Zoology 145. Laboratory note

Transcription

1 King Saud University Faculty of Science Zoology department Zoology 145 Laboratory note Prepared by: Amal Awad Al-Harbi Supervision: Dr.Maha H. Daghastani Dr.Afrah F. Al-Khuriji Dr. Sherifa S. Hamed 1

2 Laboratory Sessions (1) A. The Microscope and its use. B. Cell structure: - Prokaryotes: Bacteria. - Eukaryotes: animal and plant cells. C. Types of eukaryotic animal cells. (2) Histology: A. Connective tissue. 1- Areolar connective tissue. 2- Hyaline cartilage. B. Nervous tissue. 1- Neurons. 2- Spinal cord. (3) Histology: Muscular tissue. 1- Striated muscles. 2- Cardiac muscles. 3- Smooth muscles. (4) Histology: A. Blood vessels. B. Kidney. (5) Histology: The digestive system. 1- Oesophagus. 2- Stomach. 2

3 (6) Histology: 1- Liver. 2- Testis. (7) Cell division. 1- Mitosis. 2- Meiosis. (8) Revision. (9) First final exam. (10) The Rat: 1- External features. 2- General viscera. 3- Endocrine system. (11) The Rat: 1- Urogenital system. 2- Nervous system. (12) A. Human genetics: 1- Blood Groups. 2- Other human traits. B. Revision. (13) Second final exam. 3

4 The Compound Microscope: MICROSCOPY The compound light microscope is one of the most important and useful tools of the biologist. It is used to study the structure of developing embryos, organization of tissues, cells and its organelles, along with many other important applications. Since many of the exercises in this course will require the use of the compound microscope, it is important to review some aspects of its construction, use and care. There are numerous models of compound microscopes, the microscope assigned for your use may differ from the one illustrated but the operating principles and procedures will be similar. A microscope must be carried with both hands. Grasp the arm of the microscope firmly with one hand and support the base with the other hand. Place it gently on your desk with the arm facing you. Always remember that this expensive scientific instrument is assigned to you for your use and safe-keeping. Be sure that you use the microscope properly and carefully, and that you keep it in good condition. Promptly notify your laboratory instructor if you observe any malfunction or if you have any difficulty in the use of your microscope. 4

5 Parts of the Microscope: They can be grouped in three systems: 1- The mounting and movement system. 2- The magnification system. 3- The illumination system. 5

6 1-The mounting and movement system: Part The base The arm The stage The coarse focusing knob The fine focusing knob The body tube The revolving nose-piece Function Supporting stand. Supports the upper part of the microscope. The horizontal platform upon which the slide rests. To rise and lower the stage from the objective lenses. Focusing for the sharpest image. Carry the ocular lenses at one end and the objective lenses at the other end. Attached to the objective lenses and moves the different objective lenses into position over the stage aperture. 2-The magnification system: The objective lenses There are three or four lenses, each one gives a different magnification. According to their power of magnification, they are known as: a) The scanning objective lens which has a power of magnification 3.5x,4x or 5x. b) The low power objective lens which has a 6

7 power of magnification 10x or 20x. c) The high power objective lens which has a power of magnification 40x. d) The oil immersion objective lens which magnifies the object 100x. The ocular lenses or the eye-piece They are used to examine and magnify the image produced by the objective lens. They vary in their power, the commonly used ones are 5x to 10x and 15x. 3-The illumination system: The part The illuminator The condenser The iris diaphragm The function Source of light. Collect and concentrate the light towards the slide. Control the amount of light. How to use the microscope? Magnification: The magnification of an object is determined by multiplying the power of the objective lens by the power of the ocular lens. Example: 10x ocular 40x objective = 400x total magnification. 7

8 THE CELL STRUCTURE Cells are the basic units of biological structure and function. They possess the following three essential features: I-The cell membrane (plasma membrane): -The cell membrane is an outer membrane which separates the cell from the external environment. II- The genetic material: -The genetic material is composed of DNA. - It directs and controls all the cell activities, and enables it to reproduce passing on its characteristics to its offspring. III- The cytoplasm: - The cytoplasm contains a large variety of molecules as well as formed bodies called organelles. Cell types: -Two major types of cells are known according to the arrangement of the genetic material and the contents of the cytoplasm. 1- Prokaryotes. 2-Eukaryotes. 8

