Easy tips for microscope handling

How to use a compound microscope

Know your microscope : know the all part of microscope and their use. Repeat these things until you become familiar.

Move the microscope carefully:

1.     use your both hand , one arm place at arm of microscope and another hand place base of microscope .

2.     hold the microscope close to your body as far as possible.

3.     Put the microscope away from the edge of table

How to focus a histological slide without breaking

1.     Put the slide on the stage and secure by stage clips

2.     At 1^st you use low power lens ×4, just for scanning the slide

3.     Lower the condenser lens

4.     Turn on the light (Illuminator)

5.     Observe where the tissue present in the slide

6.     By moving stage adjustment node you place the tissue at the centre of light seeing from outside ( not adjust this things by placing your eye at optical lens , it kill your time)

7.     Now from outside your lower the objective lens, then place your eye at optical lens and move the objective lens upward

8.     Never lower the objective lens when your eyes are at the optical lens . if you follow this rules you never able to break a slide

Tips for better focusing :

1.     When you use ×4 objective lens , condenser lens should at lower most position and diaphragm should widely open

2.     When you use ×10 objective lens, you move the condenser lens upward and diaphragm should close little bit

3.     When you use ×40 objective lens, you move the condenser lens upward and diaphragm should close little bit

4.     When  you use ×100 objective lens, give oil on the slide and lower the objective lens until it touch the slide , you move the condenser lens upward until it touch the slide and diaphragm should close little more

5.     Before observing the slide one should use the fine adjustment knob , because vision varies person to person

Tips for easy handling of microscope when you observing slide by placing your eye on optical lens

1.     Sit down

2.     After focusing the slide place one hand on fine adjustment knob and another hand on the stage adjustment knob ,

3.     Only these two location you need to handle for  observing  the slide

4.     If you needed to focus the slide again or needed to lower the objective lens you should not place your eye at optical lens at that time , you must see outside and observe until the objective lens touch the slide , than place the eyes on optical lens and move objective lens upward

5.     If the microscope is binocular then adjust the eye pieces according to the distance of your both eye , if the microscope is uniocular then one eye place to eye piece and another one keep open ( don’t close one eye)

Tips for using stage adjustment knob:

                      In microscope you using multiple lens , so you should remember following rules before moving

                       the slide

1.     If you want to move the slide upward you must move the slide downward

2.     If you want to move the slide right you must move the knob to the left and vice versa  

Maintain your microscope :

1. After use turn off the light
2. Remove the slide
3. Change the objective lens to lower power
4. Lower the condenser lens
5. Don’t touch the lens
6. Clean lens by lens paper or lilen cloth
7. Cover the microscope
8. Place the microscope in a dust free location
9. Use silicon in the box of microscope for lowering moistures
   
   

spleen secondary lymphatic organ : important highlights

Spleen: It is the largest accumulation of lymphoid tissue in the body.

Function:

i)                    Removal of old red blood cells

ii)                  Immune response

iii)                Reservoir of blood

iv)                 Formation of erythrocyte in fetal life

Histological features of spleen:

i)                    Splenic pulp: white and red pulp is present

ii)                  Capsule is present (covers the spleen, )

Trabeculae arises from capsule divide spleen into incomplete compartment  

White pulp: contain

Lymphatic nodules with germinal centers,

A central arteriole

Periarterial lymphatic sheaths (surround the central arteriole,  contain T lymphocytes)

SN: Central arteriole and periarterial lymphatic sheath situated within the lymphatic nodules

Red pulp:It is formed by splenic cord and splenic sinusoid

Splenic cord contains

T & B Lymphocytes,

Reticular cells & fibers,

Macrophages, Plasma cells,

Many blood cells-Erythrocytes,Platelets, Granulocytes

Splenic sinusoids: is formed by Discontinuous endothelial cells lining with discontinous  basal lamina

Splenic circulation

Closed circulation:

Splenic artery →the trabecular artery →central artery →penicillar arteries→ terminal  arterial capillaries (TAC) →splenic sinusoids →splenic vein

Open circulation:

Splenic artery →the trabecular artery →central artery →penicillar arteries→terminal  arterial capillaries (TAC) →red pulp →splenic sinusoids →splenic vein

Lymph node : easy and brief description

Lymph node

Lymph nodes are small encapsulated organs located along the pathway of lymphatic vessels   

Diameter: 1mm to 2 cm

Two types of lymphatic vessels are connected with lymph node: they are –

1. Afferent lymph vessels: convey lymph toward the L. node and penetrate the capsule at multiple sites.  

2. Efferent lymph vessels: convey lymph away from the lymph node and leave at the hilum. It is one in number.

 Functions of lymph node:

1. Filter the lymph
2. 2.Produce lymphocytes
3. 3. Initiation of immune responses
4. 4.phagocytosis

Histological features of Lymph node:

1. capsule is present
2. sub-capsular sinus is present
3. Outer cortex contains lymphatic nodules. Superficial part of cortex contain B lymphocytes and deeper zone of cortex contain T lymphocyte
4. inner medulla  contain medullary cord which composed of B lymphocyte and plasma cells  

Cells present within the lymph nodes:

1.T & B lymphocyte,

2.dendritic cells,

3.macrophages

What is lymphatic nodule?

Ans: small collection of lymphocytes found in mucosa of different organs like ileum, appendix, bronchus etc.

Types of lymphatic nodule:

Primary and secondary lymphatic nodules

When a germinal center appears in a lymphatic nodule the lymphatic nodule known as secondary L nodule

What is germinal center:

It is a pale staining area situated within a lymphatic nodule contain immature B lymphoblast.

Germinal centre found only in secondary lymphatic nodule.

What is trabeculea?

