Fibroblasts are the primary cells responsible for secreting collagen and elastin fibers in connective tissues.
Cartilage, Bone, Adipose tissue, and Areolar tissue: All contain fibroblasts or related cell types (chondrocytes in cartilage, osteoblasts in bone, adipocytes in adipose tissue) that produce collagen or elastin fibers.
Blood: Blood does not contain fibroblasts. Its matrix (plasma) contains various proteins, but these are not secreted by blood cells in the same way that fibroblasts secrete collagen and elastin.
| List - I | List – II | ||
| A. | Squamous Epithelium | i. | Goblet cells of alimentary canal |
| B. | Ciliated Epithelium | ii. | Inner lining of pancreatic ducts |
| C. | Glandular Epithelium | iii. | Walls of blood vessels |
| D. | Compound Epithelium | iv. | Inner surface of Fallopian tubes |
Three identical heat conducting rods are connected in series as shown in the figure. The rods on the sides have thermal conductivity 2K while that in the middle has thermal conductivity K. The left end of the combination is maintained at temperature 3T and the right end at T. The rods are thermally insulated from outside. In steady state, temperature at the left junction is \(T_1\) and that at the right junction is \(T_2\). The ratio \(T_1 / T_2\) is 
