Foundation Academy for Sciences & Technology 

FAST 

Biology Practical Manual

 

 

Batterjee Medical College for Sciences & Technology 

Second Semester 2010‐11 

2

Batterjee Medical College

Jeddah, Saudi Arabia

Type of Document: BIOLOGY

Laboratory manual

Policy Number:

Title: Laboratory manual Date Prepared:

7-2-2011 Date approved:

Policy Linked To:

Department of Biology

Effective date: Revision Due Date:

Prepared by:- Rehana Imtiaz

Signature :‐ Date 7-2-2011

Job Title: Biology-lab Lecturer

Concerned by:

Dr. Osama Abdel Raouf Signature :‐ Job Title:

Director of FAST Reviewed by: 

Mrs.Salwa Kamel Signature :‐ Job Title:

Acting  Director of  FAST

Approved by: Dr. Khalid Batterjee

Signature :‐ Job title: Dean of the college

3

NAME / STUDENT ID: ______________________________________________ GROUP: ______________________________________________

Photograph

4

CERTIFICATE

THIS IS TO CERTIFY THAT MISS/MR …………………………………… OF …………………………… HAS CARRIED OUT THE NECESSARY PRACTICAL WORK AS PRESCRIBED BY BATTER MEDICAL COLLEGE FOR SCIENCES AND TECHNOLOGY FOR THE YEAR …2010-201----

________________________________

INCHARGE

_______________________________________________ HEAD OF THE Biology DEPARTMENT

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Batterjee Medical College

FOUNDATION YEAR

Biology Practical Syllabus

Syllabus 2010-2011

Week Date

Experiments. Date Initials

Start End

Week 1 Blood Pressure measurement using

mercury sphygmomanometer.

Week 2 Slide preparation of human blood. Blood cell

count.

Week 3 Blood Types

Week 4

Haematocrit, packed red blood cells volume

Week 5

To determine your own bleeding time.

Week 6

To compare the amount of urea in three body fluid (urine, renal artery plasma, renal

vein plasma.

Week 7

Histology of cerebellum and spinal cord.

Week 8 Anatomy of cerebrum, model and specimen

(sheep brain)

Week 9

Revision quiz

Week 10

Check Point

,

Week

11 Sensory Anatomy

6

Model of eye

Specimen of sheep eye

Week 12

Physiology of endocrine gland (slide

slide)

Week 13

Stages of the mitosis in the root tip slide

Week 14

Gematogenesis

a. Slide of mammalian ovary. b. Slide of study of mammalian

testis.

Week 15

Basic techniques of microbiology.

Week 16

Lab Quiz

Revision

Week 17

Practical Exam Of

Final Term

7

Table of content

Serial No.

Content Page

1 Lab safety rules 1 -12

2 Blood pressure measurement 8-9

3 Preparation of blood smear 10-12

4 To determine your blood group 13-15

5 To determine the packed cell volume or hematocrit ratio

16-17

6 To determine your own bleeding time 18-19

7 To determine the difference in composition of urea in renal artery, plasma, renal vein and urine.

20-21

8 Microscopic structure of cerebellum and spinal cord

22-23

9 Lobes of cerebellum and there function. 24

10 To study the structure of eye ball and layers of retina.

25-26

11 Microscopic structure of thyroid gland 27-28

12 Stages of mitosis in root tip 29-31

13 Gematogenesis- microscopic slide of ovary and testes

32-34

Distribution of grades for Biology Practical

Semester % of marks

First Semester 1. Lab Activities (experiments) 2. Final practical exam

10% 5% 5%

Second semester 1. Lab Activities (experiments) 2. Final Practical exam

10% 5% 5%

Total Mark for One Academic Year 20%

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Date_________

Experiment (1) Blood Pressure Measurement

Introduction: Blood pressure or arterial blood pressure is the pressure (force per unit area) exerted by the blood on the walls of the blood vessels. The doctor measures the maximum pressure (systolic) and the lowest pressure (diastolic) made by the beating of the heart. The systolic pressure is the maximum pressure in an artery at the movement when the heart is beating and pumping blood through the body (ventricular contraction) The diastolic pressure is the minimum pressure in an artery in the moment between beats when the hearts is resting. Both the systolic and diastolic pressure measurements are important is either one is raised; it means you have high blood pressure (high hypertension). Arterial blood pressure is usually measured in millimeters of mercury (mmHg) using a sphygmomanometer.The average blood pressure for an adult is 120/80 mm Hg Objectives: To measure blood pressure by using mercury sphygmomanometer. To define blood pressure, and explain why blood exerts a pressure on the walls of blood vessels.

