Abstract
The differentiation of the bulbar region and arterial outflow tract of the developing mouse heart was investigated by analysing serial transverse sections through the heart region of mouse embryos isolated between the eleventh and fifteenth day of gestation. Over this period of time, we observed the configurational and cellular changes occurring within the wall of this region of the heart, being particularly interested in the histological appearance of the cellular constituents of the spiral ridges and their eventual apposition and fusion to form the spiral septum. We observed that the mesenchyme cells of which the ridges are largely composed are initially orientated in the direction of the outflow tract, but subsequently realign themselves when the individual ridges become oblique and spiral in their configuration. The tissue that gives rise to the spiral septum, namely the 'bulbar cushions' proximally, and the 'truncal cushions' in the rest of the outflow tract appear at all stages to be continuous structures. We saw no evidence that they initially develop as separate entities, and subsequently fuse. Furthermore, no evidence of cell death was observed in either the mesenchyme tissue or in the wall of the outflow tract. We have therefore suggested that, contrary to the findings of Pexieder (1978), pre-programmed cell death probably plays no significant part in the development of the spiral septum in the mouse, though we cannot exclude the possibility that there may be species differences between the events associated with spiral septum formation in avian and mammalian embryos. We conclude from our histological observations that the changes that occur in the arterial outflow tract in the mouse are probably brought about by the haemodynamic effect of the forces of blood flow impinging on its walls and that this initiates a series of events that are controlled to a considerable degree by pre-programmed genetic instruction.
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- Anderson R. H., Wilkinson J. L., Becker A. E. The bulbus cordis--a misunderstood region of the developing human heart: its significance to the classification of congenital cardiac malformations. Birth Defects Orig Artic Ser. 1978;14(7):1–28. [PubMed] [Google Scholar]
- Frazer J. E. The Formation of the Pars Membranacea Septi. J Anat. 1916 Oct;51(Pt 1):19–29. [PMC free article] [PubMed] [Google Scholar]
- JAFFEE O. C. BLOODSTREAMS AND THE FORMATION OF THE INTERATRIAL SEPTUM IN THE ANURAN HEART. Anat Rec. 1963 Nov;147:355–357. doi: 10.1002/ar.1091470306. [DOI] [PubMed] [Google Scholar]
- Jaffee D. C. Hemodynamics and cardiogenesis: the effects of physiologic factors on cardiac development. Birth Defects Orig Artic Ser. 1978;14(7):393–404. [PubMed] [Google Scholar]
- Jaffee O. C. The development of the arterial outflow tract in the chick embryo heart. Anat Rec. 1967 May;158(1):35–42. doi: 10.1002/ar.1091580105. [DOI] [PubMed] [Google Scholar]
- Kaufman M. H., Navaratnam V. Early differentiation of the heart in mouse embryos. J Anat. 1981 Sep;133(Pt 2):235–246. [PMC free article] [PubMed] [Google Scholar]
- Kaufman M. H. The role of embryology in teratological research, with particular reference to the development of the neural tube and heart. J Reprod Fertil. 1981 Jul;62(2):607–623. doi: 10.1530/jrf.0.0620607. [DOI] [PubMed] [Google Scholar]
- Lomonico M. P., Moore G. W., Hutchins G. M. Rotation of the junction of the outflow tract and great arteries in the embryonic human heart. Anat Rec. 1986 Dec;216(4):544–549. doi: 10.1002/ar.1092160412. [DOI] [PubMed] [Google Scholar]
- Los J. A. Cardiac septation and development of the aorta, pulmonary trunk, and pulmonary veins: previous work in the light of recent observations. Birth Defects Orig Artic Ser. 1978;14(7):109–138. [PubMed] [Google Scholar]
- Mcbride R. E., Moore G. W., Hutchins G. M. Development of the outflow tract and closure of the interventricular septum in the normal human heart. Am J Anat. 1981 Mar;160(3):309–331. doi: 10.1002/aja.1001600308. [DOI] [PubMed] [Google Scholar]
- Navaratnam V., Kaufman M. H., Skepper J. N., Barton S., Guttridge K. M. Differentiation of the myocardial rudiment of mouse embryos: an ultrastructural study including freeze-fracture replication. J Anat. 1986 Jun;146:65–85. [PMC free article] [PubMed] [Google Scholar]
- Pexieder T. Development of the outflow tract of the embryonic heart. Birth Defects Orig Artic Ser. 1978;14(7):29–68. [PubMed] [Google Scholar]
- Rychter Z., Lemez L. Development of hereditary ventricular septal defects in Siller's strain of chick embryos. Birth Defects Orig Artic Ser. 1978;14(7):377–386. [PubMed] [Google Scholar]
- Sissman N. J. Developmental landmarks in cardiac morphogenesis: comparative chronology. Am J Cardiol. 1970 Feb;25(2):141–148. doi: 10.1016/0002-9149(70)90575-8. [DOI] [PubMed] [Google Scholar]
- Teal S. I., Moore G. W., Hutchins G. M. Development of aortic and mitral valve continuity in the human embryonic heart. Am J Anat. 1986 Aug;176(4):447–460. doi: 10.1002/aja.1001760407. [DOI] [PubMed] [Google Scholar]
- VANMIEROP L. H., ALLEY R. D., KAUSEL H. W., STRANAHAN A. PATHOGENESIS OF TRANSPOSITION COMPLEXES. I. EMBRYOLOGY OF THE VENTRICLES AND GREAT ARTERIES. Am J Cardiol. 1963 Aug;12:216–225. doi: 10.1016/0002-9149(63)90311-4. [DOI] [PubMed] [Google Scholar]
- Virágh S., Challice C. E. Origin and differentiation of cardiac muscle cells in the mouse. J Ultrastruct Res. 1973 Jan;42(1):1–24. doi: 10.1016/s0022-5320(73)80002-4. [DOI] [PubMed] [Google Scholar]
- de la Cruz M. V., Sánchez Gómez C., Arteaga M. M., Argüello C. Experimental study of the development of the truncus and the conus in the chick embryo. J Anat. 1977 Jul;123(Pt 3):661–686. [PMC free article] [PubMed] [Google Scholar]