Tong Dizhou is a biologist, educator and social activist from Yinxian County, Zhejiang Province (now Yinzhou District, Ningbo City). He is the main founder of experimental embryology in China, the founder of marine science research in China and an outstanding leader in biological science research. He pioneered China's "cloning" technology and is known as "the father of cloning in China".
1927 Tong Dizhou graduated from Fudan University and later taught in the Biology Department of Nanjing Central University. Since 1934, he has taught in Shandong University, Central University, Tongji University and Fudan University. 1948 was elected as an academician of academia sinica; 195 1 year, served as vice president of Shandong university; 1955 was elected as an academician of China Academy of Sciences; 1957, Director of Institute of Marine Biology, China Academy of Sciences; 1978, vice president of China academy of sciences.
Tong Dizhou revealed the polarity of embryonic development by studying amphibians and fishes. Through the study on the individual development and taxonomic status of amphioxus, great achievements have been made in the study of nuclear-cytoplasmic relationship; 1963 completed the research on nuclear transfer of fish for the first time, which laid the foundation for the completion of interspecific cloning of fish and somatic cloning of adult crucian carp in China in the 1970s and 1980s.
What is embryology?
Embryology, also known as genetics, is a science that studies the origin and development of individuals. The research contents include the gestation of life, the process of embryo development, the morphological and physiological evolution characteristics of each development stage, the adaptation, variation and inheritance of living conditions in the development process, and the unified law of individual development and systematic development.
Human embryology is a subject that studies the occurrence and development of human body. Broadly speaking, it includes the beginning of life after fertilization, the prenatal development of embryos and fetuses in the uterus, and the whole postpartum development history from newborns, infants, children, adolescence to adulthood, aging and death. The whole process from fertilized egg to adult individual, and then to aging and death is called individual development.
It includes the following two stages of development.
1. Prenatal development: ① Sperm fertilization, cleavage and implantation, lasting for 2 weeks: ② Embryonic period: 2-8 weeks; ③ Fetal period: from the third month to delivery.
2. Postpartum development: ① Newborn: from birth to 2 weeks after birth; 2 infancy: from the third week after birth, the body is upright (about one year old); ③ Childhood: from 15 months after birth to 13 years old, in which deciduous teeth are 2-6 years old, permanent teeth are 7- 10 years old, before puberty,10-/3 years old, and ④ adolescence:14 years old. ⑤ Adult period: before the age of 25, the skeletal system ossifies and its growth is basically completed, and then it grows very slowly; ⑤ Aging and death.
Human embryology usually focuses on the contents of intrauterine development, including the morphological formation from a simple fertilized egg to a complex multicellular embryo, the differentiation of tissues and organs and the establishment of physiological functions; The relationship between the construction and evolution of anatomical positions of various parts of the body during development, and how to lead to disorder, deformity and abnormal pathological phenomena in normal development. The intrauterine development stage from fertilized egg to fetus before birth lasts about 40 weeks.
Embryo development begins with the combination of sperm and egg, and the fertilized egg develops into an individual, which means the full expression of genetic material carried by sperm and egg and includes the whole process of growth, differentiation and maturity in the individual life history.
From the biological significance of species, the limited individual life history is only a small fragment in the continuous history of species generations. Organisms continue their lives from generation to generation through reproduction, which is both hereditary and mutated and eliminated by natural selection. The continuation of this life history of species is called phylogeny or phylogeny.
The genetic traits of species are arranged on the DNA chain of biological macromolecules in the form of codes and stored in germ cells. The development of life history begins with the combination of germ cells. Sperm and egg show genetic information from their parents in a certain time sequence and spatial relationship during development.
In fact, heredity and development are two inseparable aspects of individual development, heredity is the basis of development, and development is the process in which genetic code (genotype) is expressed in phenotype. Therefore, on the one hand, the development process is to grow and differentiate on the basis of the genetic material of this species to maintain the genetic characteristics of this species; On the other hand, following the law of biological evolution, some * * * identical structural features of embryonic development appear repeatedly in embryonic stage, and at the same time, they evolve through long-term natural selection, in which the individual development process is the main link of natural selection.
How do cells with complete genetic information from parents selectively express different genes to differentiate different tissues and organs? What substance or mechanism regulates gene activity and its expression time, spatial order, and how errors in transcription and translation of transmission codes lead to genetic diseases and abnormal differentiation. These problems are of great theoretical and practical significance in embryology and cytogenetics.
Individual development can be different from each other in the specific development details before or after birth due to different species, but it follows the same rules in development procedures, that is, they all go through the same development stages of cleavage, morula, blastocyst, gastrula, axonal embryo, somatic stage, fetal stage and late birth.
In addition, multicellular organisms evolved from single-celled fertilized eggs have to go through several basic development modes, such as cell proliferation, cell differentiation, morphogenesis, metabolism and growth, to further develop into individuals with complex organs. This is the only way for individuals to grow and develop before and after birth.