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Procedure:

1. A soft arm cuff is warped around the arm. A hand bulb pumps air into the cuff, gently squeezing the arm and temporarily interrupting the flow of blood in brachial artery. The pressure gauge reaches a peak (200mmHg).

2. Then the cuff is slowly deflated, letting blood flow again. As the cuff deflates

and the pressure gauge gradually decreases, the return of the blood flow through the main artery in your arm can be heard using a stethoscope.

3. The first time you hear the sound, note what the reading was on the pressure

gauge when the heart beat is first heard is your systolic pressure (the peak pressure as the heart contracts)

4. The reading when the pulse can first no longer be heard is your diastolic

pressure (the lowest pressure as the heart relaxes between beats). Post-Lab Question: 1. What is blood pressure? Ans:__________________________________________________________

______________________________________________________________

______________________________________________________________

2. What is high blood pressure (hypertension)? Ans:__________________________________________________________

______________________________________________________________

______________________________________________________________

3. How to measure blood pressure? Ans:__________________________________________________________

______________________________________________________________

______________________________________________________________

4. What causes high blood pressure?

Ans:__________________________________________________________

______________________________________________________________

10

Date_________

Experiment No: (2)

Preparation of Blood Smear Introduction. Much valuable information about the health of a patient can be obtained by a thorough and competent study of a smear of their peripheral blood. To prepare a blood smear, a drop of blood is spread on a glass slide and then stained. Wright's stain is widely used for staining blood smears. It contains eosin and methylene blue, both of which stain independently as well as in combination. Following are the different categories of blood cells.

ERYTHROCYTES (Red cells): The erythrocytes are the most numerous blood cells, have biconcave shape devoid of a nucleus. The red blood cells are rich in hemoglobin, a protein able to bind oxygen for providing oxygen to tissues

PLATELETS (thrombolytic): Platelets are fragments of megakaryocytic. Megakaryocytic are found in red bone marrow. The main function of platelets is to stop the loss of blood from wounds.

LEUKOCYTES (White cells): Leukocytes or white cells are responsible for the defense of the organism. In the blood, they are much less numerous than red cells. Leukocytes are divided in two categories: granulocytes and a granulocytes (lymphoid cells).Each type of leukocytes is present in the blood in different proportions:

Neutrophils 50-70%: Neutrophils are very active in phagocyting bacteria and are present in large amount in the pus of wounds. Unfortunately, these cells are not able to renew the lysosomes used in digesting microbes and dead after having phagocyted a few of them. Eosinophils 2-4%: Eosinophils attack parasites and phagocytes antigen-antibody complexes.

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Basophils 0-1%: Secrete anti-coagulant .Even if they have a phagocytory capability, their main function is secreting substances which mediate the hypersensitivity reaction.

Lymphocyte 20-40%: Lymphocytes may vary somewhat in size, but the majority of them will measure 7-8 μm (slightly larger than an erythrocyte). They have a relatively large, spherical nucleus. Lymphocytes yield antibodies and arrange them on their membrane. Monocytes 3-8%: The three most useful diagnostic features of these cells include their dull grey-blue cytoplasm, their larger size (12-15 μm), and their distinctive horseshge or kidney shaped nucleus.

