It has been more than 300 years since man first discovered cells. With the progress of science and technology and experimental means, people's understanding of cells has gone from shallow to deep, and from the outside to the inside, which has led to the rise and development of cell biology today. According to its development process, it can be divided into four periods, namely, the establishment of cell theory, the classical period of cytology, the development of experimental cytology and the rise of cell biology.
(A) the establishment of cell theory
1665, British physicist R. Hooke observed cork (oak bark) and other plant tissues with a self-made microscope, and published a book called Micrographics, which described that cork is composed of many small cells, which are called "cells". In fact, what Hooke saw in cork tissue was only the cell wall of dead plant cells. This is the first time that human beings have seen the outline of cells, and people's understanding of biomorphology has entered the microscopic world of cells for the first time. In 1675 (A.V.Leeuwenhoekia), protozoa and animal sperm in pond water were observed successively with a self-made high-power magnifying glass, and red blood cells were found in frog blood. 1683, he saw bacteria in tartar again. 183 1 year, R. Brown found the nucleus in the epidermal cells of orchid leaves. 1835, Duyaldan first discovered that the cells of lower animals contain transparent colloidal substances, which are called "sarcoidosis". 1836, Valentine discovered nucleoli in the nucleus of connective tissue. So far, the basic structure of cells has been discovered.
Before the19th century, many scholars focused on the microstructure of cells, mainly engaged in the description of morphology, without theoretically expounding and summarizing the significance of cells in various organisms. 1838- 1839, German botanist M.J. Schleiden and zoologist Wang Shi put forward the cell theory for the first time on the basis of their own research and summary of previous work. They believe that "all living things, from single cells to higher animals and plants, are composed of cells;" Cell is the basic unit of biological morphological structure and functional activities. "This proves the unity of biology and the same origin of * * *. Engels once spoke highly of the establishment of cell theory, which was considered as one of the three major discoveries of natural science in19th century (cell theory, Darwinian evolution theory, energy transformation and conservation law). He pointed out that the first and third discoveries have greatly advanced our understanding of the relationship between natural processes: the cell was discovered for the first time, and it was found that the cell was such a unit that the whole plant and animal body developed from its reproduction and differentiation. As a result of this discovery, we not only know that all higher organisms develop and grow according to the same law, but also point out that organisms can change their species through the ability of cell variation, thus achieving a higher development path than individual development. It can be seen that only after the establishment of cell theory can it be clearly put forward that cells are the units of biological organism structure and life activities, and also the basis of individual development and systematic development of organisms. Obviously, the establishment of cell theory is an important milestone in the development of cytology, which has rapidly developed into a new independent discipline and the starting point of the development of cell biology.
Once the cell theory was founded, it quickly penetrated into various fields. 1885, German pathologist R.Virchow applied the cell theory to pathology, proved that the pathological process was carried out in cells and tissues, and put forward the famous assertion that "diseases are caused by external forces", which developed cell pathology and supported and enriched the cell theory.
(2) The classical period of cytology
/kloc-From the mid-9th century to the early 20th century, cytology flourished, and the research method was mainly morphological description of microscope I, which was called the classic period of cytology.
During this period, the first is the innovation of experimental technology. The main feature of this study is to observe the morphological structure and mitotic activity of cells under optical microscope by using fixation and staining techniques. Corti( 185 1 year) and Hartig( 1854) were stained with magenta, while B3hm (1865) was stained with hematoxylin. Oschatz designed the first microtome, and Ernest Abbe' (1887) designed a compound microscope with achromatic objective lens, condenser under the stage and illumination. These techniques and instruments have played an important role in observing cell morphology and microstructure.
In Remak of 184 1, remarque observed the direct division of chicken embryo blood cells. Later, Fleming discovered indirect division in animal cells and strassburger in plant cells. In 1882, Fleming called it direct mitosis and indirect mitosis. 1883, van Beneden and 1886, respectively, found meiosis in animal and plant cells in Strasbourg. In addition, Hertzwig also discovered the fertilization of eggs and the fusion of sperm and eggs. 1888, Waldell named the chromosomes in mitotic nuclei as chromosomes.
At the end of 19, people paid more attention to the morphological observation of cytoplasm, and several important organelles were observed one after another. Van Beneden and Boveri discovered centrosome in 1883, Banda mitochondria in 1897 and Golgi apparatus in 1898. Because of many discoveries, we have a deeper understanding of the complexity of cell structure.