9 Prokaryotes Eukaryotes name Pro=before, karyon=nucleus Eu=true, karyon=nucleus nucleus Not present. The genetic material is in the form of a large, single, circular molecule of DNA found diffuse in the cytoplasm. The region where the DNA is found is known as the nucleiod. Present. DNA is associated with proteins in a complex structure known as the chromatin, which is surrounded by a double membrane called the nuclear envelope, this envelope separates the chromatin from the cytoplasm in a distinct nucleus. - Eukaryotic cells vary greatly in size and shape. There are two types of eukaryotic cells: 1-Animal cells: which have a cell membrane and no cell wall. 2-Plant cell: which have a cell membrane and cell wall. Characteristics of the different cell types: 1-Prokaryotes (Bacteria): Type of cells Description of the shape Location Bascillus Coccus Rod shaped, occur in strands. Round shaped, occur in colonies and strands. Free living or found in other organism. Free living or found in other organism. 9

10 Bacteria Bascillus Coccus Draw a labeled diagram in the space provided, notice their magnification: Prokaryotes (Bacteria): Bascillus coccus 11

11 2-Eukaryotes: Type of cells Description of the shape Location a)plant cells: e.g. Onion cells. b)animal cells: e.g. epithelial cells. 1-squamous epithelium. 2-cuboidal epithelium. Rectangular-with eccentric nucleus. Cell wall clearly seen. Flat cells having an irregular border with flattened nuclei. Cuboidal in shape with large central spherical nuclei. Onion-leaves in onion bulb. 1-Endothelium. 2-Bowman, s capsules. 3-Lung alveoli. 1-Thyroid gland. 2-Ovary 3-Large collecting tubule in the kidney. 3-columnar epithelium. Tall(rectangular), column-like cells with oval or elongated nucleus basal in position. 1-Stomach. 2-Intestine. 11

12 Eukaryotes (A) Plant cells: Draw a labeled diagram in the space provided, notice their magnification: - Onion leaf epidermis (plant cell): (mag..x) (B) Animal cells: (1) Squamous epithelium: 12

13 Mouth mucosa. (Top view) Bowman ' s capsule. (Side view) Draw a labeled diagram in the space provided, notice their magnification: 1- Mouth mucosa: Squamous cells (top view) (mag..x). 2- Bowman ' s capsule: Squamous cells (Side view) (mag..x). (2) Cuboidal epithelium: 13

14 Collecting tubules in the kidney Thyroid gland Draw a labeled diagram in the space provided, notice their magnification: 1- Cuboidal epithelium: Collecting tubules in the kidney. (mag. X) 2- Cuboidal epithelium: Thyroid gland. (mag..x) 14

15 (3) Columnar epithelium: Draw a labeled diagram in the space provided, notice their magnification: - Columnar epithelium: (Section in Stomach) (mag..x) 15

16 THE CONNECTIVE TISSUE General characteristics : The connective tissue, connects, holds and supports body tissues and organs together. It is characterized by the presence of several types of cells widely separated and immersed in an abundant intercellular component formed by these cells. Present almost in all parts of the body. Constituents of connective tissue I- Connective tissue fibers II- Amorphus extracellular substance or matrix III-Connective tissue cells I-There are two types of connective tissue fibers a-collagen fibers -The most numerous fibers in connective tissue. - Fresh collagen fibers which are colorless but when Present in great number they are white. -They are inelastic, flexible and have a great tensile strength. -The individual fibers do not branch while the bundles of fibers often do. 16

17 b--elastic fibers : -Fresh elastic fibers are yellow and unbranched. -They are capable of stretching to 1.5 times their length. -Elastic fibers are abundant in large blood vessels e.g.aorta. II-Amorphous ground substance which is: a) soft as in the connective tissue proper. b) liquid as in blood and lymph. c) semisolid and solid as in cartilage and bone, respectively, which make the skeletal tissue. - Classification of Connective tissue according to the structural characteristic of the tissue 1-Areolar Connective Tissue Areolar connective tissue is the most widespread connective tissue of the body. -Areolar connective tissue is flexible, richly vascular and support epithelial tissue. - All types of cells are represented with predominance of fibroblast and macrophages in areolar connective tissue. -All types of fibers (collagen and elastic) are arranged in no particular pattern, run in all directions and form a loose network in the intercellular 17

18 material in areolar connective tissue. - Areolar connective tissue has a good amount of ground substance. Areolar connective tissue surrounds and supports the blood vessels. Areolar connective tissue Draw a labeled diagram in the space provided, notice their magnification: - Areolar connective tissue. (mag..x) 18

19 Draw a labeled diagram in the space provided, notice their magnification: - Areolar connective tissue. (mag..x) 19

20 2-Cartilage - Cartilage is a specialized type of connective tissue which is firm. - The firm matrix allows the tissue to bear mechanical stress. - Cartilage support soft tissue. - It acts as a shock absorbant and it also provides sliding surfaces for bones inside joint cavities, facilitating bone movement. - It also keeps the patency of the respiratory tract. Cartilage of the body is classified according to: 1.The nature of the matrix. 2.The type of its fibers. The hyaline cartilage:(example :trachea of rabbit) - Components of hyaline cartilage: 1- It is called hyaline (hyalos=gloss) because of its glossy, whitish blue appearance in the fresh state and semisolid. 2- Cartilage cells are named chondroblasts and chondrocytes. 21