Objective:

1. To determine red blood cells, white blood cells, and platelets are normal in appearance and number.

2. To distinguish between different types of white blood cells. 3. To determine their relative percentage in blood. 4. To help diagnose a range of deficiencies, diseases, and disorders

involving blood cell production. Materials:

1. Sterilized lancet 2. Clean microscope slide 3. Ethyle alcohol 4. Eosin 5. Methylene blue

Procedure:

1. Taking the Blood: Cleans a finger. With a sterile lancet, make a puncture on a fingertip. In the meantime, keep all the materials needed ready and protected from dust. The edge of another slide in contact with the drop and allow the drop to bank evenly behind the spreader.

2. Fixing: A fixing technique consists of dipping the smear in 95% ethyl alcohol for 3-5 minutes

3. Staining: To stain a smear, take a slide with a fixed and dry smear. Put on the slide a drop of stain until it is fully covered.

4. Observation: A magnification of 40 times is enough to observe and identify the different types of cells.

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Type of cells Size (diameter) No. in blood Erythrocytes 6—7.5 µm 4-6million/mm3

platelets 2---3 µm 200000-300000/mm3

Leukocytes 12---15µm 5000—7000mm3 Question:

1. What is Blood smear? Ans:________________________________________________________________________________________________________________________

1. Draw different types of blood cells as you see under the microscope,

and name them.

13

Date___________ Experiment: (3)

Blood Types

Introduction Human Blood is about 45% cell by volume, although it is only slightly thicker than water. Blood cells are suspended in a straw-colored fluid called plasma (about 55% of total blood volume). Plasma is mostly water but contains many dissolved substance, including gases, nutrients, wastes, ions, hormones, enzymes, antibodies and other proteins. On the surfaces of your red blood cells are one or more antigens that will cause their agglutination if exposed to the complementary antibodies. Agglutination is the clumping of erythrocytes. This could theoretically occur during blood transfusion. The transfusion of incompatible blood causes the destruction of donor erythrocytes and perhaps the death of the patient when clumping cells block blood vessels. For these reasons, blood used for transfusion is very carefully matched for compatibly with the patient’s blood. The Blood type you belong to depends on what you inherited from your parents.

ABO Blood Typing System

According to the ABO blood typing system there are four kinds of blood types: A, B, AB or O Blood Group A If you belong to the blood group A, you have A antigens on the surface of your red blood cells and B antibodies in your blood plasma. Blood group B If you belong to blood group B, you have B antigens on the surface area of your red blood cells and A antibodies in your blood plasma. Blood Group AB If you belong to blood group AB, you have A and B antigens on the surface of your red blood cells and no AB antibodies at all in your blood plasma. Blood Group O If you belong to blood group O, you have either A nor B antigens on the surface area of your red blood cells but you have both A and B antibodies in your blood plasma. Rh factor blood grouping system Many people have so called Rh factor on the red blood cell’s surface. This is also known as antigens and those who have it are called Rh+. Those who haven’t are called Rh-. A person with Rh- blood not have Rh antibodies naturally in the blood plasma. But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood without any problems.

14

ll. Objectives:

1. To find out your own blood group. 2. To observe Rh factor

lll. Materials: Sterlized lancet, clean glass slide, alcohol swab, antiserum A and B, antiserum D. lV. Procedure:

1. Clean a finger. 2. With a sterile lancet, make a puncture on a finger tip. 3. Place three small drops of blood on the slide. 4. Mix the blood with three different antiserum including either of three different

antibodies, A, B or Rh antibody. 5. Then you take a look at what has happened. In which mixture has agglutination

occurred?

Observation:

Anti Sera A Anti Sera B Anti Sera D

Observation table Note: Agglutination= +ve Agglutination= -ve

Antisera Antisera A&1drop 0f blood

AntisearB &1 drop of

blood

Antisera D &1 drop of

blood

My blood group is :

Agglutination

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_________

Who can

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Questions

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15

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16

Date____________ Experiment: (4)

To determine the packed-red cell volume or hematocrit ratio Introduction: The hematocrit, the volume of percentage of red cells in the whole blood, is determined by spinning a blood sample in a high-speed centrifuge for 2 to 5 minutes to separate the cellular elements from plasma. The hematocrit is expressed as the volume of packed red cells per unit volume of the whole blood for example hematocrit 38% in lab report means that the patient has 38 ml of red blood cells per 100 ml of blood, red blood cells comprise 38% of the total volume. For men 42% to 54%, for women 36% to 46%. To measure hemoglobin level, hemoglobin is released from red blood cells, and the color of blood is compared with known color scale. Objective:

1. Describe how to perform a hematocrit. 2. The student should be able to describe the conditions in which the ratio is altered

(decrease or increase).

