Patterns of hypoglossal nucleus development in the prenatal period of human ontogenesis: a morphometric study

Better understanding the origin and differentiation of neurons in the medulla oblongata will promote comprehension of different neural systems functional importance, including the hypoglossal nucleus. There are a few studies addressing histostructure and morphometric parameters of hypoglossal nucleus in human embryos and fetuses in the scientific literature. Aim. To establish the structure, morphometric parameters of the hypoglossal nucleus and the nerve cells that go to form it in the embryos and human fetuses of different gestational age. Materials and Methods. A morphological and histological study of 230 human embryos and fetuses from 6-7 to 39-40 weeks of prenatal development was carried out. Results. In the prenatal development of the hypoglossal nucleus from 17-18 weeks of gestation neuroblasts are changed from spherical to oval shape, during the 20-21 weeks polygonal nerve cells are showing in nucleus composition, and polygonal nerve cells become dominated from the 37 week. The biggest area of the hypoglossal nucleus has been determined in human fetuses at gestational age of 39-40 weeks - 0.82 +/- 0.04 mm(2). The mean values of the nerve cells area are the largest in the 33-34 weeks gestational-age human fetuses - 301.2 +/- 9.3 mu m(2), and the mean values of the nerve cells nuclei are the largest in the 39-40 weeks gestational-age human fetuses - 101.2 +/- 3.2 mu m(2). Conclusions. The most intensive increase in the area of the hypoglossal nucleus identified in human fetuses at gestational age of 10-11 weeks - by 66.7 %, 12-13 weeks - by 45.4 %, 20-21 weeks - 31.2 %, 22-23 weeks - 36 %, 37-38 weeks - by 45.1 %, 39-40 weeks - by 42.7 % (p<0.01). Intensive increase in the mean neuroblasts area was detected in human fetuses at gestational age of 10-11 weeks - by 40.1 %, 17-18 weeks - 48.4 %, and decrease - in human fetuses at gestational age of 37-38 weeks - by 29.9 % (p<0.01). The most intensive increase in the mean area of neuroblasts was detected in human fetuses at gestational age of 14-15 weeks - by 43.4 % and 39-40 weeks - by 19.8 % (p<0.01).