ABSTRACT
Serial sections of 4-5 mm. rabbit embryos were carefully studied in relation to the serial sections 10 mm pig embryos under a low-power microscope to compare the development of the branchial apparatus. Three pairs of the branchial arches can be clearly identified in 4-5 mm rabbit embryos. The first two are more prominent than the others. The aortic sac or the ventral aorta, the continuation of the truncus arteriosus, is located between the right and left hyoid arches. The thyroid diverticulum passess the aortic sac to attain its final position at the more caudal region. Each aortic arch branches from the aortic sac and passes through the mesenchyme of each branchial arch to join the dorsal aorta. The branchial apparatus of the 4-5 mm rabbit embryos is very similar to that of the 10 mm pig embryos. Since rabbit embryos are very to obtain for slide preparation, there is no significant problem in using rabbit embryos to study the development of the branchial apparatus instead of pig embryos.
ABSTRACT
The urogenital system develops from the intermediate mesoderm, the coelomic epithelium and the endoderm of the urogenital sinus. The urinary system of mammal is characterized by three sets of kindneys, i.e. the nonfunctional pronephros, the mesonephros and the functional metanephros. The metanephros or the permanent kidney develops from the ureteric bud and metanephrogenic tissue. At the beginning the kidney is located in the pelvic region but later gradually ascends to the abdomen. The urinary bladder development of human urinary system in the Department of Anatomy, Siriraj Hospital, we have employed serial sections of 10-15 mm pig embryos as laboratory models. This method of laboratory study is helpful in understanding and recognizing how the kidney forms. It is quite regrettable that nowadays the pig embryos are no longer available. Thus, it is necessary to find another suitable laboratory model and study the details of its normal kidney development. In this study, we demonstrated that 12-14 mm rabbit embryos can be used instead of pig embryos as the development of the metanephros is very similar. Although the rabbit’s mesonephros is smaller than that of the pig, it resembles the human mesonephros more closely. For this reason, the rabbit embryo is suitable for use as a laboratory model for embryology education of urinary system.
ABSTRACT
Serial sections of 4-14 mm rabbit embryos were carefully studied in relation to the serial section of 10 mm pig embryos under a light microscope in order to compare the development of the heart and related blood vessels. The heart of the 4-14 mm rabbit embryo has incompletely divided chambers comprising two atria and two ventricles. The partition of the atrium by the septum primum can be seen at the 4 mm stage and still incompletely attaches to the endocardial cushion even at the 12 mm stage. The rupture of the septum primum brings about the communication between the two atria, the foramen secundum, can be seen only at the 12 mm stage. Communication between the two ventricles is also via the interventricular foramen. The right atrium receives venous blood from the right horn of the sinus venosus which is larger than the left side. The bulbus cordis communication with the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the right ventricle and brings blood to the aortic sac which extends branches to the branchial arches to join the dorsal aorta. The heat of the rabbit embryo is very similar to that of the pigembryo. The pig embryos are easy to obtain for slide preparation, there will be no problem in using rabbit embryos for the study of the development of the heart.