Morphological and immunohistochemical characteristics of human trigeminal ganglion neurons in the prenatal period of development

Introduction: Data related to the amount, size and morphological characteristics of cell elements of sensory ganglia at different stages of prenatal development has not been fully elucidated in recent scientific publications. At the same time publications considering the study of cell structure of trigeminal ganglion in the postnatal period confirm heterogeneity of its neurons. The aim of the research was to study morphological and immunohistochemical characteristics of human trigeminal ganglion neurons at 12-14 weeks of prenatal development. Material and Methods: The study was made on 24 trigeminal ganglions of 12 human fetuses at 12 to 14 weeks of prenatal development after abortion made on social and medical indications. Results: At the studied period of the intrauterine development nerve cells of the trigeminal ganglion significantly differed in size, tinctorial properties and degree of argentophility of the perikaryon. At the same time, the number of small nerve cells with an average diameter of less than 15 pm prevailed. Immunohistochemical study allowed detecting the apparent Bd-2 expression in the overwhelming number of small neurons; the expression of this marker has been observed in 50% of cells of the medium-sized neurons. No Bd-2 expression has been found in most of the large neurons. Almost all the neurons, regardless of the size, showed moderate Ki-67 expression, protein S-100. VEGF expression has also occurred in the vast majority of the nerve cells of all size groups. Conclusions: 1. Human trigeminal ganglion neurons both at 12-14 weeks of prenatal development and in postnatal period are represented by heterogeneous population. 2. Polymorphism of trigeminal ganglion neurons has been found by all applied techniques. 3. Detected polymorphism is the evidence of processes of maturation and differentiation of neurons in human trigeminal ganglion at 12-14 weeks of prenatal developmen