Embryonic origin of the caudal mesenteric artery in the mouse

It is commonly held that the caudal mesenteric artery (CaMA, or inferior mesenteric artery in humans) arises in the same manner as the celiac and cranial mesenteric artery (CrMA, or superior mesenteric artery in humans), i.e., from the remodeling of the vitelline system of arteries that surrounds and supports the yolk sac. Conflicting evidence about the precise manner in which the CaMA arises was presented in studies of the luxate syndrome (Carter: J. Genet. 1954;52:1–35) and sirenomelia (Schreiner and Hoornbeek: J. Morphol. 1973;141:345–358) in the mouse. These studies suggested that the CaMA arises from the remodeling of the medial umbilical arterial roots. Later studies of blood vessel development in the hindlimb of the Dominant hemimelic mouse (Gest: Anat. Rec. 1984;208:296; Anat. Rec. 1987;218:49A; Gest and Roden: Anat. Rec. 1988;220:37–38A) also supported the results of the previous studies. The present investigation tests the hypothesis that the CaMA arises as a result of the regression and remodeling of the medial umbilical arterial roots. Vascular corrosion casts of 9.5-13.5-day-old mouse embryos were observed by scanning electron microscopy (SEM). The results of the present investigation agree with the aforementioned studies. The medial umbilical roots initially conduct the blood to the placenta. On days 10-12 the medial umbilical roots regress and remodel into the CaMA, while the lateral umbilical roots take over the blood supply to the placenta. On the basis of our results, we conclude that the CaMA arises from the medial umbilical roots and not from the remodeling of the vitelline system of arteries, as previously assumed. Anat Rec Part A 271A:192–201, 2003. © 2003 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34292/1/10022_ftp.pd

A comparison of morphogenesis of muscles of the forearm and hand during ontogenesis and regeneration in the axolotl ( Ambystoma mexicanum )

The morphogenesis of muscles of the forearm and hand was studied in embryonic limbs of the axolotl ( Ambystoma mexicanum ) and compared with the course of morphogenesis in the regenerating limb of adults. The first part of the paper describes the morphogenesis of muscles ontogenetic development. The course of development, from the stage of muscle blastemas through that of the independent muscle anlagen is described for each muscle. The separation of muscle anlagen and their differentiation forms a prominent proximodistal gradient. At the same time there is a clear radioulnar gradient in the formation of muscle anlagen. Phylogenetically, this radioulnar gradient is restricted to the developing limb of Urodeles. In the second part of the paper, the morphogenesis of muscles is described in the regenerating limb. The major features in regeneration recapitulate those in the embryonic limb. Proximodistal and radioulnar gradients of development are also present in the regenerating limb. This structural similarity in development supports the viewpoint that the regeneration blastema is an integrated morphogenetic unit in which muscles differentiate according to the same genetic plan as they do in the embryo. There are some differences, however, between the regenerating and embryonic limb. The regenerating limb is larger, its muscle blastemas are also larger from the beginning, and the regenerating limb has a relatively greater amount of mesenchymal cells, which are not closely integrated into the muscle or skeletal anlagen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47521/1/429_2004_Article_BF00519726.pd

Untersuchung von Ein-Nukleon-Transferreaktionen mit polarisierten Deuteronen von 20 MeV

SIGLEDEGerman