Development of dromedary camel heart

Atrioventricular node (AVN) and Atrioventricular bundle (AVB) development in the camel heart was studied during the 1 st , 2 nd and 3 rd trimesters of gestation using histological techniques. Thirty hearts of camel foetuses were used in this study. Specimens were collected from Tamboul and Al-Salam slaughterhouses, Sudan. The samples were prepared by routine histological procedures and stained by the general histological stain (H&E) and some other special stains. AVN was found close to the atrioventricular opening in the 1 st trimester and close to the opening of the coronary sinus in the 2 nd and 3 rd trimesters. It generally appeared as a group of large-sized and lightly stained cardiac muscle cells. AVB was embedded in myocardium in the 2 nd trimester as a bundle of lightly stained fibres either located between the endocardium and myocardium or within the myocardium; in the early stages of the 3 trimester they appeared as groups of fibres which were covered by connective tissue between the endocardium and myocardium. It was concluded that the AVN and AVB showed very important histological developmental changes throughout the 3 gestational stages. Key words: Atrioventricular bundle, atrioventricular node, camel, foetus, histology rd

ABTRACT. Ultrastructure of the dromedary camel heart was studied during the second and third trimesters of gestation (131-426 days). A total of 10 hearts were used to study the ultrastructural development in camel foetuses. Hearts were collected from Tamboul slaughterhouse, Gezira, Sudan, and then they routinely prepared for scanning and transmission electron microscopy. The longitudinal groove started gradually as a shallow groove but the coronary groove was not observed till the last stage of first trimester of gestation. At the second and third trimesters, the atrial pectinate muscles showed gradual development and appeared as large branching and anastomosing plexiform cords. Pectinate muscles were thicker in the second trimester than in the third trimester. Whereas Z lines with irregular striations were present in the second trimester, there were no intercalated discs in the same trimester; they latter first appeared in the third trimester. Mitochondria were numerous around the myocytes nuclei and between the fibrils. The sarcomere in the third trimester was thicker than in the second trimester. The length and width of mitochondria in the second and third trimester were constant. It was concluded that organelles development started clearly in the second trimester and continued in the third trimester. Moreover, the atrial and ventricular myocardium showed obvious developmental changes during the second and third trimesters, especially in the transverse tubular system. Keywords: Dromedary camel, Foetal heart, Ultrastructure

The histological structure of the sinoatrial node (SAN) in the dromedary camel foetus was investigated using routine histological techniques and some special stains. Twenty foetuses were used. They were divided into two groups 10 foetuses were in the second trimester (131-260 days); the rest in the third trimester (261-423.5 days of gestation). Samples were collected from the right atrium cranial to the opening of cranial vena cava. The SAN in the camel foetus was found in subepicardial region cranial to the opening of cranial vena cava at the junction between the cranial vena cava and right atrium. Two types of cells were observed; the first type had dark cytoplasm and large spherical lightly stained nucleus. The cells of the second type were small and spindle in shape with dark small nuclei. It is concluded that SAN in camel foetuses in the second and third trimesters had the same location as in the adult and also had two types of cells as in other animal species.

Abstract Ultrastructural development of the camel heart was studied during the first trimester of gestation using transmission and scanning electron microscopy. Eight foetal hearts from the early and late stages of the first trimester (between 86 days and 128 days gestation) were collected and routinely prepared for electron microscopy. Scanning electron microscopy (SEM) results showed that during the early stages of the firs t trimester the heart of camel foetus was semi - triangular in shape. Both the coronary and longitudinal grooves were not clear . The atria were not clear at 84 days of gestation , and they appeared as small buds at 91 days of gestation. The pectinate muscles were also not well developed , and the heart was only in the form of two ventricles separated by longitudinal grooves during that stage. During the intermediate stages of the first trimester the longitudinal grooves and branches of the coronary arteries wer e clearly observed. The coronary groove was not observed until the end of the first trimester. Type II myocardial bridges were observed in this stage. Transmission electron microscopy (TEM) at (101 – 115 days) showed cardiomyofibres striations as irregular Z lines. Cardiomyofibres showed numerous mitochondria of different sizes and shapes around the nucleus and between fibrils. Rough endoplasmic reticulum was observed in the cytoplasm of cardiomyofibres in the form of few cisternae. It was concluded that th e development of the heart of camel foetus was not fully complete during the first trimester of gestation. Keywords: scanning electron microscopy, transmission electron microscopy, camel, foetus, hear