Ans: They are the part of capsule which enter in to the organ

What do you mean by sinuses of lymph node?

Ans: these are empty spaces within a lymph node where lymph flows. 

Thymus : brief and easy handout

Type of organ: lympho-epithelial organ

Location:  in the superior mediastinum.  

Parts: It has two lobes

Cells of thymus:

i) Developing T lymphocytes (which come from bone marrow lymphoid stem cells) 

 ii) epithelioreticular cells

Development:

    i) Lymphocyte: mesodermal in origin

    ii) Epithelium primordium : developed from the endoderm of 3rd and 4th pharyngeal pouches.

Thymus function:

Maturation and differentiation of T lymphocytes so they can distinguish between self antigen and non-self antigen.

Histological features of thymus :

a) Capsule is present which penetrate and divides the thymus into incomplete lobules.

b) Each lobulus is divided into outer cortex and inner medulla

c) Outer cortex of each lobules contain large number of developing T lymphocytes

    but contain no lymphatic nodule

d) Medulla  contain Hassall’s corpuscles which are formed by epithelio-reticular cells
 Thymic or Hassall’s corpuscles

•          Location: thymic medulla.

•          Formation: by epithelioreticular cells. The epithelioreticular cells are concentrically arranged and cytoplasm of the cells contain keratohyalin granules, lipid droplet and intermediate filaments

Blood thymic barrier

1.Lining endothelium of the capillary  wall

2.Basal lamina of endothelial cells

3.Macrophages in the surrounding  perivascular connective tissue

4. Basal lamina of epithelioreticular    cells

5.Epithelioreticular cells

Important of blood thymic barrier:

Prevent entering of antigen into the thymic cortex

Two important negative points regarding Thymus:

It contain

i)  No lymphatic nodules and

ii) No B lymphocytes

 Involution of the thymus:  After puberty much of the parenchyma of the thymus, in particular cortical lymphoid tissue, is replaced by adipose tissue.

Cells of lymphatic or immune system, development to final destination :summary

Cells of lymphatic or immune system:

1. Different types of lymphocyte: a)T lymphocyte :are four types   i) helper T cells ii) Cytotoxic T cells iii) Suppressor T cell iv) Memory T cell b) B lymphocyte: produce plasma cells which secrete antibodies         c) Natural killer cells  (Helper T lymphocyte stimulate the development of other lymphocytes so it is known as master lymphocyte,in HIV this cell is destroy by HIV virus, so other cells of immune system became inactive)

2. Antigen presenting cells: a) Macrophages  b) Kupffer cells of the liver  c)Langerhan’s cells in the epidermis d) Dendritic cells of spleen and lymph nodes

Development of Lymphocyte

Lymphocyte	Origin	Maturation and differentiation	Final destination
T lymphocyte	Bone marrow	Thymus	Mid & deep zone of lymph node, In periarterial lymphatic sheath of spleen, mucosa associate lymphatic tissue
B lymphocyte	Bone marrow	Bone marrow	superficial zone of lymph node, outside the periarterial lymphatic sheath of white pulp of spleen, mucosa associate lymphatic tissue

Lymphatic drainage of body : easy description

Lymphatic drainage of body

What is Lymph?

Ans : Tissue fluid which came out from capillary and enters in the lymphatic capillary is known as lymph.

They contain macromolecules of colloid like protein, carbondioxide, cancer cells, bacteria etc.

Cisterna chili: it is a dilated lymphatic sac situated in front of L1-2. Collect lymph from abdomino-pelvic organs. It is continued above as thoracic duct

Lymph vessels	Collect lymph	Drain lymph into the	Number
Lymph capillary: they begin blindly in the tissue space around the blood capillaries	LC collect lymph from tissue space	Afferent lymph vessels	Many
Afferent lymph vessels	Collect lymph from lymph capillary	Adjacent lymph node	Many & located around  the capsule of lymph node
Efferent lymph vessels	Collect lymph from lymph node	Drain lymph into terminal lymphatic ducts	One in number, exit  lymph node through in hilum
Terminal lymphatic duct : two in number
i) right lymphatic duct	Collect lymph from right side of head and neck, right upper limb & chest	Drain lymph into the venous system at the junction between right  internal jugular vein and rt subclavian vein
ii) thoracic duct	Collect lymph from whole body except right side of head and neck, right upper limb & chest	Drain lymph into the venous system at the junction between left internal jugular vein and left subclavian vein

Component of lymphatic system

Lymphatic system :

Component of lymphatic system : 

1. lymph vessels:

• lymphatic capillary,
• afferent & efferent lymph vessels,
• thoracic duct,
• right lymphatic duct

2. Lymphatic organs:

Primary lymphatic organs :

• bone marrow
• thymus

Secondary lymphatic organs :

• spleen,
• tonsil,
• lymph nodes,
• mucosa associated lymphatic tissue:

               BALT : bronchus associated lymphatic tissue ,

               GALT: gut associated lymphatic tissue

Lymphatic capillary : 

it has some unique character

1.  overlapping of endothelium
2. discontinuous basal lamina
3. anchoring filaments (elatic fibres) attach the endothelium with surrounding tissue 

Due to these features interstitial fluid enter in to lymphatic capillary like one way gate

Why bone marrow and thymus consider as primary lymphatic organ?

Ans: In these organs, the cells of immune system became mature and differentiate so they are known as primary lymphatic organ.

After maturation and differentiation an immune cells (lymphocyte) can distinguish between self antigen and non-self antigen. So a mature lymphocyte destroy non-self antigen but not react with self antigen.

What is the function of secondary lymphatic organs?

Ans : They only proliferate the cells of immune system ( lymphocytes)  but maturation and differentiation is not possible in secondary lymphatic organ