21 3- Collagen fibers are embedded in the matrix. 4- Hyaline Cartilage is usually covered by a vascular fibro-cellular membrane called perichondrium which is essential for growth and maintenance of cartilage. The Hyaline cartilage (T.S. in costal cartilage). Draw a labeled diagram in the space provided, notice their magnification: T.S. of a hyaline cartilage. (mag..x). 21

22 THE NERVOUS TISSUE The nervous system is divided anatomically into: 1- The central nervous system (CNS), consisting of the brain and the spinal cord. 2- The peripheral nervous system (PNS), composed of nerve fibers forming the cranial and spinal nerves and the ganglia. The nervous tissue consists of two cell classes: 1- The neurons, which are the functional units transmitting the nerve impulses. 2- The supporting cells (glial cell or neuroglia), which support, nourish and insulate the neurons and perform the defense processes in the nervous system. They are mainly of two types: a) Neuroglia cells inside the CNS. b) Schwann cells outside the CNS (in the PNS). Structure of the neuron: Neurons have diverse sizes and shapes, but each typically consists of the cell body, an axon and dendrites: 1- The cell body: it is also called the perikaryon or soma. It contains the nucleus,cytoplsmic organelle (mitochondria, Golgi complexes, endoplasmic reticulum ) and cytoplasmic inclusions (Nissl bodies). 22

23 2- The dendrites: they are multiple cytoplasmic processes specialized in receiving stimuli and transmitting them to the cell body. 3- The axon: a single long process specialized in conducting nerve impulses to other cells. The distal part of the axon is usually branched and constitutes the terminal arborization forming synapses with other nerve cells. The axon emerges from the cell body at the axon hillock. The spinal cord: It is a cylindrical tissue in the form of a hollow tube lying within the spinal cavity of the vertebral column and is surrounded closely by a loose connective tissue layer called the pia matter. In the center, there is a central canal lined by simple epithelial cells. In cross section, the spinal cord appears to be more or less oval with two deep dorsal and ventral grooves known as the dorsal fissure and the ventral fissure, respectively. These fissures divide the cord into right and left symmetrical halves. The ventral fissure is deeper and wider than the dorsal fissure. According to its color in the fresh condition, the spinal cord in cross section is differentiated into: 23

24 a) A central zone called the gray matter, shaped like the letter H and contains the nerve cell bodies and glial (neuroglia) cells. b) A peripheral zone called the white matter composed entirely of myelinated nerve fibers and neuroglia cells. The two dorsal limbs of the H-shaped gray matter are called the dorsal horns and the two shorter and broader limbs are called the ventral horns. The two central bars of the H, passing transversely above and below the central canal, are called the dorsal and ventral commissures. 24

25 145 ZOO THE NERVOUS TISSUE T.S in The Spinal Cord of The Rabbit dorsal dorsalhorn horn dorsal fissure dorsal commissure Neuroglia cells central canal Nerve fibers blood vessel grey matter white white matter matter pia matter Bodies Bodies of of neurons neurons ventral ventral horn horn ventral commissure ventral fissure Neuron Glial cell Nucleus Grey matter Nerve fibers Nerve fiber White matter 25

26 T.S. of Spinal cord T.S. of the Spinal cord Enlarged part of White matter (Nerve fibers) T.S. of the Spinal cord Enlarged part of Gray matter (Cell body of the neuron and Glial cell nucleus) 26

27 Draw a labeled diagram in the space provided, notice their magnification: - T.S. of Spinal cord. (mag..x). 27

28 THE MUSCULAR TISSUE General characteristics of the muscular tissues: The cells of the muscular tissues are elongated elements, named muscle fibers. 1- The cytoplasm of the muscle fiber, the sarcoplasm, contains myofibrils. These myofibrils are made up of the proteins actin and myosin. 2- The plasma membrane of the muscle fiber is called the sarcolemma. 3- Muscle fibers are called striated or smooth (non-striated) according to the presence or absence of striations. 4- Muscle fibers may be voluntary (when their contraction is under the control of will), or involuntary (when it is beyond the control of will). 5- There are three types of muscle fibers: a) Skeletal muscles, which are striated and voluntary. b) Smooth muscles, which are unstriated and involuntary. c) Cardiac muscles, which are striated and involuntary. A) The skeletal muscles (striated) The skeletal muscles are voluntary and attached to the skeleton. The skeletal muscle fibers are striated. 28

