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A unique lineage gives rise to the meibomian gland.

Call M, Fischesser K, Lunn MO, Kao WW - Mol. Vis. (2016)

Bottom Line: This colocalization region decreased as the gland developed becoming restricted to the central duct near the opening to the acini in the fully developed gland.This unique group of cells was located in the central duct with a concentration near the ductule orifice.The expression of these cells reduced during meibomian gland morphogenesis and may play a role in the development and homeostasis of the gland.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University of Cincinnati, Cincinnati OH.

ABSTRACT

Purpose: To identify the lineage that contributes to the morphogenesis of the meibomian gland.

Methods: To examine which cell lineage gives rise to the meibomian gland, the expression of Pax6 as well as that of various cytokeratin markers, including keratin 14 (Krt14), Krt15, Krt4, and Krt10, was examined with immunofluorescent staining of C57BL/6J mouse eyelids from P2 to P11 pups and adult mice.

Results: Pax6 was localized to the cytoplasm within the acinar region of the meibomian glands during morphogenesis but was absent in the fully developed gland. Keratin 14 was expressed throughout the gland at all stages whereas keratin 15 was absent at all stages. Keratin 4, a marker of mucosal lineage, was present throughout the gland and was colocalized with keratin 10 (epidermal lineage marker) in the developing duct at P4. This colocalization region decreased as the gland developed becoming restricted to the central duct near the opening to the acini in the fully developed gland.

Conclusions: We identified a unique cell lineage that expresses markers characteristic of mucosal and epidermal epithelia during meibomian gland morphogenesis. This unique group of cells was located in the central duct with a concentration near the ductule orifice. The expression of these cells reduced during meibomian gland morphogenesis and may play a role in the development and homeostasis of the gland.

No MeSH data available.


Related in: MedlinePlus

A unique cell lineage expressing Krt4 and Krt10. Horizontal sections of eyelids double stained with keratin 4 (Krt4; red) and Krt10 (green) at P4 (A, B), P11 (C, D), and adult (E, F). Regions of colocalization were determined using the Coloc 2 plug-in for the Fiji software package. Colocalized regions are shown in white at P4 (B), P11 (D) and adult (F). At P4, colocalization of Krt4 and Krt10 is found in the developing central duct as well as the distal gland region. By P11, the colocalization region is restricted to the central duct and is absent from the acini. In the fully developed meibomian gland (adult), areas of colocalization are found within the central duct near the ductule openings. EP = epidermis; MCJ = mucocutaneous junction; CJ = conjunctiva; AC = acinus; asterisk = central duct.
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f4: A unique cell lineage expressing Krt4 and Krt10. Horizontal sections of eyelids double stained with keratin 4 (Krt4; red) and Krt10 (green) at P4 (A, B), P11 (C, D), and adult (E, F). Regions of colocalization were determined using the Coloc 2 plug-in for the Fiji software package. Colocalized regions are shown in white at P4 (B), P11 (D) and adult (F). At P4, colocalization of Krt4 and Krt10 is found in the developing central duct as well as the distal gland region. By P11, the colocalization region is restricted to the central duct and is absent from the acini. In the fully developed meibomian gland (adult), areas of colocalization are found within the central duct near the ductule openings. EP = epidermis; MCJ = mucocutaneous junction; CJ = conjunctiva; AC = acinus; asterisk = central duct.

Mentions: To examine more specifically the cell lineage giving rise to the meibomian gland and to expand on past research examining keratin expression only in the adult gland, we focused on two markers, Krt4 and Krt10, which stain mucosa epithelia and epidermal epithelia, respectively. In the fully developed meibomian gland (P21), Krt4 expression was present within the conjunctiva, hair follicles, and meibomian gland whereas Krt10 was restricted to the epidermis (Figure 3A). Given the exclusive nature of these two keratins in the fully developed meibomian gland, we set out to examine their expression pattern during development of the gland. Double immunofluorescent staining at P2 revealed expression of Krt4 and Krt10 within the elongated epidermal invagination (Figure 3B). Colocalization analysis using Fiji revealed that only 8% of the Krt10-positive cells colocalized with the Krt4-positive cells (Mander’s overlap coefficient: M1 = 0.1992; M2 = 0.0841). These cells were located at the base of the invaginating epidermis (Figure 3B). At P4, the meibomian gland continued to elongate with Krt10 expression predominantly in the epidermis and the invaginating central duct and distal region of the gland. Krt4 was expressed throughout the developing gland with regions of colocalization (Mander’s overlap coefficient: M1 = 0.993; M2 = 0.909) in the central canal as well as the distal gland region (Figure 3B–C, Figure 4A,B). By P11, Krt10 expression was restricted to the central duct and was absent from the acini. As in the previous two stages, Krt4 expression was present throughout the gland (Figure 3B–C). The Krt4 and Krt10 colocalization region was also restricted to the cells lining a portion of the central duct (Mander’s overlap coefficient: M1 = 0.981; M2 = 0.993; Figure 4C,D). The colocalization region became further restricted in the fully developed meibomian gland of an adult, with only a few cells expressing Krt4 and Krt10 (Mander’s overlap coefficient: M1 = 0.728; M2 = 0.732). The central duct of the adult meibomian gland expressed low levels of Krt10 with Krt4 expression being predominant. The small ductules and acini expressed Krt4 but lacked Krt10 expression (Figure 4E,F). To determine whether cells that expressed Krt4 and Krt10 were also undergoing proliferation, Ki67 immunostaining was performed on P9 and P11 eyelids. Ki67 staining was present in the cells surrounding the central duct and acini but was absent in the Krt4- and Krt10-positive cells (Figure 5).


