Histological sampling of fish

Lesson 13

1. Read the words and put down their Russian equivalents:

vital

diagnosis

sampling of tissues

pathology

behavioral abnormalities

sacrifice

irritant

post-mortem changes

formaldehyde

2. Master the active vocabulary:

histopathology - патологическая гистология, гистопатология

lesion - повреждение, поражение (органа, ткани);

moribund - умирающий; заканчивающийся

spleen - селезенка

pancreas - поджелудочная железа

fry - мелкая рыбешка; мальки

3. Read and translate the text:

Histology encompasses the scientific area concerned with the structure of tissues and histopathology the relevant branch of pathology. Histopathology can therefore provide information on the processes and changes occurring in tissues and in many cases form the basis for disease diagnosis and prognosis. Accurate sampling of tissues for histology is a vital part in the diagnostic procedure and to follow are guidelines for on site sampling. Before sampling any fish note any behavioral abnormalities or visible external lesions.

1) As with other diagnostic procedures, a mixture of sick (moribund) and healthy fish should be sampled. Dead fish (recent mortalities) provide little accurate information and are virtually useless for histology.

2) Sacrifice the chosen fish by stunning the fish by a blow to the head or through anaesthesia.

3) Phosphate buffered formalin is the tissue fixative of choice for the majority of samples. 10% formalin is the usual concentration (formalin being 40% formaldehyde). Care should be taken as formalin is an irritant, especially to eyes.

4) Following killing of the fish, samples should be immersed in formalin as quickly as possible (all tissues should be sampled within five minutes of killing) as post-mortem changes will occur rapidly in these cold blooded animals.

5) Remove a small piece of tissue (<1cm2) from the organs and include any areas showing gross abnormalities.

6) Sample gill, heart, spleen, liver, pyloric caecae/pancreas, kidney, section of skin and muscle (at lateral line) and brain. Small fish or fry may be sampled whole with the abdomen opened to allow proper fixation of the internal organs.

7) Ensure amount of formalin in pot is approximately 10 times the amount of tissue.

8) Record any details about fish on paper e.g. body condition, weight, length, feeding, internal appearance, etc...

9) Label the sampling pot with a water proof marker and ensure that each pot will not leak.

10) Dispatch/deliver samples with relevant details and clinical history and contact the diagnostic service by telephone or fax.

Phosphate Buffered Formalin Solution (PBFS)

Formula: Formaldehyde (40%) 100ml

Water (tap OK if distilled unavailable) 900ml

disodium hydrogen orthophosphate 6g

sodium dihydrogen orthophosphate 5.5g

Dissolve dry powder in water, and then add formaldehyde.

4. Answer the following questions:

1. What is histology?

2. Why should a mixture of sick and healthy fish be sampled?

3. May small fish be sampled whole with the abdomen opened?

4. What is the proper proportion of fish and formalin?

5. Should you label the sampling pot? Why?

5. Change the words according to the model. Translate the words.

Model: translation, to translate – переводить

Preparation, to _______________ - ____________________________

Introduction, to ______________ - ____________________________

Fixation, to _________________ - ____________________________

Population, to _______________ - ____________________________

Concentration, to _____________ - ____________________________

6. Which of the following words are nouns? verbs? adjectives? adverbs? Why?

Phosphate, usual, buffered, formalin, tissue, fixative, choice, majority, samples, gross, abnormalities, relevant, branch, skin, muscle, diagnostic, service, leak, pyloric.

7. Insert the words into the following sentences.

1. Dead fish provide little … information and are virtually useless for histology.

2. Remove a small piece of … from the organs.

3. Label the … pot with a water proof marker and ensure that each pot will not leak.

4. Before sampling any fish note any behavioral … or visible external lesions.

5. Small fish or fry may be sampled whole with the … opened to allow proper fixation of the internal organs.

(abnormalities, abdomen, accurate, sampling, tissue)

Дата добавления: 2014-12-26