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Marcela S.G.,Laboratory Of Investigacion En Biologia Del Desarrollo Y Teratogenesis Experimental | Marcela S.G.,Laboratorio Of Citologia | Cristina R.M.M.,Centro Medico Nacional Siglo XXI | Angel P.G.M.,Colegio de Mexico | And 6 more authors.
Anatomical Record | Year: 2012

Adult and embryonic laboratory rats have been used as a mammalian model organism in biomedical research, descriptive and experimental cardiac embryology, and experimental teratology. There have been, however, considerable variations and discrepancies concerning the developmental staging of the rat embryo in the reported literature, which have resulted in several controversies and inconsistencies. Therefore, we carried out a careful anatomical and histological study of rat cardiac morphogenesis from the premorphogenetic period to the mature heart in a newborn pup. A correlation between the chronology and morphological features of the heart and embryo or newborn was made. We provide a simple and comprehensive guide relating the developmental timing and fate of the embryonic components of the heart and their morphological changes in the rat based on in vivo labeling studies in the chick. We also compare the timing of heart development in rats, humans, and mice. © 2012 Wiley Periodicals, Inc. Source

Guzman L.V.,Laboratory Of Investigacion En Biologia Del Desarrollo Y Teratogenesis Experimental | Mayoral P.V.,Hospital Infantil de Mexico Federico Gomez | Valencia J.P.,Hospital Infantil de Mexico Federico Gomez | Pine S.S.,Hospital Infantil de Mexico Federico Gomez | Gomez C.S.,Laboratory Of Investigacion En Biologia Del Desarrollo Y Teratogenesis Experimental
Anatomical Record | Year: 2010

No consensus exists regarding the precise contribution of myocardium and the atrioventricular (AV) cushion mesenchyme to the development of leaflets, tendinous cords (TCs) and papillary muscles. Furthermore, the origin and fate of the myocardium embedded in the immature mesenchyme of the AV cushions at the beginning of AV valvulogenesis is controversial. Some authors have suggested that these cells result from a mesenchyme-to-myocardium transformation. In contrast, other researchers have concluded that they are derived from the myocardial ventricular wall and the interventricular septum (IVS). On the other hand, it has been assumed that the AV mural and septal leaflets have the same pattern of development. However the supporting structures of the two types of leaflets are anatomically different, which could reflect some differences in the pattern of development. We have therefore investigated the morphogenetic processes involved in sculpting and maturation of the right septal leaflet (RSL) and TCs in embryonic and post-hatching chicken hearts. The origin and fate of the myocardium embedded in the immature cushion mesenchyme at the beginning of RSL morphogenesis was also studied. For this purpose, scanning electron microscopic analysis, histological studies and immunohistochemical detection of Nkx2.5 and MEF2C were performed. Our findings indicate that the RSL and TCs present a distinct morphogenetic pattern from that of the mural leaflets. Our results also provide evidence that myocardial recruitment from the IVS, but not mesenchyme-to-myocardium transformation, participates in the development of the muscular region of the TCs adjacent to the IVS. © 2009 Wiley-Liss, Inc. Source

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