Morphology of the cardiovascular system in greater rhea (Rhea americana americana Linnaeus, 1758)

Greater rheas have been the subject of scientific studies in the various areas of veterinary and biology in order to obtain essential information for their captivity management. The aim of this study was to describe the morphology of the greater rhea heart. The 20 animals were incised in sagittal plane, then fixed in 3.7% formaldehyde and dissected after 72 h. In addition, samples from the cardiovascular system were collected, processed for hematoxylin-eosin and Gomori Trichrome Staining. The heart is conical in shape, dark red when fresh and is located between the hepatic lobes. It has two atria and two ventricles, and four valves (left and right atrioventricular, aortic and pulmonary). The aorta and pulmonary trunk emerge at the heart base, while the ostia of the cranial and caudal vena cava emerged from the right atrium and the right and left pulmonary veins and the left coronary vein from the left atrium. From the aorta artery, the right and left coronary arteries arose, which originated, respectively, the superficial and conal branches and the profuse, left ventricular and superficial branches, being responsible for the irrigation of the heart. Microscopically the heart was constituted by simple pavement epithelium, rich in loose connective tissue. The aorta and pulmonary arteries were composed of the intima, middle and adventitial tunics. Thus, it is concluded that the morphological findings of greater rhea resemble those described for other birds such as ostrich and Gallus gallus domesticus.

Intussusception Associated with Sand Accumulation in a Greater Rhea (Rhea americana)

Pathoanatomical studies of diseases that affect wild animals are extremely important as appropriate measures can then be taken for the prevention and control of such diseases. We report here the case of death of a greater rhea (Rhea americana) by intestinal intussusception secondary to the ingestion of a large amount of sand. The animal was bred at the Center for Multiplication of Wild Animals of the Federal Rural University of the Semi-Arid. The animal died after presenting clinical signs of apathy, weakness, prostration, and inability to move, drink water, or eat. After death, the carcass was immediately sent for necropsy. During necropsy, intussusception was found involving the jejunum, ileum, and colon. The duodenum contained large amounts of coarse sand. The invaginated intestinal segments were reddish in color, with necrotic spots, and covered by a fibrinous exudate. Histopathological examination of the invaginated segments showed necrosis of the enterocytes, detachment of the intestinal epithelium, and the presence of inflammatory cells. The ingestion of a large amount of sand may have resulted in altered intestinal transit, contributing to the occurrence of intussusception, which resulted in ischemic alterations, intestinal necrosis, and consequent death of the animal.

Morphological aspects of epididymal microscopy and rete testis in greater Rhea Americana

ABSTRACT: The purpose of this research was to study the histology and describe the microscopy findings of the epididymis epithelium of greater Rhea americana at three time periods: November 2005 (n=14), December 2006 (n= 20), and May 2007 (n= 20), to observe and compare the differences that occurred. We studied the epididymis from 54 rheas, bred in Santa Maria, Rio Grande do Sul, Brazil. The epididymis were collected during commercial slaughter and fixed in bouin. Optical microscopy was used to measure the cellular structure, types of cells, tubules, and stereological values like the epididymis epithelium diameters, lumen, thickness, and relative volume of the tissue structure. Additionally, electron microscopy was studied. In December 2006 and May 2007, the means of the epididymis tubular diameter were: 79.1 and 58.1 µm, epithelium thickness: 24.0 and 52.2 µm, and lumen diameter: 55.0 and 5.8 µm, respectively. Regarding the volumetric proportion, we reported the following values: epithelium volume 36.2 and 80.4%, lumen without spermatozoon 19.6 and 3.0%, lumen with spermatozoon 5.4 and 0.0%, interstitium 35.4 and 12.0%, blood vessels 3.5 and 4.6%, structures in cellular superficies 1.4 and 0%, lamina 1.4 and 3.2%, and artifacts 0.3 and 1.3%, respectively. The epididymis ducts had a circular form in transverse sections with spermatozoon only in November 2005 and December 2006. The Rhea’s epididymis morphology was found to be similar to ostriches, roosters, and Japanese quail. Here, we present data from stereological microscopy (tubular diameter, epithelium thickness, and lumen diameter), volumetric proportion (epithelium, lumen without spermatozoon, lumen with spermatozoon, interstitium, blood vessels, structures in cellular superficies; cilium, estereocilium, and lamina) in this species during the repose and sexual activity period (reproductive season).

The number of pores per area of eggshells is not always a reliable indicator of Rheidae species

From the end of the Pleistocene and up until the late Holocene, bones and abun- dant eggshell fragments testify to the hunting by the indigenous people of Rheidae in the Pampas and Chaco regions (greater rhea, Rhea americana), and in the Argentinian Patagonia (lesser/ Darwin´s rhea, R.pennata). The traditional method to set apart eggshell fragments from these two species consisted in counting the number pores on a given area to estimate their density. In this paper we evaluate the validity of this method with a new protocol to facilitate counting and assess its reliability on a large eggshell sample. As has been repeatedly proved, the greater rhea has a larger pore density than the lesser rhea. However, the variability of this density within each species, and even within the same egg, needs to be considered as this may lead to erroneous identification. More so when the number of pores per cm2 falls in the lowest range of the greater rhea or the highest range of the lesser rhea. In general, it is easier to misidentify a greater rheaeggshell fragment for that of the lesser rhea than the other way around. The possibility of misidentification also depends on the area of the shell that is being analyzed, since the original method did not apparently assess the density of pores in different areas of the same egg for each species. Although our results indicate that identification based on the original method is not as reliable as the one we propose here, a reappraisal of it with larger samples deriving from a larger specter of populations from both species would be recommendable.