DIRECTIONS FOB LABORATORY WORK 775 



perichondrium (articular, costal, tracheal or bronchial). Sketch (72) 

 narrow segment of entire plate. Make h.p. drawing (73) of (TT) -peri- 

 chondrium and (b) central portion of plate. Note carefully transition 

 from perichondrium to cartilage ; cell groups, lacuna, capsule and hyaline 

 matrix. Are blood vessels, lymph vessels or nerves discernible in the 

 matrix? The fetal precursor of the majority of bones is also hyaline 

 cartilage. What is the fundamental structure of the hyaline matrix? 



(2) ELASTIC CARTILAGE (Yellow fibro-cartilage). Study car- 

 tilage plate of the epiglottis or the external ear (e.g., ox) in stained 

 section. Note elastic fibers in the hyaline matrix. (Some specific elas- 

 tic tissue stain should have been employed with the section.) Sketch 

 (74) a segment from perichondrium to center inclusive. 



(3) FIBRO-CARTILAGE (White fibro-cartilage). Study a stained 

 section of an intervertebral disc (e.g., ox) or the semilunar car- 

 tilage of the knee. Is a perichondrium present? Note the collagen 

 fibers in the matrix (a specific collagen fiber stain should be employed, 

 e.g., Mallory's or Van Gieson's). How does fibro-cartilage differ from 

 hyaline cartilage and from tendon? Sketch (75) a small area of central 

 portion of cartilage disc. Structural differences between intervertebral 

 disc and semilunar cartilage of knee? 



(4) PRECARTILAGE. Sketch (76) a small area of the condensed 

 mesenchyma in the region of a future bone in a transverse stained sec- 

 tion of some mammalian embryo, e.g., pig of 10 to 15 mm. 



(5) VESICULAR SUPPORTING TISSUE. A variety of connective tis- 

 sue found in the sesamoid bone of the tendon of Achilles of 

 the frog, characterized by abundant large clear cells scattered among 

 bundles of collagen fibrils, is somewhat similar to mammalian fibro-carti- 

 lage, and represents a transition from dense connective tissues to carti- 

 lage. Study a section of the tendon of Achilles of the frog. Note dif- 

 ferences and similarities between this tissue and mammalian tendon and 

 fibro-cartilage. Sketch small area. 



(b) Bone (Osseous tissue). 



(1) GROSS STUDY. Study macroscopically and with hand lens a 

 longitudinally cut long bone (e.g., femur). Note: central marrow cav- 

 ity, peripheral compact bone of diaphysis, and terminal cancellous bone 

 of epiphyses. Note also jagged border of marrow cavity terminally. 



(2) MACERATED COMPACT BONE (ground section of bone). Study 

 l.p. a transverse section through the diaphysis. Note: central mar- 

 row cavity, outer circumferential (periosteal) lamellae; inner circum- 

 ferential (endosteal) lamellae; interstitial lamellae; Haversian systems 