29 Each muscle fiber is elongated, unbranched, cylindrical cell, with numerous peripheral flattened nuclei. T.S of skeletal muscle: - Each individual muscle fiber is surrounded by a delicate connective tissue, the endomysium. - Bundles or groups of fibers are wrapped by a dense connective tissue called the perimysium. - The whole muscle (formed of several bundles) is covered by a dense connective tissue sheath, the epimysium. 29

30 L.S. of Skeletal muscle T.S. of Skeletal muscle Draw a labeled diagram in the space provided, notice their magnification: 1- L.S. of Skeletal muscle. (mag..x). 2- T.S. of Skeletal muscle. (mag..x). 31

31 B) The Smooth Muscle (unstriated) The smooth muscle fibers are unstriated and contract under the control of the autonomic nervous system, i.e. involuntary. The smooth muscle fibers are elongated, spindle- shaped cells. The nucleus is elongated or rod-shaped and centrally located in the cytoplasm at the widest part of the cell. These muscles are present in the wall of blood vessels, digestive, respiratory, urinary and reproduction systems. L.S. of Smooth muscle Draw a labeled diagram in the space provided, notice their magnification: 31

32 C) The Cardiac Muscles These muscles are present only in the heart. The cardiac muscle fibers are striated and involuntary. Cardiac muscle fibers are elongated, branched and mononucleated. The nuclei are oval and centrally located. There are darkly-stained, transversely oriented bands scattered through cardiac muscle fibers; points of end-to-end contact between contiguous myocardial fibers which are known as intercalated discs. L.S. of Cardiac muscle 32

33 Draw a labeled diagram in the space provided, notice their magnification: L.S of Cardiac muscle. (mag..x). 33

34 Types of muscle fibers Skeletal Smooth (Striated muscle) (Unstriated muscle) Cardiac muscle Shape An elongated, An elongated, unbranched, An elongated, branched, cylindrical cell, with spindle-shaped cells mononucleate or numerous peripheral with pointed ends. binucleate. flattened nuclei. Nucleus An elongated or rodshapedshaped. An elongated or rod- shape Oval. Centrally located in Nucleus the cytoplasm at the Peripheral. location widest part of the Centrally located. cell. Striation Transversely striated. unstriated and contract under the control of the Striated. autonomic nervous system. Voluntariness Voluntary. Involuntary. Involuntary. In the blood vessels, Location digestive, Attached to the respiratory, urinary skeleton. and reproduction system. In the heart. 34

35 THE BLOOD VESSELS The circulatory system consists of the blood and lymphatic vascular system. The vascular system is composed of: 1- The heart which pumps the blood. 2- The arteries which carry oxygenated blood and nutrients to the tissues. They becomes thinner as they branch forming arterioles. 3- The capillaries which consists of a diffuse network of thin tubules through which gas exchange between blood and tissues takes place. 4- The veins which carry deoxygenated blood, rich in carbon dioxide and other metabolic products from the tissues to the heart. Histological structure of the blood vessels: All blood vessels have a number of structural features in common. They are composed of three layers called tunica intima, tunica media and tunica adventitia. Tunica intima: (This is the innermost layer that faces the blood stream) o This layer consists of 2 components: 1. A layer of simple squamous epithelium cells (endothelium) lines the vessel with its basal lamina. 2. A subendothelial layer ( a very thin layer of fibrocollagenous support tissue). Tunica media : o It is consists of layers of circular smooth muscle cells with elastic and 35

36 collagen fibers interposed among them. Tunica adventitia: o It is a connective tissue layer consisting of longitudinally collagen and elastic fibers. o This layer gradually becomes continuous with the enveloping connective tissue of the organ through which the vessel is running. The Artery o Tunica intima: The flattened endothelium is separated from the media by a well developed layer of elastic connective tissues, called the internal elastic lamina. o Tunica media: This layer is the thickest layer of the vessel wall. It consists mainly of circular smooth muscle cells, elastic and collagen fibers. o Tunica adventitia: The areolar connective tissue with loosely arranged cells and fibers is especially rich in elastic fibers. The Vein o Tunica intima: The endothelial layer is not separated from the media by the internal elastic lamina. o Tunica media: This layer is much thinner than that of the artery and contains more collagen than elastic fibers. o Tunica adventitia: This is the thickest layer of the vein wall and contains mainly collagen fibers. 36

37 T.S of Blood Vessels (Artery & Vein) 37

38 T.S of the Artery T.S of the Vein Draw a labeled diagram in the space provided, notice their magnification: 1- T.S of an artery. (mag..x). 2- T.S of a vein. (mag..x). 38