Biologic Structure and Function: Perspectives on Morphologic Approaches to the Study of the Granular Layer Keratinocyte.

Abstract

S tephen Rothman [1] wrote: "Modern dermatology has been built on the solid pillars of precise macro-and microscopic observation, accurate recording and meaningful interpretation ofthe findings. No natural science can exist without direct observation of natural phenomena, and dermatology has become a great discipline because we have had so many good observers." He went on to state further that "... whereas the immense knowledge acquired by the classical descriptive methods is still rapidly increasing, the application of experimental methods to dermatologic problems is a relatively young and undeveloped approach." These statements acknowledge the importance of observation and description (usually thought of as features of morphology) in clinical dermatology and in descriptive dermatologic research, but were made before he could recognize the value of morphology to experimental studies as well. Unfortunately, Dr. Rothman did not see the remarkable expansion in dermatologic research that has taken place within even the last 20 years, an eta in which descriptive biology and experimental biology are not necessarily separate entities or even parallel concepts. Morphology is simply one of many approaches --sets of tools -that can be used to solve problems in biology.Morphology is often the starting point of an investigation. Understanding the structure of a cell or tissue provides a framework on which other kinds of data can be applied. A morphologic study, however, need not be synonomous with description and qualitative investigation. Many ofthe techniques used by morphologists provide compositional information (presence/absence of a chemical compound) on a structural substrate (location within the cell or tissue) which, in turn, permits interpretation of function. For example, electron microscopic autoradiography can be used to identify the site of incorporation of a radiolabeled amino acid within the tissue and the specific cell and organelle in which it is utilized, or x-ray microanalysis can reveal the elemental composition of parts of cells or different cells within a tissue. Through the use of techniques like morphometry and stereology, morphologic studies can also be quantitative. To continue the example from above, the volume density ofthe radiolabeled organelte can he determined for a cell or tissue by means of selective sampling and prescribed methods of counting, thus allowing for quantitation and statistical analysis when comparing experimental data. Morphology should not have the limited connotation of providing purely descriptive information.The structure and composition of a tissue can provide insight into its function. As stated by Braverman and Braverman [2], "a major aim of biological work is to correlate structure with function in order to understand how tissues work." The goal in the present paper, as indicated by its title, is to support this statement as we review the use of morphologic approaches to understand skin hiology, selecting as an illustration the progress that has been made in understan...

MDM2 overexpression generates a skin phenotype in both wild type and p53 null mice

“…Thickening was systematically observed in at least thirty animals, with skin from dierent places, including the back, the head, the tail and the abdomen. Within the epidermis, the granular layer was noticeably dierent, consisting of more cell layers with granules but with less granules per cell than normal skin ( Figure 4a, see arrows) (Holbrook, 1989). There was no evidence of enlarged cells with giant nuclei or multinucleated cells (Lundgren et al, 1997).…”

Ultrastructural pattern of loricrin localization in the epidermis of the red kangarooMacropus rufus(Marsupialia, Mammalia) in relation to the formation of stratum corneum in mammalian epidermis

“…The softness of the mammalian epidermis has been related to the evolution of a granular layer containing keratohyaline granules that allow the production of a pliable stratum corneum (Spearman 1964;Maderson 2003). In the epidermis of mouse, keratinocytes of the stratum granulosum contain keratohyaline granules that are distinguished into irregularly shaped F-granules, L-granules, and composite granules (Holbrook 1989;Steven et al 1990;Resing & Dale 1991;Dale et al 1994;Hardman et al 1998). However, the above morphology for keratohyalin granules is not common in the epidermis of other mammalian species, especially for L-granules, typically present in the mouse epidermis but that are *Correspondence: Dipartimento di Biologia evoluzionistica sperimentale, University of Bologna, via Selmi 3, 40126 Bologna, Italy.…”

“…Fax: +39 051 209 4286. Email: alibardi@biblio.cib.unibo.it often absent in other species, namely humans, rat and platypus (Holbrook 1989;Steven et al 1990;Yoneda et al 1992;Alibardi 2009Alibardi , 2010.…”

“…Filaggrin and sometimes also trichohyalin are present in F-granules of keratohyaline granules where these proteins form a large part of the matrix material present in mature corneocytes (Holbrook 1989;Steven et al 1990;Resing & Dale 1991;Manabe & O'Guin 1994;Hardman et al 1998). Other corneous protein precursors such as involucrin and the major corneous protein loricrin are mainly deposited along the plasmalemma to produce the resistant cell corneous envelope of mature corneocytes (Kalinin et al 2002).…”

Interleukin 1 Alpha and Beta in Psoriatic Skin: Enzymoimmunoassay, Immunoblot Studies and Effect of Systemic Retinoids

“…This indicated that a pool of preformed IL-1 existed herein that was subsequently localized by immunohistochemical and immunoclectron microscopy to distinct stages in the differentiation program of the epidermis [6]. Differentia tion of the kératinocytes is a complex process which in cludes several stages from a stem cell population |7] to a 1 This work was supported in part by grants from the Fonds National Suisse pour la Recherche Scientifique (3. fully anuclcated cell [8]; in this respect the process has been compared to that of the red blood cells lineage. It is interesting in this context that IL-1 is now known as being identical to hemopoietin I.a factor that enhances the pro duction of hemopoietic progenitor cells from stem cells and their subsequent proliferation in response to colony stimulating factor [1,2].…”