Abstract-Studies have shown that the proximal coronary artery (PCA) develops via endothelial ingrowth from the peritruncal ring (PR) of the coronary vasculature. However, the details of PCA formation remain unclear. We examined the development of PCAs in quail embryonic hearts from 5 to 9 days of incubation (embryonic day [ED]) using double-immunostaining for QH1 (quail endothelial marker) and smooth muscle ␣-actin. At 6 to 7 ED, several QH1-positive endothelial strands from the PR penetrated the facing sinuses, and in some embryos, several endothelial strands penetrated the posterior (noncoronary) sinus. At 7 to 8 ED, the endothelial strands penetrating the facing sinuses seemed to fuse, forming a proximal coronary stem that was demarcated from the aortic wall by the nascent smooth muscle layer of the coronary artery. By 9 ED, two coronary stems were completely formed, and the endothelial strands previously penetrating the noncoronary sinus had disappeared. Confocal microscopy at 6 ED revealed discontinuous QH1-positive endothelial progenitors in the aortic wall at sites where the endothelial strands would later develop.Observations demonstrate that during the formation of the PCA, endothelial strands from the PR penetrate the facing sinuses and then fuse, whereas those strands penetrating the noncoronary sinus disappear. Thereafter, the coronary artery tunica media demarcates the definitive PCA from the aortic media. Key Words: coronary artery Ⅲ development Ⅲ quail embryo Ⅲ QH1 D uring early heart development, a coronary circulation is absent, because the cardiomyocytes are in direct contact with the endocardium. 1 After the formation of the d-loop heart (stage 14 to 15 in chick embryo, 2 2.5 embryonic day [ED]), the proepicardial organ develops from the dorsal mesocardium of the sinus venosus, migrates onto the surface of the cardiac tube, and gives rise to the primitive epicardium. 3,4 After the formation of the epicardial covering of the heart, vascular buds or blood island-like structures, which arise in the epicardium, form in various species, including birds. 5,6 In chick embryo, endothelially lined vascular anlagen appear in the epicardium at approximately stage 21 (3.5 ED). 4 Coronary vascularization begins to occur at stage 32 (7.5 ED), first as venous sinusoids in connection with trabecular channels and second as coronary arterial vessels anastomosing with the venous sinusoids. 7 Then a closed coronary system is completed by stage 41 (15 ED). 7 Recent experiments with chick-quail chimeras and retroviral tracers have shown that not only coronary vessel endothelial cells but also smooth muscle cells originate from the epicardium. 8 -10 Retroviral-tracer experiments have also made clear that the cells making up the coronary vessels originate from discontinuous colonies, suggesting that coronary vessels are established by vasculogenesis rather than by angiogenesis. 8 Several investigators have examined the origin of the proximal coronary artery stems and coronary orifices. A process often assumed to be...

NKT cells are relatively resistant to radiation and might therefore be suitable for adjuvant immunotherapy to eradicate remnant cancer cells in patients who have undergone radiation therapy.

No abstract

SynopsisSpontaneous ovulation was inhibited in female rats with isocarboxazid (IC), MAO-Inhibitor. Administration of HCG to IC-treated females at 3:00p.m. on the day of proestrus induced ovulation. Although the brain serotonin level was still high (1.5 times the control) from 9:00a m. to 6:00p.m. on the next day after IC-injection, ovulation occurred on the second day morning. Female rats, with the increased brain serotonin level by IC-injection, copulated on the afternoon of proestrus, and ovulation occurred in the mated animals on the next morning. These results indicate that the stimulus provided by mating may overcome the inhibitory effects of serotonin in IC-treated females.