Tympanic membrane retraction become eroded. As skin cells die they form a barrier of dry protein called keratin. This layer of keratin is normally pushed out of the ear by migration of skin cells along the ear canal and is turned into wax. Clearance of keratin can be disrupted by tympanic membrane retraction so that keratin accumulates within the retraction pocket. When keratin becomes trapped deep inside the ear and cannot be cleaned out, it is known as cholesteatoma. Growth of bacteria in the trapped keratin causes smelly discharge from the ear and can spread to cause serious infection. Various strategies may be
Plasma membrane transformation they do in rats and mice, after which they return (within the next 48 h) to form the interface of the mature placenta. Moreover, as we have also seen, there are molecular alterations in the plasma membrane during early pregnancy which have common aspects across species and here some of the large mucin molecules (such as MUC-1) are particularly instructive. Changes in the basal and lateral plasma membrane regions have also been documented in many species during early pregnancy in preparation for attachment, and these too show common aspects across species—especially some membrane junctional structures. Therefore, to highlight that membrane