweat glands (ESGs). However, there is still a need to explore source cells capable of regenerating ESG to address the issue of ESG regeneration in ESGC-deficient conditions, such as severe burns. METHODS: The epidermal cells and dermal cells in adult rat ventral foot skin (ESG-bearing) were isolated. The isolated single epidermal cells and dermal cells were mixed with Matrigel, and then the mixture was implanted into the axillary/inguinal fat pads of nude mice. Five weeks after implantation, the Matrigel plugs were harvested and the morphology and differentiation of the cells were examined by H&E staining and fluorescent immunohistochemical staining for ESG markers, such as Na+ -K+ -2Cl- cotransporter 1 (NKCC1), Na+ -K+ -ATPase (NKA), Foxa1 and K14. RESULTS: The epidermal cells and dermal cells of adult rat ventral foot skin can reconstruct 3D structure and express specific markers of ESGs in skin, such as NKCC1, NKA and Foxa1, indicating the ESG-phenotypic differentiation of the 3D structures. Double immunofluorescence staining showed that some 3D structures expressed both the myoepithelial cell marker alpha-SMA and the common marker K14 of duct cells and myoepithelial cells, while some 3D structures expressed only K14, indicating that ESG-like 3D structures differentiated into duct-like and secretory coiled cells. CONCLUSION: Epidermal and dermal cells from adult ESG-bearing skin can be used as a cell source for ESG regeneration.

Chromhidrosis Linked to Personal Care Products.

Eccrine chromhidrosis (CH) is a rare condition characterized by the excretion of colored sweat from eccrine glands. This case report contributes to the medical literature by highlighting two instances of eccrine CH linked to over-the-counter personal care products, an association not previously documented. These products contained FD&C Blue No. 1, D&C Red No. 33, and Ext. D&C Violet No. 2, which are known colorants in various consumer items. These cases underscore the potential for personal care products containing colored dyes to cause eccrine CH. The medical community and consumers must be vigilant about product ingredients to facilitate an accurate diagnosis and promote informed usage. Healthcare professionals should consider the role of colored personal care products in their differential diagnosis of CH to recognize and address potential risks effectively. These cases emphasize the need to actively include colored personal care products in medical considerations to ensure that healthcare practices and consumer awareness properly recognize and address potential risks associated with these products.

Crimson Tears: A Rare Case of Hematohidrosis.

Hematohidrosis is a rare clinical disorder characterized by oozing blood from intact skin and mucous membranes in the absence of a bleeding disorder. Most of the cases reported are from Asia. Although etiopathogenesis is unclear, it has been strongly linked to psychological stress. A nine-year-old girl was brought to the hospital with multiple episodes of painless bleeding from her nose and mouth for four days and eyes for three days, lasting four to five minutes each. Her symptoms and a thorough but unrevealing workup, including brain imaging, led to a clinical diagnosis of hematohidrosis, with parental disharmony as the underlying stress factor. Family therapy was recommended, and parent management training regarding the positive and negative reinforcement techniques was given. A significant improvement was observed at her one-month follow-up. This case adds to the current limited literature on hematohidrosis, highlighting its association with psychological stress and the importance of a multidisciplinary approach to management. Future research is warranted to elucidate molecular pathways involved in stress-induced vascular dysfunction and explore targeted therapeutic interventions.

Establishment of a conditionally reprogrammed primary eccrine sweat gland culture for evaluation of tissue-specific CFTR function.