Material: Hematocrit tube, centrifuge machine, sterilized lancet,alcohol swab.

Procedure: 1. Work in groups for four. Fill a plain capillary tube to the mark with aseptic or

simulated blood and seal it with clay. Fresh blood requires a capillary tube with the inside surface coated with a anticoagulant heparin to prevent clotting.

2. Place the sealed capillary tube in a microhematocrit centrifuge along with those from other groups.

3. After your instructor has secured and spun the tubes and open the centrifuge, recover your tube. Determine the percent red cell packed cell volume using a ruler.

4. Dispose of your capillary tube in the blood waste disposal jar.

Observation: Note: The percent packed volume of the red blood cells is calculated by dividing the height of the column of packed blood cells by the length of the total column and multiplying by hundred.

17

Result: The volume percentage of red blood cells in my blood is: _____________%.

Draw the capillary tube length and measure the packed-red blood cell volume using the ruler. Calculate the percentage volume.

18

Date____________

Experiment: (5) To determine your own bleeding time.

Introduction: Whenever there is a trauma, wound, cut or injury bleeding takes place. To prevent the excessive loss of blood, nature has provided the mechanism of Hemostasis that occurs in different steps. The first step is vasoconstriction which takes place on both sides of ruptured vessel up to several centimeters. The second step is the formation of platelet plug. As the vessels are traumatized, the nearby passing platelets come and adhere to the rough surface (collagen fiber) and secrete ADPs and thromboxan A2 which make these platelets sticky for each other passing platelets i.e platelet plug is formed which plugs the rent in the vessels. Sharply cut vessels bleed, more then the crushed vessels. The more a vessel is traumatized more is the degree of spasm. Platelet plug is unstable and temporary. Proper haemostasis occurs due to addition of clotting factor leading to formation of fibrin. Material: sterilized lancet, alcohol swab, filter paper, stop watch. Procedure:

1. After all usual precautionary measures, prick the finger with sterilized blood lancet about 3mm deep and start the stop watch.

2. Wipe off the blood from site. 3. Apply a gentle pressure and touch the site of prick with filter paper so that the spot

of the blood appears on the filter paper. 4. Repeat the procedure after every 30 second by touching the site of prick with the

filter paper and wiping it off every time till there is no spot of blood appears. Stop the stop watch.

5. Circle the spot of blood with pencil and note the time of each spot. 6. Note the bleeding time and paste the filter paper in your practical manual. 7. Bleeding time is also calculated by dividing the total number of drops on the filter

paper by 2.

Bleeding time = No. of drops on filter paper 2

19

Observation: Results: My bleeding time is ________ minute.

20

Date____________

EXPERIMENT NO. (6)

Difference In Composition 0f Urea In Renal Artery Plasma, Renal Vein Plasma and Urine.

INTRODUCTION: To compare the amount of urea in three different samples of artificial body fluid, the three artificial body fluids are plasma from the renal artery, plasma from the renal vein and urine. They are in test tubes labelled F1, F2 and F3 but not necessarily in that order. Urease is an enzyme that breaks down urea to produce ammonia.

Urea + Urease → Ammonia (NH3)

Material: 1. Test tubes. 2. Urea solution. 3. Urease enzyme. 4. Red litmus paper. 5. Bung (rubber stopper). 6. Pipette

PROCEDURE: 1. You are provided with a solution of urease enzyme. 2. Use the Pipette provided to add 3cm3 of urease to each test-tube. 3. Ammonia turns red litmus paper blue. 4. Moisten three pieces of litmus paper with water and place a piece of litmus paper in

each test-tube, such that it is trapped by the bung, as shown:

Detection of urea

Bung Damp Litmus Paper Solution (mixture of sample & Urease) 5. Start timing and record how long it takes for the litmus paper to being to change colour. If a colour change has not occurred within 10 minutes, record the time as infinity.

