Rigoglio NN, Matias GDSS, Miglino MA, Mess AM, Jacob JCF, Smith LC. Morphological characteristics of mule conceptuses during early development.
Anim Reprod 2018;
15:1214-1222. [PMID:
34221135 PMCID:
PMC8203116 DOI:
10.21451/1984-3143-ar2017-0035]
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Abstract
Hybrids between species are often infertile and extremely rare among mammals. Mules, i.e.
crossing between the horse and the donkey, on the other hand are very common in agricultural
and leisure practices due to their enhanced post-natal physical characteristics that is
believed to occur for outbreeding or hybrid vigor. Since no reports are availableon the effects
of hybrid vigor during early development, this study focused on characterizing the intrauterine
development of mule conceptuses during critical embryo-to-fetus transition period. Nine
embryos and fetuses of early gestation, obtained after artificial insemination and transcervical
flushing, were evaluated by means of gross anatomy and histology and compared to data available
for the equine. We found that some events, such as C-shape turning, apearence of branchial
archs, limb and tail buds, formation of primary and secondary brain vesicles, heart compartmentalization,
and development of somites, occurred slightly earlier in the mule. Nonetheless, no major
differences were observed in other developmental features, suggesting similarities between
the mule and the horse development. In conclusion, these data suggest that the effect of hybrid
vigor is present during intrauterine development in the mule, at least with regard to its maternal
parent.
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