A unique lineage gives rise to the meibomian gland.

Call M, Fischesser K, Lunn MO, Kao WW - Mol. Vis. (2016)

A unique cell lineage expressing Krt4 and Krt10. Horizontal sections of eyelids double stained with keratin 4 (Krt4; red) and Krt10 (green) at P4 (A, B), P11 (C, D), and adult (E, F). Regions of colocalization were determined using the Coloc 2 plug-in for the Fiji software package. Colocalized regions are shown in white at P4 (B), P11 (D) and adult (F). At P4, colocalization of Krt4 and Krt10 is found in the developing central duct as well as the distal gland region. By P11, the colocalization region is restricted to the central duct and is absent from the acini. In the fully developed meibomian gland (adult), areas of colocalization are found within the central duct near the ductule openings. EP = epidermis; MCJ = mucocutaneous junction; CJ = conjunctiva; AC = acinus; asterisk = central duct.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764607&req=5

f4: A unique cell lineage expressing Krt4 and Krt10. Horizontal sections of eyelids double stained with keratin 4 (Krt4; red) and Krt10 (green) at P4 (A, B), P11 (C, D), and adult (E, F). Regions of colocalization were determined using the Coloc 2 plug-in for the Fiji software package. Colocalized regions are shown in white at P4 (B), P11 (D) and adult (F). At P4, colocalization of Krt4 and Krt10 is found in the developing central duct as well as the distal gland region. By P11, the colocalization region is restricted to the central duct and is absent from the acini. In the fully developed meibomian gland (adult), areas of colocalization are found within the central duct near the ductule openings. EP = epidermis; MCJ = mucocutaneous junction; CJ = conjunctiva; AC = acinus; asterisk = central duct.
Mentions: To examine more specifically the cell lineage giving rise to the meibomian gland and to expand on past research examining keratin expression only in the adult gland, we focused on two markers, Krt4 and Krt10, which stain mucosa epithelia and epidermal epithelia, respectively. In the fully developed meibomian gland (P21), Krt4 expression was present within the conjunctiva, hair follicles, and meibomian gland whereas Krt10 was restricted to the epidermis (Figure 3A). Given the exclusive nature of these two keratins in the fully developed meibomian gland, we set out to examine their expression pattern during development of the gland. Double immunofluorescent staining at P2 revealed expression of Krt4 and Krt10 within the elongated epidermal invagination (Figure 3B). Colocalization analysis using Fiji revealed that only 8% of the Krt10-positive cells colocalized with the Krt4-positive cells (Mander’s overlap coefficient: M1 = 0.1992; M2 = 0.0841). These cells were located at the base of the invaginating epidermis (Figure 3B). At P4, the meibomian gland continued to elongate with Krt10 expression predominantly in the epidermis and the invaginating central duct and distal region of the gland. Krt4 was expressed throughout the developing gland with regions of colocalization (Mander’s overlap coefficient: M1 = 0.993; M2 = 0.909) in the central canal as well as the distal gland region (Figure 3B–C, Figure 4A,B). By P11, Krt10 expression was restricted to the central duct and was absent from the acini. As in the previous two stages, Krt4 expression was present throughout the gland (Figure 3B–C). The Krt4 and Krt10 colocalization region was also restricted to the cells lining a portion of the central duct (Mander’s overlap coefficient: M1 = 0.981; M2 = 0.993; Figure 4C,D). The colocalization region became further restricted in the fully developed meibomian gland of an adult, with only a few cells expressing Krt4 and Krt10 (Mander’s overlap coefficient: M1 = 0.728; M2 = 0.732). The central duct of the adult meibomian gland expressed low levels of Krt10 with Krt4 expression being predominant. The small ductules and acini expressed Krt4 but lacked Krt10 expression (Figure 4E,F). To determine whether cells that expressed Krt4 and Krt10 were also undergoing proliferation, Ki67 immunostaining was performed on P9 and P11 eyelids. Ki67 staining was present in the cells surrounding the central duct and acini but was absent in the Krt4- and Krt10-positive cells (Figure 5).

Bottom Line: This colocalization region decreased as the gland developed becoming restricted to the central duct near the opening to the acini in the fully developed gland.This unique group of cells was located in the central duct with a concentration near the ductule orifice.The expression of these cells reduced during meibomian gland morphogenesis and may play a role in the development and homeostasis of the gland.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, University of Cincinnati, Cincinnati OH.

ABSTRACT

Purpose: To identify the lineage that contributes to the morphogenesis of the meibomian gland.

Methods: To examine which cell lineage gives rise to the meibomian gland, the expression of Pax6 as well as that of various cytokeratin markers, including keratin 14 (Krt14), Krt15, Krt4, and Krt10, was examined with immunofluorescent staining of C57BL/6J mouse eyelids from P2 to P11 pups and adult mice.

Results: Pax6 was localized to the cytoplasm within the acinar region of the meibomian glands during morphogenesis but was absent in the fully developed gland. Keratin 14 was expressed throughout the gland at all stages whereas keratin 15 was absent at all stages. Keratin 4, a marker of mucosal lineage, was present throughout the gland and was colocalized with keratin 10 (epidermal lineage marker) in the developing duct at P4. This colocalization region decreased as the gland developed becoming restricted to the central duct near the opening to the acini in the fully developed gland.

Conclusions: We identified a unique cell lineage that expresses markers characteristic of mucosal and epidermal epithelia during meibomian gland morphogenesis. This unique group of cells was located in the central duct with a concentration near the ductule orifice. The expression of these cells reduced during meibomian gland morphogenesis and may play a role in the development and homeostasis of the gland.

No MeSH data available.


Related in: MedlinePlus