Cytology II - Vet 2024-2025 PDF

Faculty of Veterinary Medicine Course name: Histology A CYTOLOGY –II (Non-membranous organelles, Cell inclusions & Nucleus) Dr/ Amel Marzouk Professor of Histology 2024-...

Faculty of Veterinary Medicine Course name: Histology A CYTOLOGY –II (Non-membranous organelles, Cell inclusions & Nucleus) Dr/ Amel Marzouk Professor of Histology 2024-2025  CYTOLOGY –II (Non-membranous organelles, Cell inclusions & Nucleus) Learning Objectives:  Enumerate the non-membranous cell organelles.  Mention the structure and functions of non-membranous cell organelles.  Identify the cell inclusions & list their types. Identify the structure of the nucleus & list its components. Define the cell cycle & mention its stages. Define the cell death & mention its types.  Non-membranous Cell Organelles 1- Ribosomes. 2- Centrosomes. 3- Microtubules 4- Microfilaments (3, 4 & 5 form the Cytoskeleton) 5- Intermediate filaments  Ribosomes - Structure: Ribosomes are composed of ribosomal RNA (rRNA) and protein. - With L.M: Cells rich in ribosomes are highly basophilic. - Types of ribosomes: 1- Attached to rough endoplasmic reticulum (RER). 2- Free in the cytoplasm. - Function:  Centrosomes - Structure: The centrosome is found close to the nucleus. The centrosome consists of two centrioles. Each centriole is formed of microtubules. - Function: form the mitotic spindle during cell division.  Cytoskeleton *Cytoskeleton is formed of: a. Microtubules (25 nm in diameter). b. Microfilaments (5-7 nm in diameter). c. Intermediate filaments (10 nm in diameter). *Function of Cytoskeleton: 1. Maintains the cell shape. 2. Structural support. 3. Important for cell movement.  Cell Inclusions - Types of cell inclusions: 1. Glycogen granules:  Are aggregates of carbohydrate.  Mainly stored in liver cells.  Stained with PAS stain. 2. Lipid droplets: Are aggregates of lipid. Mainly stored in fat cells. Stained with Sudan Black stain. 3. Pigments: Are aggregates of naturally colored material. Such as melanin pigment present in skin & eye. Examples of Cell Inclusions PAS stain of glycogen Sudan Black stain of lipid Melanin pigment in the eye (H&E stain)  The Nucleus *The nucleus contains the genetic information of the cell. *With L.M: -It stains basophilic. -It may appear: a- Vesicular nucleus (pale basophilic) such as the nucleus L.M. of Vesicular nucleus in liver cells (H&E) of liver cells. b- Dense nucleus (intensely basophilic) such as the nucleus of lymphocytes. LM of Dense nucleus in lymphocyte (H&E)  Components of The Nucleus The nucleus consists of: 1- Nuclear envelope. 2-Chromatin. 3- Nucleolus. 4- Nucleoplasm.  Nuclear Envelope -The nuclear envelope surrounds the nucleus. -It is formed of two membranes. - It has many nuclear pores which transport macromolecules between the nucleus &cytoplasm.  Chromatin - Structure: Chromatin is composed of DNA and proteins. - Types of Chromatin : 1- Euchromatin (the Active type): appears diffuse granular. 2- Heterochromatin (the Inactive type) appears coiled clumps.  Nucleolus - Function of the nucleolus: synthesis of ribosomes.  Cell Cycle - Definition: Cell cycle is the regular sequence of events that produce new cells. - Phases of Cell Cycle: 1- G1 Phase. 2- S Phase. 3- G2 Phase. 4- M Phase (Mitosis). What is G0 Phase?  Phases of Cell Cycle 1- G1 (Gap 1) Phase: is the longest phase. It is a period of protein synthesis and cell growth. 2- S (Synthesis) Phase: is the period of DNA replication. 3- G2 (Gap 2) Phase: is a short period of preparation for mitosis. 4- M (Mitosis) Phase: is the period of cell division that results in two new daughter cells. G0 phase: is the period in which the cells differentiate. During this period, the cell cycle is suspended.  Cell Death There are TWO main types of cell death: 1- Apoptosis. 2- Necrosis. Diagram of Types of cell death  Types of Cell Death 1- Apoptosis 2- Necrosis Physiological process Pathological process Programmed cell death Acute cell injury The cell shrinks The cell swells The cell forms apoptotic bodies The cell rupture and release its content Does not induce inflammation Induce inflammation Enumerate: 1. Non-membranous cell organelles. 2. Types of ribosomes. 3. Components of cytoskeleton. 4. Types of cell inclusions. 5. Components of the nucleus. 6. Types of cell death. 7. Phases of cell cycle. 8. Types of chromatin. 9. Differences between apoptosis and necrosis.  Complete: 1. The nucleus stains…………………… with H&E stain. 2. The nuclear envelope is formed of …………………….. 3. ….………….. is the active type of chromatin. 4. ……..……… is the inactive type of chromatin. 5. ………………. is the longest phase of the cell cycle. 6. ………………. is the period of DNA replication in the cell cycle. 7. ……………… is the period in which the cells differentiate and the cell cycle is suspended. 8. ………..………. is the regular sequence of events that produce new cells. 9. Examples of cell inclusions are ………..… , ………... and …………… 10. …………..……….. pigment is present in the skin and eye. 11. Glycogen is stained by ……………………..……….. stain. 12. Lipid is stained by ………………………….……….. stain.  Choose the correct answer: 1-Which of the following organelles is important for cell division? a. Lysosomes. b. Glycogen. c. Melanin. d. Centrosomes. 2- Which of the following is true about ribosomes? a. Basophilic. b. Synthesized in smooth endoplasmic reticulum. c. Power house of the cell. d. Rich in hydrolytic enzymes. 3- Which of the following is true about glycogen? a. A non-membranous organelle. b. Stained with PAS stain. c. Synthesize proteins. d. A pigment. 4- Which of the following is a character of the nuclear envelope? a. Have pores. b. Digest materials entering the cell. c. Synthesize lipids. d. Is stained with silver. 5- Which of the following is the period of DNA replication in the cell cycle? a. G1 phase. b. G2 phase. c. M phase. d. S phase. 6- Which of the following is a character of apoptosis? a. Inflammation. b. Rupture of the cell. c. Shrinkage of the cell. d. Swelling of the cell.  Lecture References - Junqueira's Basic Histology: Text and Atlas 17th Edition. Thank you