[Pollen of gramineae and its botanical, taxonomical, and ecological aspects]. / Polen de gramíneas y sus aspectos botánicos, taxonómicos y ecológicos.

This is a review of tropical pollens (Gramineae) which cause allergy, addressed to medical workers and with emphasis in the Costa Rican. The graminean family Poaceae is widely distributed and has great genetic plasticity. An evolutionary tendency to floral reduction has led to anemophily, with pollens ranging from large (e.g. corn, Zea mays) to very small (e.g. tribes Poae and Avenae). This family produces a large number of pollens per panicle. The early morning production of free pollen (before 8 am) enhances allergic problems. In contrast, in rice (Oryza sativa) most pollen is liberated near mid day, which favours long range dispersal because of more appropriate environmental temperature and humidity. This can explain why rice is the first cause of allergic sensitivization in the asthmatic patients of the Costa Rican driest provinces (Guanacaste and Puntarenas). Despite the small size of several temperate and tropical species are present, because of geographic position, climatic diversity, irregular topography, etc. This paper presents a general description of the subfamilies Pooideae, Panicoideae, Chlorideae (Eragrostoideae) and Oryzoideae (including the medically most important tribes). Their pollens are illustrated with light and electron microscopy.

[Post mortem changes in the intestinal mucosa and lung tissue of Mus musculus, observed by scanning electron microscopy]. / Cambios post mortem en mucosa intestinal y tejido pulmonar de Mus musculus, observados al microscopio electrónico de barrido.

Post mortem ultrastructural alterations of surface epithelial tissues were studied by scanning electron microscopy. Ten male albino mice were sacrificed, and the duodenum, ileum and lung excised and fixed immediately, at 20, 40, 60 and 120 minutes post mortem. The intestinal villi and microvilli tended to flatten and to lose rigidity of cellular architecture. Alveolal epithelial cells showed the beginning of edema. Ultrastructural changes in epithelial cells were noticed as early as 20 minutes after death.