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D.A. Samuelson, K.C. Ganesh, S.M. Miles, A.Z. Zivotofsky, D. Zivotofsky, P.A. Lewis; Morphology and Histochemistry of Bowman’s Layer in Selected Vertebrates . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2181.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Our understanding of the Bowman’s layer in the vertebrate eye is limited to that described in primates and birds. Recently, we have discovered similar structures in the giraffe (Giraffa camelopardalis) and two spp of whales (Tursiops truncatus, dolphin, and Globiocephela macrorhynchus, pilot whale). Knowledge of Bowman’s layer especially with regard to the role that this structure plays in the corneas of these species is limited. To that end, we have begun to investigate the morphology and histochemistry of Bowman’s layer in eyes of the giraffe, the two mentioned whale spp, the chicken and monkey. Methods: Formalin–preserved specimens from anterior eyes of two or more individuals of the adult giraffe, bottle–nosed dolphin, pilot whale, domestic chicken and macaque monkey were embedded and sectioned sagittally and treated with a variety of stains that included: H&E, Masson’s trichrome, PAS, elastin stain, heparan sulfate proteoglycan antibody, and a battery of lectins (asparagus pea lectin, wheat germ agglutinin, Concanavalin agglutinin, Dolichos biflorus lectin, Bandeiraea simplicifolia agglutinin). Results: The thickness of Bowman’s layer was 4–8 microns in the giraffe, monkey and chicken and 16–22 microns in the whale spp. The construction of Bowman’s layer appeared nearly identical among the species as viewed by sections stained with H&E and trichrome, having been homogenous and acellular. In the monkey, chicken and giraffe the staining intensity was similar to that of the adjacent stroma, having differed only in the whale spp. Concomitantly, there was an absence of staining for elastic fibers in Bowman’s layer of the land–based animals, having been present in both marine mammals. Bowman’s layers of all spp. possessed PAS–positive anterior margins. Among the lectins, wheat germ agglutinin reacted positively only with Bowman’s layer of the two whale spp. The rest of the lectins reacted weakly or inconclusively with Bowman’s layer of all spp.Conclusions: Bowman’s layer of the land–based spp. share similarities in size, morphology and histochemistry, differing substantially from that of marine mammals, which may reflect a variation of roles that this structure plays. Further analysis, especially with regard to collagen composition and ultrastructural appearance, is warranted.
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