328 



CYTOCHEMICAL TESTS ON EMBRYOS 



Fix the tissues in 95% alcohol, embed and section in the usual manner, and stain in 

 the above (Unna's) stain for 20 minutes. 



The albumins and globulins are stained red by the pyronine, while the nucleo-proteins 

 are stained blue-green with the methyl green. To separate the albumins and globu- 

 lins one can take advantage of the differential solubility. The albumins and pseudo- 

 globulins are soluble in water, the globulins are not soluble in water. Both are 

 soluble in salt solutions. Failure to stain with methyl green would indicate the 

 absence of nucleoproteins. 



O H 

 O H 0(P03H2) II N 



OH ^ N . /^^ -^^ OH 



N 



OH 



N 



H^N 



O 



N 



0{P03H2) 



N 



O 



Guanin - d - rjbose nucleotid 

 (Ribosnucleic acid) 



Guanin - 2-desoxy - d - ribose - 

 nucleotid (Thymonucleic acid) 



The distribution of ribonucleic acid at 

 tliree stages in the oogenesis of the 

 amphibian egg. (Redrawn from Brachet, 

 1944.) 



Azure A-Phthalate (Pollisler ) 



Fix tissue in Carnoy's 10 min. , wash once in 50% alcohol. 

 Immerse in Azure sol. (Pollister) - 2 hrs. 

 Flood slide with tertiary butyl alcohol in glycerine. 

 Differentiates between nucleic acids. 



Methyl Green-Py ronin Y Method tor Nucleic Acids * 



1. Paraffin Method 



a. Fixation: Absolute methyl alcohol 24 hrs. 



Change once soon after fixation, using small 

 pieces of tissue 2-3 mm thick. 



b. Dehydration: Absolute n-Butyl alcohol 30 min. 



Absolute n-Butyl alcohol change 30 min. 



c. Embedding: Alcohol-paraffin mixture in oven at 56°C 1 hr. 



Mixture: 50% n-Butyl alcohol + 50% melted paraffin. 

 Oven temp, must not exceed 56°C. at any time. 



Pure paraffin, 4 changes during 2 hrs. 



Embed. 



* Courtesy Dr. M. ¥.. long, from Long G Taylor, 1956. 



