Letters to the Editor

LETTERS TO THE EDITOR Dear Sir: In the first issue of this welcome newjournal an article by R.J. Williams, "Normal Young Men," proposed that the collection ofcertain data onthe young would be helpful inestabkshing theetiology ofmanydiseasesofthe old. Thissuggestionseemed promising to us in view ofour own work. Perhaps Dr.Williams and some ofyour readers will be interested in our delayed response. In the past few years we have studied a number oftissue variables which can be measured in human beings. Our figures suggested that some ofthese variables may be biological constants in almost the meaning that physiologists give to this term. That is, the variable has a characteristic distribution around the mean ofeach species, and every individual is characterized by his place in relation to the mean ofhis species.Whereas the familiar physiological constants like temperature and basal metabolic rate, or anatomical constants such as body height and even weight, have a relatively narrow range, most of our variables had considerable range ofvariation. This seemed to us to confirm Williams' dictum: "The idea that any individual human being has a makeup such that every organ, gland, and structure in his body is about average is untenable." (Our italics.) Our work dealt with the average size ofepithelial cells (1-3), the deposition ofglycogeninunkeratinized and keratinized epithelia (1), the thickness ofthe cellular layer (4, 5), and the rate ofcell turnover in homologous regions ofstratified epithelia (3, 4). The following is a briefsummary ofthe case which can be made for each ofthese in support of Williams' thesis. Cell size.—Estimates of average cell size were made in various regions of oral epithelium in men and in mice by counting the numbers ofcells contained in measured areas of histological sections. This approximation disregards the third dimension, but in the regions we studied, the cell counts are identical in all planes ofsectioning which are perpendicular to the surface, and the reciprocals ofthe cell densities may be taken as indices ofaverage cell size. The averageepithelial cellsize so estimatedshowed wide regional variations, especially between unkeratinized and keratinized epithelium in the human and between epithelia with different types ofkeratinization in the mouse. In two different sets ofabout 50 human biopsyspecimenseach,homologousregionsvariedover morethanatwofoldrange. There was distinct bilateral symmetry ofthe intra-individual cell size in two discrete regions of 128 Letters to the Editor Perspectives in Biology and Medicine · Autumn i960 the oral cavity, but we cannot yet say whether the cell size determined in one tissue ofan individual characterizes this tissue alone or the individual as a whole. The cell size ofhuman oral epithelia undergoes a change with age which is probably quite regular. The ceU counts increase by a third between the ages ofabout 30 and about 60 years; this is partly accounted for by a loss ofwater. The range ofsizes is greater inthe older age group. The wide ranges ofregional and inter-individual variation are particularly interesting in view ofthe many attempts to estabhsh the change of cell size characteristic for malignant neoplasia (6). Glycogen deposits in stratified epithelia.—Histochemically demonstrable amounts of glycogen occur in unkeratinized stratified epithelia, e.g., in the vagina and in the epithehum ofthe buccal and alveolar mucosa. Gierke found that the deposits in epithelia are resistant to mobilization in hypoglycemia and came to the conclusion that glycogen is an "integral part of the makeup of these cells" (7). Yet glycogen serves no evident local metabolicfunction, being preserved inthe superficialexfoUating celllayers. We suggested that the glycogen deposits in unkeratinized epithelia may have a structural role in the maintenance ofthe shape ofthe cells. Rough quantitative estimates made by microscopic inspection ofsections ofhuman biopsies showed bilateral symmetry of quantity, and also a high positive correlation betweenthe amounts ofglycogen on the same side which were deposited in differentregions ofthe oral cavity. In specimens with large deposits, even keratinizing regions adjacent to the unkeratinizing part contained glycogen, although ordinarily keratinizing epithelia are freeofhistochemicallydemonstrable glycogen. Almost allexceptions to bilateralsymmetry and to the similarity of different regions on the same side occurred in cases of underlying inflammation, which, it is well known, leads to increased glycogen content of epitheha. Inflammation ofthe mucosa is a rather common event in the oral cavity, and since it has no tendency for...