An electron microscopic study on the type I pneumocyte in the cat: differentiation

This investigation describes the differentiation of the type I pneumocyte from undifferentiated pulmonary epithelium. Cells lining subpleural alveolar septa were photographed from serial sections with the electron microscope and a three dimensional representation of each cell was obtained by transferring the contours of the cell membranes from micrographs to transparent plastic sheets which were then spaced to scale and stacked. The results of this study indicate that: (1) the only reliable criterion for differentiating between type I and type II cells is the commencement of attenuation of the type I cell; (2) differentiation of the type I cell occurs via the formation of one or more cytoplasmic attenuations that eventually fuse peripherally, thereby surrounding the unattenuated cell soma; (3) with respect to individual cells, blood-air barriers tend to form in distal areas of the attenuating cytoplasm before proximal areas; (4) both type I and type II pneumocytes retain certain characteristics that reveal their common origin.     

Emotional arousal and aggressive behavior

Reviews evidence that (a) supported the proposition that general emotional arousal facilitates aggression in the presence of aggressive cues and (b) substantiated the position that an arousal state of anger specifically increases the instigation to aggression. Furthermore, research is reviewed which supports the view that additional general arousal increases or decreases the effect of anger on aggression, depending on whether the arousal state is attributed to the source of the anger or to another source of general arousal. Controversy about the anger/aggression relation is discussed in terms of the failure to specify the function of the aggressive response. Research revealed that if the aggressive response is directed primarily toward injuring the target (but not toward some other goal), an angered person expresses aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)