The Morphological And Histochemical Study On The Development Of Mouse Embryo Organs

Most of present the studies on auxology regulating are particular on the embryonic development after birth and the mechanism of focused embryonic stem cells (ES cells), gene expresons of many cellular factor contact by in vitro separation, culture, observation and investigation in vitro. However, there are few papers on the whole process of embryogenesis in vivo are reported. In this study, we try to explore the origin, migration and morphological changes of the genital gland, skin and liver during various stages of mouse embryogenesis,solving the problems puzzled the embryogenesis researchers providing histological reference for the further studies on regulating mechanism of emtryonic development and proliferation.Our experiments include four parts.Part 1: Slice-making of mouse embryos. In this paper, we introduced an efficient method to make the tissue slices of mouse embryos. The embryos of mouse from E10 to E20 were fixed in Bouin which is helps keep the microstructure of cells and tissue. 24 hours later, the tissues were dehydrated by gradient ethanol, transparent in toluene, immersed in paraffin, and then made into slices in 4um. The study of the whole mouse embryo by different morphological staining would show us the morphological and chemical changes during various stages of embyogenesis. Furthermore, it is convenient for the continuous observation of mouse embryogenesis and the migration of primordial embryonic cells. In addition, the slice-making of mouse embryos also provides us a basis for the further study of embryogenesis.Part 2: Study on the development of mouse genital gland. To explore the developmental process of genital gland, we observed the whole mouse genital gland at various stages of embryogenesis by immunohistochemical and morphological staining. The morphological study displayed that the germinal epithelium occurred 10 days after fertilization, then the genital ridge came into being (E11), undifferentiated genital glands began to be observed (E12). On the 13th day of embryogenesis the gender of embryos could be identified. The male's genital gland developed into testis (E14), whereas the female's developed into ovary (E16). On the 20th day, there existed spermatogenous cells and spermatocytes laying monolayer in the seminiferous tubules. There were also some primitive follicles in the cortexin the ovary. It seems that E11 to E12 is the most favorite period for the development of primordial germ cells.Immunohistochemical staining of Oct-4 showed that there lived positive cells specially in the primordial germ cell on the 10 day of embryogenesis. With the development of genital glands, Oct-4 positive cells became increased gradually, reaching the pinnacle (E14 to El6), and began to decrease 17 days after the fertilization. The expression of Oct-4 is probably important to keep the undifferentiated state of primordial germ cells which could proliferate and differentiate into other sources of cells.Part 3: Study on the development of mouse skin. The skin of E10 mainly consisted of one laryer of flattented cells with no obvious difference from the deep-seated mesenchymal cells.it became double-layered cells E11 to E12,and differentiate into three-layer cells and form the epidermal ridge in E13. In this period, the loose connective tissue appeared in the dermis , with the synthesis of collagens. The anlage of hair follicle appeared in the skin on the 14th day of the embryogenesis. Subsequently, the epidermis attached closeiy to dermis with the proliferation of the skin cells (El4), and the structure of the skin tended to be distinct and mature (E15 to E16), similar to that of the adult (El7) without obvious changes after that (E18). The time between 13 rd to 14th day during the embryogenesis might be the optimic period for the skin to grow and differentiate ,which implies that the skin stem cells could be well separated during this period. In addition, nestin was staining was positive in the skin during various stages of the development by immunohistochemical technique, nestin was fir...