. The elements of pathological histology with special reference to practical methods . ations in thetympanum, and consist in most cases of a more or less vascularround-celled tissue. Next in frequency to these round-celled polypicome the fibrous varieties, into which the former may pass by anorganisation of the granulation tissue, w^hich begins along the vesselsin the central parts of the tumours. Less common are the cavernouspolypi, which develop out of the two first-named forms when thenew formation of vessels prevails at the expense of the interstitialsubstance; whilst the myxomatous polypi
. The elements of pathological histology with special reference to practical methods . ations in thetympanum, and consist in most cases of a more or less vascularround-celled tissue. Next in frequency to these round-celled polypicome the fibrous varieties, into which the former may pass by anorganisation of the granulation tissue, w^hich begins along the vesselsin the central parts of the tumours. Less common are the cavernouspolypi, which develop out of the two first-named forms when thenew formation of vessels prevails at the expense of the interstitialsubstance; whilst the myxomatous polypi are the rarest of all. POL ypi 481 The epithelium of the small polypi is mostly cylindrical andstratified, and only passes into a stratified squamous form whenthe tumours grow further into the external meatus. If we thenexamine such polypi from the root to the apex of the portionlying in the meatus, we find in the first place a stratified ciliatedepithelium, then a stratified cylindrical epithelium without cilia,which gradually becomes cubical, and finally passes into a stratified. Fio. 217.—Longitudinal Section of a Cystic Polypus of the Tympanic Cavity,with papillary surface, x 12. (Alum cochineal.) o, Cysts. squamous epithelium. This, becoming considerably thickened in itslower layers, may assume the form of a rete Malpighii, sendinginto the substance of the polypi cones which readily undergo hornytransformation. In the tubular depressions, which have often beentaken for glands, the epithelium however remains mostly of thestratified cylindrical variety and is also provided with cilia. The surface of the polypi is smooth only in the rarest instances;usually it recalls the surface of a papilloma (Fig. 217), and the 432 THE EAR strangest forms may develop owing to the presence of deep indenta-tions, as well as to secondary and tertiary formation of lobule often grows to a smooth polypus of larger size and usuallyfibrous in structure, whilst the papillary excrescen
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpatholo, bookyear1895
