Stereology of the myocardium in two species of Callithrix (Callitrichidae, primates)

Functional Cardiovascular Characterization of the Common Marmoset (Callithrix jacchus)

Appropriate cardiovascular animal models are urgently needed to investigate genetic, molecular, and therapeutic approaches, yet the translation of results from the currently used species is difficult due to their genetic distance as well as their anatomical or physiological differences. Animal species that are closer to the human situation might help to bridge this translational gap. The common marmoset (Callithrix jacchus) is an interesting candidate to investigate certain heart diseases and cardiovascular comorbidities, yet a basic functional characterization of its hemodynamic system is still missing. Therefore, cardiac functional analyses were performed by utilizing the invasive intracardiac pressure-volume loops (PV loop) system in seven animals, magnetic resonance imaging (MRI) in six animals, and echocardiography in five young adult male common marmosets. For a direct comparison between the three methods, only data from animals for which all three datasets could be acquired were selected. All three modalities were suitable for characterizing cardiac function, though with some systemic variations. In addition, vena cava occlusions were performed to investigate the load-independent parameters collected with the PV loop system, which allowed for a deeper analysis of the cardiac function and for a more sensitive detection of the alterations in a disease state, such as heart failure or certain cardiovascular comorbidities.

Stereology of the liver in three species of Leontopithecus (Lesson, 1840) Callitrichidae--primates

Studies on liver morphology and stereology are relevant to the comparative anatomical and pathological research. They also facilitate the use of non-human primates in basic research, which has substantially supported studies in human medicine. Quantitative studies of liver structures have also been more extensive in Old World primates and other vertebrates. Twenty-three livers of adult lion tamarins were studied (six Leontopithecus rosalia, seven Leontopithecus chrysomelas, and 10 Leontopithecus chrysopygus), dissected, and fixed in 10% neutral buffered formalin solution. For stereological quantification, the liver was regarded as consisting of parenchyma (hepatocytes) and stroma (non-hepatocytes). The volume density (V(v)) was determined by point counting, and the disector method was used to obtain the numerical density of hepatocytes (N(v)). Hepatic stereological differences among the three species of lion tamarins were not statistically significant. Therefore, the pooled V(v[hepatocyte]) and V(v[stroma]) could be determined as 96.2 and 7.4%, respectively, and N(v[hepatocyte]) as 500.33 x 10(6) cm(-3). Significantly different, the values found for V(v[hepatocyte]) and N(v[hepatocyte]) in lion tamarins were, respectively, 0.09 and 2.8 times greater than those in baboons, and 0.17 and 3.8 times greater than those in man. However, the V(v[stroma]) was 1.04 times smaller than that in baboons and 1.79 times smaller than that in man.

Stereological tools in biomedical research

Stereological studies are more and more frequent in literature, particularly in the development/evolution, pathology, and neurosciences areas. The stereology challenge is to understand the structural inner three-dimensional arrangement based on the analysis of the structure slices only showing two-dimensional information. Cavalieri and Scherle's methods to estimate volume, and Buffon's needle problem, are commented in the stereological context. A group of actions is needed to appropriately quantify morphological structures (unbiased and reproducibly), e.g. sampling, isotropic and uniform randomly sections (Delesse's principle), and updated stereological tools (disector, fractionator, nucleator, etc). Through the correct stereology use, a quantitative study with little effort could be performed: efficiency in stereology means a minimum slices sample counting (little work), low cost (slices preparation), but good accuracy. In the present text, a short review of the main stereological tools is done as a background basis to non-expert scientists.

Stereology of the myocardium in Leontopithecus (Lesson, 1840) callitrichidae - primates

Rare morphological features of the Leontopithecus cardiovascular system have been reported in the literature. The samples analyzed in this study came from 33 specimens of Leontopithecus from the collection of the Center of Primatology of Rio de Janeiro-FEEMA (CPRJ-FEEMA). Morphometry and stereological data were obtained from all animals. Adult body weights of L. rosalia were the lowest, the greatest being those of L. chrysopygus caissara; body weights of L. chrysomelas and L. c. chrysopygus were similar and in between those of the two former species. Cardiomyocytes (left ventricular myocardium) were bigger in adults than in infants. The myocardium of L. rosalia showed focal fibrosis, fatty vacuoles, and hyalinization. In L. chrysomelas the myocardium showed areas of fibrosis and presence of mononuclear cells. Fibrosis and areas of congestion were observed in L. c. chrysopygus; areas of disorganization and vascular congestion were found in L. c. caissara. In L. rosalia infants, a greater density of vessels per myocardial area and a greater length density of vessels were observed as compared with those of L. chrysomelas. In adults, L. chrysomelas showed greater density of connective tissue in the myocardium than L. c. chrysopygus and L. c. caissara did. In L. rosalia, cardiomyocyte nuclei had a greater area density than those of the other forms of Leontopithecus. These characteristics may explain the faster development of L. rosalia infants as compared with that of L. chrysomelas and L. c. chrysopygus kept under the same handling conditions at the CPRJ-FEEMA.