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The discovery of tissue: What are the roots of why biologists call it "tissue"?
In biology, a "tissue" is defined as a group of similar cells and their extracellular matrix. These cells share the same embryonic origin and work together to perform specific functions. Biological organization levels of tissue lie between cells and complete organs. From this perspective, organs are formed by the functional aggregation of multiple tissues. The organizational structure of organisms follows a strict hierarchy: cells < tissues < organs < organ systems < organisms.
The word "tissue" in English comes from the French "tissu", which is the past participle of the verb "tisser" (to knit). Histology is the study of tissues, and those related to disease are called histopathology. Xavier Bichat is known as the father of histology. His research brought new perspectives to anatomy and led to an appreciation of the importance of tissue.
"Tissue is a core element of human anatomy, and organs can be viewed as collections of various tissues."
Tools for studying tissue include tissue blocks fixed in paraffin, the use of tissue stains, and light microscopy. With the development of electron microscopy, immunofluorescence techniques, and cryosectioning techniques, we can observe tissues more clearly. This allows for in-depth analysis of tissue structure in health and disease, leading to important improvements in medical diagnosis and prognosis.
Plant tissue
In plant anatomy, tissues are broadly divided into three tissue systems: epidermal tissue, basal tissue, and vascular tissue.
- Epidermal tissue: forms the outer layer of leaves and young plants.
- Vascular tissue: Mainly composed of xylem and phloem, responsible for internal liquid and nutrient transport.
- Basic tissue: It is less differentiated and performs photosynthesis to produce and store nutrients.
Plant tissues can also be divided into two types: meristems and permanent tissues.
Meristem
Consists of actively dividing cells that promote growth in length and thickness of the plant. The main types of meristems include the following:
- Apical meristem: Found at the growing tips of stems and roots.
- Lateral meristem: mainly causes the growth of organ diameter.
- Insertive meristem: located between permanent tissues and responsible for the growth of plant length.
"The cells of the meristem have extremely thin cell walls and are tightly arranged."
Permanent organization
Permanent tissue is composed of cells that have differentiated from meristematic tissue and have lost the ability to divide, and remain permanently stationary in the plant body. According to the shape and function of cells, permanent tissues can be divided into simple permanent tissues and complex permanent tissues.
Simple permanent organization
The cells of simple permanent tissues are similar in origin, structure and function. They mainly include the following types:
- Parenchyma: Provides support and stores food.
- Sclerenchyma: Provides mechanical support and makes plants tougher.
- Hard tissue: composed of dead cells that provide strong support due to thick secondary cell walls.
Complex permanent organization
Complex permanent tissues are composed of a variety of cells that work together to complete certain functions. The most important complex tissues are xylem and phloem.
Animal tissue
Animal tissues can be divided into four types: connective tissue, muscle tissue, nervous tissue and epithelial tissue. The specific manifestations of these tissues vary from organism to organism.
Epithelial tissue
Epithelial tissue covers the surface of the organ, forming a protective layer. The main functions of this tissue are protection, secretion and absorption. Epithelial cells are closely connected and form a selectively permeable barrier.
Connective tissue
Connective tissue is characterized by cells separated by inactive material, a matrix that can be liquid or solid. Connective tissue gives organs their shape and maintains their position.
Muscle tissue
Muscle cells (myocytes) form tissues with the ability to move and are divided into three categories: smooth muscle, skeletal muscle, and cardiac muscle.
Nervous tissue
Nervous tissue is composed of cells in the central nervous system and peripheral nervous system and is mainly responsible for the transmission and processing of information.
Conclusion
The concept of tissue has driven the development of biology, explaining how cells and organs integrate and function. Greater knowledge about tissues not only improves our understanding of biological structures but also has important applications in medicine. Have you ever thought about how tissue learning might influence our understanding of health and disease in future research?
