Histological studies on embryonic development of the rabbit heart.

Two experiments were performed to evaluate the normal development of the rabbit heart. In the first experiment the most intensive period of heart development was determined in rabbit embryos. The second experiment studied the most intensive period of heart development, determined in the first experiment, by concentrated sampling at 8-hour intervals. After cutting open the uterine wall opposite the discoid placenta, rabbit embryos were removed from the ampullae of the uterus using capillary tubes, under stereomicroscope at fivefold magnification. The embryos were subsequently placed into 4% formalin solution for 24 h. After fixation, slides stained with haematoxylin and eosin were made for histological examination. In the first experiment 51 embryos were examined, while during the second experiment a total of 113 embryos, representing different stages of development, were collected. Finally the data obtained on rabbits were compared with the well-known development of the heart in humans and mice.