(3) the development of experimental cytology
The development period of experimental cytology is from the early to the middle of the 20th century. During this period, the study of cytology shifted from the observation of morphological structure to the study of physiological function, biochemistry and genetic development mechanism. Using the new technologies and methods in the 20th century, with the infiltration of adjacent disciplines, cytology and related disciplines were infiltrated by experimental means, thus gradually forming some branches. Especially in the later stage of this stage, experimental cytology has developed rapidly due to the application of in vitro culture technology.
From 65438 to 0887, O.Hertwig and R. H. studied the nuclear-cytoplasmic relationship during the fertilization of sea urchin eggs and the development of ascaris eggs by experimental methods, and closely combined cytology with experimental embryology to develop experimental cytology. Since then, people have widely used experimental means and analytical methods to study some basic problems in cytology, which has opened up a new way for cytology research. From the rediscovery of Mendel's inheritance law in 1900 to the "chromosome inheritance theory" put forward by Boveri (T. Boveri) and W. S. Sutton in 1902, and then to Morgan's "gene theory" in 1926. During 1943, Cloude used a high-speed centrifuge to separate the nucleus and various organelles (such as mitochondria, chloroplasts, microsomes, etc.). ) were isolated from living cells and their physiological activities were studied respectively, which played a great role in understanding the physiological functions of various organelles and the distribution of enzymes. In cytochemistry, in 1924, Fuergen initiated the nuclear staining reaction, that is, Fuergen staining method, and determined the DNA in the nucleus. Then, in 1940, Brachet stained the cells with Unna dye and determined the RNA in the cells. At the same time, kasper Sen used ultraviolet spectrophotometry to determine the content of DNA in cells. The experiment also shows that the synthesis of protein may be related to RNA.
Since the 1940 s, the application of electron microscope has made the study of cell morphology go deep into submicroscopic level. 1933, ruska designed and manufactured the first electron microscope, and its performance far exceeded that of optical microscope. The resolution of the electron microscope has been improved from the initial 500 nanometers to the present tens of nanometers. The magnification can reach hundreds of thousands of times. 1949, Soverdlow invented isobutyric acid theorem, 1952, Paradi used osmium acid fixation method, 1953, and he designed a slicer for ultra-thin slices. Therefore, many scholars have observed the ultrastructure of various organelles in cells with electron microscope technology, such as endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes and so on. Therefore, the understanding of cytoplasmic structure and function? Further understanding makes cytological research develop in an all-round way.
(D) the rise of cell biology
Since 1950s, the research on the structure and function of cells has been gradually carried out at the molecular level. The research results in this field and the great achievements in molecular biology have greatly promoted the rise and development of cell biology.
In the 1940s, with the mutual penetration and combination of biochemistry, microbiology and genetics, molecular biology began to sprout. 194 1 year, Bedell and Tatum put forward the theory of "one gene and one enzyme". 1944, avery and others proved that DNA is genetic material in biotransformation experiments. 1948, Boivin et al. put forward the theory of DNA content invariance from determining the DNA content of germ cells and various somatic cells. In 1953, Watson and Crick obtained the molecular structure model of DNA double helix by X-ray diffraction. This epoch-making achievement laid the foundation of molecular biology. 1956, kornberg obtained DNA polymerase from the extract of Escherichia coli, and used the single-stranded DNA fragment of this strain as primer to successfully synthesize the complementary strand of DNA fragment in vitro for the first time. 1958, Meselson and others analyzed the process of DNA replication by radioisotope and gradient centrifugation, and proved that DNA replication is "semi-conservative". In the same year, Crick founded the "central rule" of genetic information transmission. 196 1 year, nirenberg and Mathai determined the "code" of each amino acid through the study of ribonucleic acid. In the same year, Jacob and Monod put forward the operon theory. Because these new achievements, new concepts and new technologies of molecular biology have penetrated into all fields of cytology, it is a new branch of biology to study the growth, development, inheritance, variation, metabolism, immunity, origin and evolution of cells from molecular level, subcellular level and whole cell level, that is, cytology has developed into the stage of cell biology. From 1965, E.D.P.Derobetis renamed the original "common cytology" to "cell biology", and from 1976, it was marked by the first international conference on cell biology held in Boston, USA. So far, the research work of cell biology has made rapid progress at the molecular level, and cell biology has developed into cell and molecular biology.