STRUCTURAL FEATURES OF THE HUMAN SPINAL GANGLION CAPSULE AT THE INTRAUTERINE STAGE OF DEVELOPMENT

Abstract

The paper presents the research data on the structural features of the human spinal ganglia capsule at 20-23 weeks of intrauterine development based on the investigated macro preparations, traditional histological preparations as well as semi-thin sections. The aim of research included the study of the structural organization of the human spinal ganglia capsule at the late stages of the intrauterine developmental period. The object of the study was spinal nodes (L2-L4) of 12 abortive fetuses obtained after the pregnancy termination at 20-23 weeks for medical and social indications. The sampling of the material was carried out according to the general methods accepted in the morphological studies. After the anatomical preparation, the spinal ganglia were fixed in 10% solution of neutral formalin, dehydrated in alcohol series and embedded in paraffin by the classical method. The serial sections 5-7 ?m thick were obtained from the paraffin-embedded blocks, which were stained with hematoxylin and eosin by Van Gieson method. After fixation in 4% solution of glutaraldehyde, the semi-thin sections were obtained applying the classical method and stained with toluidine blue. It was determined that the spinal dura mater passed directly to the spinal ganglion through the posterior root and then to the trunk of the corresponding spinal nerve. Thus, the spinal dura mater passing from the posterior root to the spinal ganglion directly participated in the formation of its capsule. Two layers with the marked morphological differences were determined in the spinal ganglion capsule. The thicker, outer layer that is the continuation of the spinal dura mater was represented by the connective tissue with a small number of collagen fibers and moderate amount of cellular elements. The cellular elements population was represented mainly by mature fibroblasts. The outer layer of the spinal ganglion capsule was also characterized by the presence of relatively large blood microvessels, mostly of the venous type, often with the marked hyperemic manifestations. The inner layer of the spinal ganglion capsule, compared to the outer one, at the studied stage of fetogenesis was characterized by the significantly dense localization of the fibrillar structures. Moreover, the greater number of the cellular elements was observed in the inner layer. The presence of the large number of blood vessels, which in comparison with the outer layer blood vessels, have the significantly smaller diameter, but greater density of localization, was the distinctive feature of the inner layer of the spinal ganglion capsule. The total thickness of the spinal ganglion capsule at the studied stage ranged from 32-42 ?m and averaged 35.8 4.2 ?m. Conclusions 1. The human spinal ganglion capsule at 20-23 weeks of the intrauterine development is completely formed and does not differ significantly from that in the postnatal period. 2. The spinal ganglion capsule at the studied stage of fetogenesis has two layers: the outer layer formed by the spinal dura mater which passes into the epineurium of the corresponding spinal nerve trunk and the inner one which continues into the perineurium of the corresponding spinal nerve. 3. The connective tissue capsule does not clearly separate the spinal ganglion interstitium from the endonevral space of the corresponding spinal nerve trunk and the anterior root of the spinal cord.

Keywords

• intrauterine period of development
• spinal ganglion
• nervous system