BACKGROUND: Sweat chloride concentration is used both for CF diagnosis and for tracking CFTR modulator efficacy over time, but the relationship between sweat chloride and lung health is heterogeneous and informed by CFTR genotype. Here, we endeavored to characterize ion transport in eccrine sweat glands (ESGs). METHODS: First, ESGs were microdissected from a non-CF skin donor to analyze individual glands. We established primary cultures of ESG cells via conditional reprogramming for functional testing of ion transport by short circuit current measurement and examined cell composition by single-cell RNA-sequencing (scRNA-seq) comparing with whole dissociated ESGs. Secondly, we cultured nasal epithelial (NE) cells and ESGs from two people with CF (pwCF) to assess modulator efficacy. Finally, NEs and ESGs were grown from one person with the CFTR genotype F312del/F508del to explore genotype-phenotype heterogeneity. RESULTS: ESG primary cells from individuals without CF demonstrated robust ENaC and CFTR function. scRNA-seq demonstrated both secretory and ductal ESG markers in cultured ESG cells. In both NEs and ESGs from pwCF homozygous for F508del, minimal baseline CFTR function was observed, and treatment with CFTR modulators significantly enhanced function. Notably, NEs from an individual bearing F312del/F508del exhibited significant baseline CFTR function, whereas ESGs from the same person displayed minimal CFTR function, consistent with observed phenotype. CONCLUSIONS: This study has established a novel primary culture technique for ESGs that allows for functional ion transport measurement to assess modulator efficacy and evaluate genotype-phenoytpe heterogeneity. To our knowledge, this is the first reported application of conditional reprogramming and scRNA-seq of microdissected ESGs.

Pregnancy-Related Eccrine Angiomatous Hamartoma: Case Report.

Eccrine angiomatous hamartoma is rare, slow-growing, and benign neoplasm that is diagnosed based on clinical characteristics and histological findings. It usually presents as a solitary nodule on the extremities and may arise at birth or in childhood. Although it is usually asymptomatic, in some cases it can cause pain and hyperhidrosis. From a histological perspective, it is characterized by an increase in the number of eccrine glands and a proliferation of vascular channels. We present the case of a 26-year-old woman who developed an eccrine angiomatous hamartoma in her right leg. The rapid growth of the lesion during pregnancy coupled with the challenges posed by a superficial biopsy, complicated the differential diagnosis.

FGF7 and FGF10 Promote Fate Transition of Human Epidermal Cell-derived Organoids to an Eccrine Gland Phenotype.

Rationale: Reconstruction of hair follicles (HFs) and eccrine sweat glands (ESGs) is essential for functional skin regeneration. In skin reconstruction research, we found that foreskin-derived epidermal cells reconstructed HF organoids unidirectionally, but not ESG organoids. Methods: To investigate key genes and pathways influencing the fate of ESG and HF, a transcriptome profiling of ESG placode-containing skin and HF placode-containing skin was employed, and key DEGs were identified and validated by RT-qPCR and immunofluorescence staining in mice and rats. Subsequently, adult human epidermal cell-derived organoids were reconstructed to probe functional roles and mechanisms of FGF7 and FGF10 by series of approaches integrating RT-qPCR, immunofluorescence-staining, WB, apoptosis assay, and pathway interference assay. Results: All members of FGF7 subfamily were among the key DEGs screened, the differential expression of FGF7 and FGF10 and their receptors FGFR1/FGFR2 was verified between ESG placode-containing skin and HF placode-containing skin. In vivo and in vitro Matrigel plug models showed that both FGF7 and FGF10 promoted fate transition of human epidermal cell-derived organoids to ESG phenotype organoids, FGF7 and FGF10 had a synergistic effect, and mainly function through the FGFR1/2-MEK1/2-ERK1/2 pathway. Conclusions: Adult epidermal cells can be manipulated to reconstruct personalized HF and ESG to meet different needs.

In vivo assessments of microneedle arrays and iontophoresis of pilocarpine in human palmar sweating.

Emotional stress-induced sweating in glabrous skin of the palm and sole, which can be excessive in some individuals (hyperhidrosis), can negatively impact quality of life. Understanding the mechanisms underlying this response can lead to potential treatments. Transdermal iontophoresis is a method to administer ionized sudorific agents to sweat glands within the dermis. However, due to the reduced permeability of pharmacological agents in thicker skin such as the palms, this technique has been shown to be less effective when applied in thicker skin. Thus, we assessed the effectiveness of pre-treating palmar skin with microneedles to create micropores on the stratum corneum of the palm to enhance the iontophoretic delivery of pilocarpine to modulate sweat production. On three separate sessions, we applied microneedles (0.78 cm2, 190 needles with a length of 875 µm) to palm and forearm skin sites. Upon removal of the microneedles, we assessed the number of perforations colored by gentian violet in the forearm only (Protocol 1, n = 20), skin barrier function indexed by transepidermal water loss (TEWL) (Protocol 2, n = 21), and sweating induced by the iontophoretic application of 1% pilocarpine (Protocol 3, n = 43). Briefly, we measured 1) ∼172 dyed spots on forearm skin, 2) an increase of ∼300% and âˆ¼ 900% in TEWL on palm and forearm skin, respectively; and 3) a 2-fold increase in sweating on the palm only following the application of the microneedles. Notably, the microneedle array failed to enhance pilocarpine delivery at either the palm or forearm skin sites. We showed the application of a microneedle array enhanced skin permeability and sweat production on the palm without a concomitant increase in pilocarpine delivery. Therefore, this methodology could be employed to advance our understanding of the causes and treatments of medical conditions such as hyperhidrosis.

Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of rat eccrine sweat glands.

BACKGROUND: Each eccrine sweat gland (ESG) is a single-tubular structure with a central lumen, and the formation of hollow lumen in the initial solid cell mass is a key developmental process. To date, there are no reports on the mechanism of native ESG lumen formation. METHODS: To investigate the lumen morphogenesis and the lumen formation mechanisms of Sprague-Dawley (SD) rat ESGs, SD rat hind-footpads at E20.5, P1-P5, P7, P9, P12, P21, P28 and P56 were obtained. The lumen morphogenesis of ESGs was examined by HE staining and immunofluorescence staining for polarity markers. The possible mechanisms of lumen formation were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay and autophagy marker LC3B immunofluorescence staining, and further explored by ouabain intervention experiment. RESULTS: In SD rat ESGs, the microlumen was formed at P1, and the small intact lumen with apical-basal polarity appeared at P3. The expression of apical marker F-actin, basal marker Laminin, basolateral marker E-cadherin was consistent with the timing of lumen formation of SD rat ESGs. During rat ESG development, apoptosis and autophagy were not detected. However, inhibition of Na+-K+-ATPase (NKA) with ouabain resulted in decreased lumen size, although neither the timing of lumen formation nor the expression of polarity proteins was altered. CONCLUSIONS: Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of SD rat ESGs. NKA-regulated fluid accumulation drives lumen expansion.

Case Report and Review of the Pathophysiology and Therapeutics of Adult Hematohidrosis.

Hematohidrosis is an extremely rare condition characterized by the oozing or secretion of blood through intact skin and mucosa, particularly through eccrine glands. Although there is not much literature available on the condition, examples of Hematohidrosis include the crying and sweating of blood. The fluid may have a bloody tinge or may be frank blood. The anomaly has no identifiable etiology, and patients generally present in a good state of health. In this report, we present a 19-year-old female who had weekly occurrences of bloody diaphoresis that had been present consistently for one year. During her presentation at the hematology clinic, she was investigated thoroughly for alternative causes, but none were found. The patient was diagnosed with hematohidrosis and was offered treatment with propranolol, which she declined. She continues to follow up routinely in the hematology clinic with persistent symptoms.

Notch1 down-regulation in lineage-restricted niches is involved in the development of mouse eccrine sweat glands.

Eccrine sweat gland (SG) restrictedly exists in mouse foot pads indicating that mouse plantar dermis (PD) contains the SG lineage-restricted niches. However, it is still unclear how these niches can affect stem cell fate towards SG. In this study, we tried to find the key cues by which stem cells sense and interact with the SG lineage-specific niches both in vivo and in vitro. Firstly, we used transcriptomics RNA sequencing analysis to screen differentially expressed genes between SG cells and epidermal stem cells (ES), and used proteomic analysis to screen differentially expressed proteins between PD and dorsal dermis (DD). Notch1 was found differentially expressed in both gene and protein levels, and was closely related to SG morphogenesis based on Gene Ontology (GO) enrichment analysis. Secondly, the spatial-temporal changes of Notch1 during embryonic and post-natal development of SG were detected. Thirdly, mouse mesenchymal stem cells (MSCs) were introduced into SG-like cells in vitro in order to further verify the possible roles of Notch1. Results revealed that Notch1 was continuously down-regulated along with the process of SG morphogenesis in vivo, and also along with the process that MSCs differentiated into SG-like cells in vitro. Hence, we suggest that Notch1 possibly acts as with roles of "gatekeeper" during SG development and regulates the interactions between stem cells and the SG lineage-specific niches. This study might help for understanding mechanisms of embryonic SG organogenesis.