SKIN 



226 



SMEARS 



G., Anat. Rec, 1934, 60, 493-499. See 

 Sebaceous and Tarsal glands, Hairs, 

 Nails, Feathers. 



If it is not desired to investigate a 

 particular area, to which attention has 

 been called by its unusual gross appear- 

 ance ; but, instead, to demonstrate some 

 special component, or response, of the 

 skin one should be guided in selection 

 of the specimen by the location where 

 the component or response is most likely 

 to- be found. Thus Meissner's corpuscles 

 are best seen in sections of skin of 

 palmar surface of finger tips. Weddel, 

 G., J. Anat., 1941, 75 (3), 346-367 reports 

 that multiple groups of Krause's end- 

 bulbs occur beneath each cold spot in the 

 forearm about 1 mm. inward from the 

 skin surface. Many helpful clues are 

 supplied by Lewis, T., Pain. New 

 York: MacMillan, 1942, 192 pp. He 

 quotes Strughold as stating that pain 

 spots are aggregated as closely as 200 

 per sq. cm. in supraclavicular, ante- 

 cubital, inguinal and popliteal fossae 

 while they are rare (40-70 per sq. cm.) 

 on tip of nose and ear, soles and palms 

 (see Nerve Endings). The skin of 

 axillary, pubic and nipple areas is more 

 likely than that of the rest of the body 

 to respond to sex hormones. Adjust- 

 ments to external environment are to be 

 expected in exposed parts. To search 

 for sweat glands in those mammals which 

 do not possess any is futile. To expect 

 all epidermal layers in thin epidermis is 

 likewise contraindicated. 



Fluorescence Microscopy is capable 

 of yielding interesting results in dis- 

 tinction between psoriasis and hyper- 

 keratosis scales (Radley, J. A. and 

 Grant, J., Fluorescence Analysis in Ul- 

 traviolet Light. New York: Van Nos- 

 trand, 1935). Further indications on 

 fluorescence are given under Hair and 

 Sebaceous Glands. 



Now that epidermis can be conven- 

 iently separated from dermis it is desir- 

 able to give details of technique relating 

 to it under a separate heading. See 

 Epidermis. 



Skunk's Stain, see Flagella. 



Skyblue (CI, 1286)— coelestin blue, coeline, 

 coeruleum — a mineral pigment, cobal- 

 tous stannate, seldom used in medical 

 research. 



Slides, see Cleaning. 



Slifer-King method, see Ticks. 



Slime Forming Bacteria, Conn's method. 

 Stain for about 1 min. with a little heat 

 in Rose bengal 1 gm., 5% aq. phenol 

 100 cc, 1% aq. CaCh, 1 cc; then wash 

 quickly and dry (McClung, p. 146). 



Small Intestine. Many conditions influence 

 the appearance seen in sections. If 

 fixed while distended with food rnate- 

 rial, the spaces between the villi are 

 more noticeable, the villi shorter and 



the muscular layers thinner than when 

 fixed while strongly contracted. See 

 illustrations provided by Johnson, F. 

 P., Am. J. Anat., 1912-13, 14, 235-250 

 and Contraction Bands. The time after 

 feeding and the character of the food has 

 a marked influence on structure. The 

 cytoplasmic granules of the Paneth 

 Cells are almost all discharged in guinea 

 pigs 6 hrs. after feeding. They are pres- 

 ent in large numbers after fasting for 24 

 hrs. (Klein, S., Am. J. Anat., 1905-06, 

 5,315-330). Even vitamin B deficiency 

 alters the distribution of intraepithelial 

 fat (Mottram, J. C, Cramer, W., and 

 Drew, A. H., Brit. J. Exp. Path., 1922, 

 3, 179-181). According to Hamperl 

 (H., Ztschr. f. Mikr.-Anat. Forsch., 

 1925, 2, 506-535) Enterochromaffin Cells 

 can no longer be found in humans autop- 

 sied as late as 4-5 hrs. after death. The 

 incidence of Contraction Bands in 

 muscle is increased by exposure to air 

 and mechanical manipulation before 

 fixation. Villi are very prone to ex- 

 hibit Agonal Changes. If the indi- 

 vidual has fasted for a long time before 

 death a marked invasion of the mucous 

 membrane by lymphocytes is to be ex- 

 pected. See Fig. 158, Cowdry's His- 

 tology. It may extend throughout the 

 gastrointestinal tract being greatest in 

 the stomach and least in the large in- 

 testine. 



A good way to examine the wall of the 

 small intestine is to push a test tube of 

 appropriate size into the lumen of a 

 segment. This will hold it open and 

 facilitate dissection. Strip off the 

 serosa, then the tunica muscularis, not- 

 ing the direction of the fibers and leaving 

 only the mucosa. Take small pieces of 

 mucosa and mount in physiological 

 saline inside up and e.xamine at low 

 magnification. Finally with dissecting 

 needles pick out separate villi and study 

 with oil immersion objective. To ob- 

 tain a clearer concept of individual 

 muscle fibers first macerate the intestine 

 on the tube in 15% aq. nitric acid for 

 2-3 days. Consult Carey, E. J., Anat. 

 Rec, 1921, 21, 189-215 and Goerttler, 

 K., Morph. Jahrb., 1932, 69, 329. See 

 Chloralhydrate Maceration. 

 Smears. To examine fluids and tissues as 

 thin films so that the components are 

 individually clearly visible is often nec- 

 essary. Careful preliminary cleaning 

 of the slides is necessary. Touch the 

 surface of a slide about 2 cm. distant 

 from the end to a drop of blood imme- 

 diately on the appearance of the latter 

 from a puncture in the skin. Quickly 

 apply the smooth end of another slide 

 to the drop and the surface of the first 

 slide so that the drop spreads along the 

 line of contact. Then evenly push the 

 second slide, with the blood following it, 