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OBSERVATIONS Record your results in the table below:

Test-tube

Time taken to being to change colour /min

F1

F2

F3

Q (1) State what colour the litmus paper turned in F1. ………………………………………………………………………………………………….. ……………………….…………………………………………………………………………. Q (2) For each solution, F1, F2 and F3, suggest which is urine, which is renal artery plasma and which is renal vein plasma. Explain your answer. F1 is……………………………………………………………………………………………. ………………………………………………………………………………………………….. F2 is…………………………………………………………………………………………… ………………………………………………………………………………………………… F3 is…………………………………………………………………………………………… …………………………………………………………………………………………………

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Experiment No: (7)

Microscopic structure of spinal cord Introduction: The spinal cord and brain makes the central nervous system (CNS). Put simply, their jobs is to coordinate nervous information so that the right impulses are sent to the right place at the right time. Observation: The purpose of this investigation is to examine section of the spinal cord and brain and related their microscopic structure of their overall function of coordination. Procedure: Before you at the spinal cord under the microscope it is useful to have the picture of generalized reflex arc in your mind (you figure). You will then know what to expect to find inside different region of the cord.

1. Examine a prepared transverse section of spinal cord under low or medium power. Identify the structure shown on the figure. Distinguish between the central grey matter and the peripheral white matter. The gray matter contains of cell bodies of numerous neurons, the white matter contain slender axon which transmit impulses in and out of spinal cord and axon which transmit impulses up and down the spinal cord to and from the brain.

2. Note the meninges surrounding and protecting the spinal cord; the outer and inner layer are separated by a delicate vascular middle layer.

3. Locate the cell body of an effector neuron in the ventral part of the grey matter in figure. Examine it under high microscope. Note in particular its slender branches (dendrites). These connect the other neuron. Look at a particular branch which may be axon. Extend your study of motor neuron by examining neuron in a prepared smear of spinal cord.

4. Label the layers of spinal cord.

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Microscopic Structureof cerebellum and spinal cord 

Introduction:

Cerebellum is a distinct part of the brain and its characterized by complex folding of cerebellum cortex, generating a pattern of pleats (cerebellar folia).the folia contains nuclei of nerve cels.

Under high power, cerebellum showing following layers:

1. The molecular layer: this layer is composed of nerve cells processes with scanty glial cells.

2. The granular layer: the bulk of small nerve cells with dark staining around nuclei. 3. White matter: below the granular layer is the white matter which contains myelinated

fibers. 4. Purkinge cells: charaterised by vast branching pattern of the dendrite in the

molecular layer, but this is only visible by the specific staining method.

Function of cerebellum:

The cerebellum controls fine movements by sending impulses down the axon of the purkinge cells.

Q. Label the microscopic structure of cerebellum

24

Date:_______________

Experiment (8) Lobes Of Cerebrum And Their Functions

Match the function of the cerebrum with their lobes Lobes Functions

A Parietal lobe ____ 1 Responsible for hearing and smelling

B Frontal lobe ____ 2 Responsible for vision

C Temporal lobe ____ 3 Responsible for sensation of temperature, touch, pressure and pain from skin.

D Occipital lobe ____ 4 Responsible for movement of voluntary skeletal muscles and elaboration of conscious thoughts.

25

Date:____________ Experiment: (9)

To Study The Structure Of Eye Ball And Layers Of Retina Introduction: Of all our senses, vision is the most developed. The retina contains photo receptors. You will discover that the eye is similar to a camera in structure in that our eyes use a lens to focus, and the retina is the “camera flim’’ our brain uses to ‘’make’’ images. Objectives:

1. Differentiate various structure of the eye ball. 2. See the retina and its important land marks 3. Know function of the lens.

Material: 1. Light microscope section of eye with retina and optic nerve. 2. Preserved sheep eye. 3. Dissecting scissors 4. Dissecting needle. 5. Forceps 6. Scalpel.

