238
However, in recent years promising studies have been done on yolk sac mesen-
chymal SC not only for human (Wang et al. 2008 ; Xiao-dong et al. 2003 , 2005 ) and
rodents (Favaron et al. 2014 ; Zhao et al. 2002 ; Zhao 2003 ), but also for other species
such as dog (Fratini et al. 2016 ; Wenceslau et al. 2011 ) and bovine (Mançanares
et al. 2015 ). The yolk sac membrane used for mesenchymal SC isolation usually
present a villous structure for which the histological microenvironment is composes
by endodermal cells, mesenchyme with vitelline vessels inside and a basal mesothe-
lium (Fernandes et al. 2012 ). The vitelline vessels are abundant inside the mesen-
chyme and the endodermal cells high proliferative during the gestation (Fig. 12.1a–c).
Using tissue explants or digestive solutions such as trypsin or collagenase, mesen-
chymal SC are isolated and available for culture (Fig. 12.1d). As the membrane, the
mesenchymal SC-derived from the yolk sac show interesting and promising charac-
teristics regarding to the morphology, growth and differentiation potential.
12.3 Amniotic Membrane and Derived Stem Cells
The amnion is the innermost membrane that surround the embryo/fetus during the
entire pregnancy. It forms a sac that contains the amniotic fluid (Favaron et al.
2015 ), a novel and interesting source of SC for cell therapy, especially due to their
Fig. 12.1 Yolk sac morphology and cell culture. (a) The yolk sac membrane is composed by endo-
dermic cells (E), mesenchyme (M) with vitelline vessels (V) and mesothium (Mes). Staining using
hematoxilin and eosin. (b, c) Immunohistochemistry for vimentin showing the intense vasculariza-
tion (V) of the yolk sac membrane and for PCNA, showing high proliferation of the endodermic
cells (arrows). (d) Culture of yolk sac stem cells from rodent (Necromys lasiurus, Cricetidae).
Note the yolk sac explant (Yst) with fibroblastic-like stem cells (arrows) with a central nucleus
P.O. Favaron and M.A. Miglino