Abstract: Objective To explore the role of microtubule-associated protein 2 (MAP-2) and nestin in the development of tongue
muscles of human embryos and fetuses. Methods PV immunohistochemistry was used to detect the expressions of MAP-2 and
nestin proteins in the tongue tissues of human embryos and fetuses at the second, third and fourth months of gestation.
Results MAP-2 and nestin positivity was detected in the tongue muscles of human embryos at 2 to 4 months of gestation. In
the embryos at the second month of gestation, no obvious MAP-2 positive cells were found in the tongue muscles; at 3 and 4
months, the number of MAP-2-positive cells in the tongue muscles was 24.14±8.28 and 15.86±3.89, with the expression intensity
of 109.42 ± 11.62 and 124.27 ± 8.73, respectively. At 2, 3 and 4 months of gestation, the number of nestin-positive cells in the
tongue muscles was 12.50±3.17, 19.00±7.63, and 22.80±6.91, with expression intensity of 119.99±24.02, 102.20±11.76, and 98.24±
10.66, respectively. As the gestational age increased, the number of MAP-2-positive cell number continued to decline following
a transient increase but the expression intensity kept increasing; nestin-positive cells increased continuously but the expression
intensity kept decreasing in the embryonic or fetal tongue muscles. Conclusion MAP-2 and nestin proteins are involved in the
regulation of the development of tongue muscles in human embryos and fetuses.