Procedure: 1. Obtain a preserved eye sheep eye and place it on a stalk of several paper towels.

Identify the external features. 2. Use dissecting scissors to dissect outer eye muscles and expose the tough, white,

fibrous connective tissues of the sclera. In life these muscles move the eye ball. 3. With a scalpel, make a incision about ¼ inch in black of and parallel to the edge of

the cornea into the interior cavity. Use scissors to extend the incision completely around the eye ball and gently pull the tow pieces apart. Identify the interal features of the eye ball.

4. Allow the lens and vitreous body of the posterior cavity to flow out of the posterior portion of the eye ball. Fill the posterior portion of the eye ball with water so as to flatten the retina for examination. Identify the blind spot.

5. Examine the lens and vitreous body.

26

Q1. On the basis of the above knowledge about the external and internal eye structure, label the following diagram.

27

Date:__________

EXPERIMENT NO. (10) Microscopic structure of the thyroid gland.

INTRODUCTION: The thyroid gland is situated in the neck close to the larynx. Its main function is to secrete the hormone thyroxine into the bloodstream. OBJECTIVE: The purpose of this investigation is to look at the thyroid under the microscope and relate its structure to its function. PROCEDURE: 1. Examine a section of thyroid gland under medium power and use it to help you interpret

its structure. Notice in particular numerous follicles, each surrounded by a single layer of cuboidal epithelial cells. The cavity (lumen) of each follicle contains a substance, thyroglobulin, which takes up stains and is usually visible in sections.

2. Consider the following information on how the gland works. The follicle cells absorb

iodide and other metabolites from the bloodstream. They synthesis thyroglobulin from these raw materials and secrete it into the lumen of the follicle for temporary storage. When required, they absorb thyroglobulin from the lumen and convert it into thyroxine, which is then secreted into the blood.

An Epithelial cell in the wall of a thyroid Part of thyroid gland under microscope. Follicle with an adjoining capillary

28

On the basis of the above knowledge about thyroid gland fill the following blanks:

1. The thyroid gland in composed of numerous _______________. 2. Each follicle consists of a single layer of _____________ cells. 3. Single layer of epithelial cells surrounding the cavity of follicle called

________________. 4. The lumen of follicle is filled by ___________. . 5. The colloid which is the store of large glycoprotein known as__________. 6. Lysosomes degrade thyroglobulin to produce small hormone molecule that are

released into the ________________.

Questions: Q1. Write two precursors (raw material) of thryoglubulin that enter a thyroid epithelial cells. Ans.___________________________________________________________________

______________________________________________________________________

______________________________________________________________________

Q2. Name two hormone molecule that thyroid gland releases into the blood. Ans.___________________________________________________________________

______________________________________________________________________

______________________________________________________________________

Q3. What is collide? Ans.___________________________________________________________________

______________________________________________________________________

______________________________________________________________________

Q5. State two advantages of storing the hormone molecules as thyroglobulin.

Ans.___________________________________________________________________

______________________________________________________________________

______________________________________________________________________

29

Date:__________ Experiment No. (11)

Stages of Mitosis in Root Tip

Introduction: Mitosis, also called karyokinesis, is division of the nucleus and its chromosomes. It is followed by division of the cytoplasm known as cytokinesis. Both mitosis and cytokinesis are parts of the life of a cell called the Cell Cycle. Most of the life of a cell is spent in a non-dividing phase called Interphase. Interphase includes G1 stage in which the newly divided cells grow in size, S stage in which the number of chromosomes is doubled and appear as chromatin, and G2 stage where the cell makes the enzymes & other cellular materials needed for mitosis. Mitosis has 4 major stages --- Prophase, Metaphase, Anaphase, and Telophase. When a living organism needs new cells to repair damage, grow, or just maintain its condition, cells undergo mitosis. During Prophase, the DNA and proteins start to condense. The two centrioles move toward the opposite end of the cell in animals or microtubules are assembled in plants to form a spindle. The nuclear envelope and nucleolus also start to break up.

