Biomedical subjects

E B Casanave

Publications and source records attributed to E B Casanave.

9 recordsLinked to original sources

PubMed2003

The spleen of Zaedyus pichiy, (Mammalia, Dasypodidae): a light and electron microscopic study.

Armadillos are ancient mammals important as models for biomedical, evolutive and ecological studies, because they have adaptive and primitive morpho-physiological characteristics. In this work we study the splenic microarchitecture of the 'Patagonian Piche', Zaedyus pichiy, as an attempt to understand the relationship between the organizational plan of the organ and the particular features of this species. The organ samples were classically processed for light and electron microscopic study. The microanatomy of the organ as well as its different cell types are studied. The spleen is non-sinusoidal, with the typical arrangement for storage functions. White pulp is well defined. Red pulp is a meshwork of circulating, immunocompetent and haemopoietic cells. The general structure of the organ agrees with the semi-fossorial habit and the adaptability of the species. Comparative aspects with other armadillos or other less specialized groups are discussed. Persistence of haemopoietic spleen activity in the adult suggests the existence of specific inductive functions of the stroma. Better knowledge of spleen structure and function in ancient mammals may give important information about their phylogeny.

Animals↗

PubMed2002

Ultrastructure and morphometry of ovarian follicles in the armadillo Chaetophractus villosus (Mammalia, Dasypodidae).

Ultrastructural and morphometric changes in oocyte and surrounding granulosa cells during armadillo follicular growth are described. Primordial, intermediary, early and late primary, secondary, tertiary and preovulatory Graafian follicles were found. From primordial to Graafian follicle, granulosa cells increase in height, become multilayered while fluid-filled spaces arise among them in the tertiary follicle stage. As the follicle expands the oocyte is located eccentrically and grows in size. From primordial to secondary stage organelles develop in number and complexity and many vesicles start arising in the cytoplasm at the secondary stage. From tertiary follicle stage the number of mitochondria decreases. In follicular cells, secreting-related organelles expand, but mitochondrial number decreases according to the follicle expansion. Intercellular junctions between both cell types increase. The morphometrical study shows a biphasic pattern of oocyte and follicle growth. The morphological baseline here provided will be essential for further comprehension of the reproductive biology in armadillos.

Animals↗

PubMed2000

Spleen of Dasypus hybridus (Mammalia, dasypodidae): a light and electron microscopic study.

Armadillos are relictual mammals important as models for biomedical studies. They contain adaptative and primitive characteristics in both anatomical and physiological aspects. In this study we describe the splenic histology and cytology of the "mulita," Dasypus hybridus. Organ samples were processed for light and electron microscopy study. The microanatomy of the organ samples as well as their different cell types are described. The spleen is non-sinusoidal, with the typical arrangement for storage functions. White pulp is lightly diffuse. Red pulp is a meshwork of circulating, immunocompetent and hemopoietic cells. Differences with other studied members of the group are discussed. The general structure of the organ agrees with the semi-fossorial habit of the species. Persistence of myeloid activity in the adult suggests the existence of specific inductive functions of the stroma. Better knowledge of this fact may give further insight on the phylogeny of hemopoiesis.

Age Factors↗

PubMed1995

Decrease of body temperature in armadillos experimentally covered by soil.

The armadillo Chaetophractus villosus does not stop breathing when experimentally covered with soil. Under that condition, there is a gradual but considerable drop in deep rectal temperature (TB): after 90 minutes, mean +/- SD = 1.7 +/- 0.4 degrees C (n = 8). As soon as the soil is removed and the animal breathes open air, TB gradually increases.

Adaptation, Physiological↗

PubMed1995

Bradycardia in armadillos experimentally covered with soil.

Chaetophractus villosus is able to maintain efficient respiratory movements when its nostrils are experimentally covered with soil. Under these conditions, a progressive bradycardia develops. It would depend on hypothermia and asphyxia.

Adaptation, Physiological↗

PubMed1987

On the presence of a peculiar alpha rhythm in the olfactory tubercle of waking armadillos.

A very regular 8-12 rhythm was found in the olfactory tubercle of the armadillo Chaetophractus villosus. The rhythm was observed during wakefulness. Considerable sinusoidal activity was also observed not only during wakefulness, but during synchronized (slow) and desynchronized (paradoxical) sleep. The significance of this novel rhythm is discussed together with considerations that establish an important difference between it and the other 'alpha rhythms' known.

Alpha Rhythm↗

PubMed1987

Absence of apnea in armadillos covered by soil.

The armadillo Chaetophractus villosus shows a remarkable respiratory adaptation when the nostrils are completely covered by soil: it is able to maintain efficient respiratory movements with the corresponding filling of the lungs, thanks to a mechanism that allows it to use the air filling the space between the soil particles, without invasion of the nasal cavities by those particles.

Anesthesia↗

PubMed1986

Neocortical and olfactory bulb activity, in armadillos submitted to covering with soil.

Armadillos were submitted to an experimental condition in which their head and thorax were covered by a layer of soil 30 cm high. In this condition the electrical activity of the neocortex and of the olfactory bulbs was studied. Neocortical activity did not show signs of damage remaining without gross changes before, during and after the covering with soil. The olfactory bulbs showed a great decrease of bursting sinusoidal activity which almost instantaneously reversed when the soil was removed. The mechanisms of these changes are discussed.

Animals↗

PubMedDate not supplied

Body temperature of the armadillo Chaetophractus villosus (mammalia, dasypodidae).

Body temperature of the armadillo Chaetophractus villosus (n = 17) was studied during a period of 15 days. Deep rectal temperature (TB) was recorded at 9 am, 1 pm and 5 pm. Temperature in the laboratory was kept between 24.6 degrees C and 26.0 degrees C. We found two main different profiles of thermal behaviour in our animals, namely: a) one with high variation, mainly due to the daily cycle. b) the other with middle or low variation, with no predominance of the daily cycle. There were great TB differences between hours (P < 0.01). Morning temperatures were lower than the other ones. This is what could be expected in a non diurnal animal like C. villosus.

Animals↗