Study On Morphological Structure Development And Three-dimensional Reconstruction Model Of Embryonic Midbrain

Midbrain is one of the important constitutes of human central nervous system.Damage in the midbrain can cause neurobehavioral diseases such as Parkinson's syndrome,schizophrenia,and hyperkinetic syndrome of childhood.In the midbrain,the red nucleus,substantia nigra,and ventral tegmental area function in the movement and control of the body,and the periaqueductal gray is related to the pain mechanism.Nowadays,the morphologic characteristics of important regions in the midbrain after birth have been explored by predecessors through slicing techniques and computer techniques.Little is known about the development of an overall morphological structure of the embryonic midbrain and the morphological development of internal interconnected structures.Serial sections of ICR mice midbrain from E14,E16 and E18 embryos and the midbrain of adult mice were prepared as starting material.The main three parts we done including:(1)Examination of the overall structure and cytoarchitecture of various area,including periaqueductal gray,red nucleus,substantia nigra,and ventral tegmental area;(2)Reconstruction of the three-dimensional model of the midbrain,and the aqueduct,red nucleus,substantia nigra,and ventral tegmental area in midbrain using continuous serial sections of mice midbrain.The morphological parameters were also measured;(3)Preparation of decellularized scaffold of midbrain and determination of its physical parameters.Details of each part are as follows:(1)The overall development of embryonic midbrain from E14-E18.At E14,the red nucleus,substantia nigra,ventral tegmental area,and periaqueductal gray have been formed.To E16,the morphological features are as follows,periaqueductal gray is differentiated into four sub-regions.The red nucleus elongates along the two sides of midbrain.The substantia nigra is further differentiated to form the substantia nigra compacta and substantia nigra reticulate.The ventral tegmental area moves downwards slowly and expanded to both sides of midbrain at the bottom area.It joins together with substantia nigra.To E18,each area was further differentiated and developed,the red nucleus grows further.the substantia nigra expands and is now separated from the ventral tegmental area.The ventral tegmental area moves downward further and grows to both sides at the bottom of the midbrain.(2)Reconstruction of the 3D model of several nuclei at each development stage,and measurement of their corresponding parameters.The shape of the midbrain at E14 is nearly conica.To E16,the midbrain continues to expand based on its original form,and the volume increases by 118.7%.To E18,the midbrain is further enlarged,and the volume is41.4% larger than that of E16.For aqueduct,the volume of the central aqueduct is larger in E14.To E16,the volume of the central aqueduct shink by 42.8%.To E18,the volume is further reduced by 30.2%.The red nucleus,substantia nigra,and ventral tegmental area are relatively close to each other,and all locate at the ventral side of the aqueduct.With the expansion and development of the midbrain,they grow and develop along the ventral lateral to the midbrain.At E14,the volume of the red nuclei,substantia nigra,ventral tegmental area are small,as the development progresses,the volume increases continuously.To E16,their volume are increased by 581.1%,218.7%,and 51.1%,respectively.To E18,the corresponding increase is 43.2%,22.2%,and 162%,respectively.(3)Preparation of decellularized scaffold of midbrain and determination of its physical parameters.Cells are mostly removed from the scaffold,and pore structure inside the scaffold are formed well.The pore rate is 88.12±0.16%.The wall thickness of the scaffold iss 2.319±0.101?m.In addition,we co-cultured neural stem cells with the scaffold,and found that the scaffold has a good cell compatibility.Cells adhered to the scaffold for and grew.In conclusion,from the present results,we got know that:(1)All cells in the midbrain are derived from the aqueduct substrate and wing plate cells which forms neural tube.Internal nuclei in the midbrain has already developed at E14.As time progresses,they further differentiate together with the midbrain,and finally develope into a mature midbrain.(2)The volume of the internal constitutes increase as midbrain development,except the aqueduct of midbrain.(3)The basic parameters of decellularized midbrain scaffold are obtained.