Prophase

During Metaphase, the spindle apparatus attaches to sister chromatids of each chromosome. All the chromosomes are line up at the equator of the spindle. They are now in their most tightly condensed form.

.. Metaphase

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During Anaphase, the spindle fibers attached to the two sister chromatids of each chromosome contract and separate chromosomes which move to opposite poles of the cell.

Anaphase

In Telophase, as the 2 new cells pinch in half (animal cells) or a cell plate forms (plant cells), the chromosomes become less condensed again and reappear as chromatin. New membrane forms nuclear envelopes and the nucleolus is reformed.

Telophase

Objective:

1. .To recognize changes in chromosomes and other nuclear materials during mitosis.

2. You may use your textbook and class notes to help you identify the stages of mitosis as seen under the microscope.

Materials:

Microscope, prepared slide onion root tip,lab worksheet, pencil

Procedure:

1. Set up a compound light microscope and turn on the light. 2. Place a slide containing a stained preparation of the onion root tip 3. Locate the meristematic or growth zone, which is just above the root cap

at the very end of the tip or

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4. Focus in on low power, and then switch to medium or high power. Below find micrographs of the four stages of mitosis. Use them to help you identify the stages on the microscope slide.

Q1. The photomicrograph shows cells dividing by mitosis in a longitudinal section of a root tip.

Look at the cells labelled 1, 2, 3, 4, and 5.

Q1. Name the stage of mitosis for each numbered cell. 1 __________________________

2 __________________________

3 __________________________

4 __________________________

5 __________________________

Q2. List the cell numbers in the correct sequence for the stages of mitosis.

______ ______

______ ______ ______

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Date:____________ Experiment No: (12)

Gametogenesis

Introduction

Gamete formation (gametogenesis) is called oogenesis in the female and spermatogenesis in the male. Here we examine the gamete formation in the gonads of mammals. The gonads are paired organs and are called testes in male and ovaries in female.

Materials:

1. Microscope 2. Prepared slides of a section of

a. Adult mammalian testis b. Adult mammalian ovary with follicles c. Adult mammalian ovary with a corpus luteum

Procedure and Observations:

(A) Mammalian spermatogenesis: 1. With your microscope, look at the prepared slide of the testis. Most of the

interior of a testis is filled with coiled seminiferous tubules, which coil. Transverse and oblique section are present in your slide. Look for glandular interstitial cells between the seminiferous tubules. Interstitial cells secrete the male sex hormone testerone.

2. Center a cross section seminiferous tubules in the field of view and increase the magnification until you see only a portion of the tubule’s wall. In the wall of seminiferous tubule, identify as many stages of spermatogenesis as possible, as well as Sertoli cells, which function to nurture the development of sperm.

Spermatogenesis in most animal species is seasonal, its completion coinciding with mating. In humans, however, sperm production is continuous from puberty throughout the male’s lifetime.

33

On the basis of above knowledge label the diagram of testes below:

Label the name for

A:______________

B: _______________

C:_____________

(B) Mammalian oogenesis: 1. With the microscope, examine a prepared slide of a section of

mammalian ovary. Look for primordial follicles. Both the follicles and their primary oocytes. Groups of primordial follicles tend to occur between maturing follicles or between maturing follicles and the ovarian wall. Note the wall of the primordial follicle is composed of single layer of smaller cells.

2. Now look for the maturing follicles. In maturing follicles, the size of the cells and in the follicle wall and of the primary oocyte its self increases. Also, the follicle cells divide, causing the wall to become first two cells thick and then multilayered. Then a space appears between the follicles cells. This fluid-filled space increases in size until the primary oocyte and the follicle cells immediately around the primary oocyte are suspended in it. The mass of the cells in connected to the rest of the wall by a narrow stalk of follicles cells. Just prior to ovulation, the follicle reaches its maximum size and bulges from the surface of the ovary.

3. Replace the slide on the microscope with one of the mammalian ovary with a corpus luteum. Locate a corpus luteum.

A

B C

lutecor

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34

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