It is generally believed that cell elongation is regulated by cortical microtubules, which guide the movement of cellulose synthase complexes as they secrete cellulose microfibrils into the periplasmic space. Transversely oriented microtubules are predicted to direct the deposition of a parallel array of microfibrils, thus generating a mechanically anisotropic cell wall that will favor elongati...

In arthropods, the animal body is isolated from the external environment by a protective exoskeleton called the cuticle. The cuticle of young larvae has certainly been the most scrutinized structure in Drosophila and genetic studies of the pattern of cuticular extensions has provided the main source of our comprehension of the control of embryonic development. However, the complex structure of ...

Many investigators have reported on the fine structure of the boundary between dermis and epidermis, but their results were different from one another. Herxheimer (1916), working on the normal and abnormal human skin, pointed out that the cytoplasmic processes of the epithelial cell project toward the dermis and they are intimately associated with the translucent basement membrane which exists ...

The epidermis of skin and the oral mucosa are highly specialized stratified epithelia that function to protect the body from physical and chemical damage, infection, dehydration, and heat loss. To maintain this critical barrier, epithelial tissues undergo constant renewal and repair. Epithelial cells (keratinocytes) undergo a program of terminal differentiation, expressing a set of structural p...

langerhans cell histiocytosis (lch) is the most common type of childhood histiocytic disorder with an incidence of 0.2 to 1 per 100,000 children under the age of 15 years (1). the clinical picture of lch varies from single system (s-s)bone or skin disease to multi-system disease (m-s) (2). we report a neonate with disseminated papulonodular eruption containing mononuclear cd1a and s100 positive...

he external skin layer, called epidermis, is a dynamic system of continuously proliferating and differentiating activity. It mainly consists of keratinocytes, melanocytes and immunocompetent cells (Langerhans cells). Structure and metabolism of the epidermis have two essential functions: to protect the skin from external influences and to maintain the hydration and the osmotic balance of the in...

The skin has a pronounced ability to adapt physical changes in the environment by exhibiting plasticity at cellular level. Transient mechanical deformations applied are accommodated without permanent tissue structure. However, sustained stress induces long-lasting alterations skin, which mediated shifts keratinocyte activity. To elucidate mechanism of epidermal stem cell plasticity, we implemen...

The epidermis undergoes constant cellular renewal at the basal cell layer to replace the continual loss of cells by the stratum corneum. Leblond and Walker (1) reviewed studies on turnover timest of normal epidermis and found that they ranged from 13—100 days in different mammals. Recently, Rothberg, et at (2) determined the turnover time of human epidermis by measuring isotopically labeled str...

BACKGROUND This study determines the expression of P53 protein and the intensity of immunoreactivity in basal cell carcinoma in comparison with the adjacent nontumoral epidermis in sun-exposed areas of the head and neck regions. The mean age of immunoreactivity in tumoral and adjacent nontumoral epidermis is also determined. METHODS This descriptive-analytical study was performed retrospectiv...