XII. 



ADIPOSE TISSUE. 



171 



turpentine or xylol, which dissolves out the paraffin ; the section is 

 afterwards mounted in balsam. 



(L) Observe the very vascular small lobules, composed of fat-cells. 

 To each lobule there passes one artery, and from it emerge one or 

 two veins. 



(H) Observe the loop of capillaries round each fat-cell or around 

 several fat-cells. 



7. Development of Fat-Cells. These may be studied in the 

 subcutaneous tisyie of a newly-born rat, or in the omentum of a 

 newly-born rabbit. Stain a small 



piece of any of these tissues in osmic 

 acid. 



(a.) (L) Observe the fat-cells in 

 groups surrounded by connective 

 tissue. 



(b.) (H) Observe the shape of the 

 cells, with small globules of oil 

 black scattered throughout the 

 protoplasm, the nucleus pushed to 

 one side in the more developed fatty 

 cells by a globule of oil, which is 

 stained black (figs. 138, 141). 



8. Atrophic Fat-Cells. These are 

 readily obtained from the yellow 



bone-marrow of an old person who has died from some wasting 

 disease, or from the sub-pericardial fat of a person who has died 

 from phthisis. 



(H) Observe the envelope of the fat-cell, now no longer completely 

 filled with fat, but containing a little protoplasm and some serous 

 fluid. 



9. Injection Method. By means of a hypodermic syringe, inject 

 under the skin of a dog or cat silver nitrate (i in 1000), which 

 c.-iuscs a local oedema and isolates the elements of the areolar tissue, 

 including the fat-cells (JRanvur). 



FIG. 141. Developing Fat-Cells from 

 the Subcutaneous Tissue of a 

 Foetus. Osmic acid. 



MUCOUS TISSUE. 



Mucous Tissue. In the embryo it exists under the skin ; it 

 forms Wharton's jelly of the umbilical cord, and in the, adult it forms 

 the. vitreous humour. It is essentially an embryonic tissue. 



10. Mucous Tissue (H). Harden the umbilical cord of a three- 

 inonths foetus in Mailer's fluid and then in alcohol. J\ lake trans- 

 verse sections by freezing, and stain them in picro-cannine or 

 h;eni;itoxvlin or gentian-violet. Mount in Warrant's solution. 



(a.) Observe the large, branched, granular, nucleated cells, which 



