Chondrocytes regulate anabolic and catabolic processes to maintain the extracellular matrix components. Catabolic activities depend on the proteolytic action of the matrix -degrading enzymes including ADAMTS (A disintegrin and metalloproteinases) and MMP (Matrix Metalloproteinase). The current study explored the distribution of MMP-9 in normal articular cartilages of the embryos rabbit. Articular cartilage has grown by appositional growth that the perichondrial stem cells differentiate into chondrocytes. MMP-9 positive perichondrial stem cells or chondroblasts and early chondrocytes. Mature chondrocytes exhibited weak immunoaffinity for MMP-9. In conclusion, MMP-9 was essential during chondrocytes growth. The current study alludes to the potential role of MMP-9 during the growth of the articular cartilage.

The integumentary system of birds is quite different from that of mammals. The
current study was applied on the skin covering the head of sudanese duck (cairina
moschata) from hatching day until the skin became mature. In all different ages. The
skin is composed of epidermis, dermis and subcutes. The epidermis consists of stratum
cornium and stratum germinitivum. The later is formed of stratum basal, stratum
intermedium and stratum transivitium. The dermis is divided into stratum superficiale,
stratum compactum, stratum laxum and lamina elastic. The skin of Sudanese duck was
as any bird, characterized by feathers which generate from dermal papilla. The dermal
papilla with the epidermal collar formed the blastema which found at early age,
particularly at hatching day. Feather follicle was completely mature at two months.
The completely formed feather was pushed by the new formed feather through the
same dermal papilla. The maturity of the skin of head region is mainly associated with
the maturity of the head feathers
 

The adverse impact of schistosomiasis on tissues is considered in generating a schistosomal
 vaccine. The purpose of this study was to evaluate the effectiveness of Schistosoma mansoni
 crude antigens as a therapeutic and prophylactic formulation in the inhibition of heat shock
 protein (HSP70), apoptosis, and CD3/CD20 expression in a liver and spleen mouse models
 using the immunohistochemistry (IHC) method. A total of sixty five mice were divided into
 five groups: 1) infected untreated group (G1), 2) therapeutic treated group (G2) with egg
soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP), 3)
 prophylactically treated group (G3) with cercarial antigen preparation (CAP), 4) combined
 treated group with three antigens (G4), and 5) control group (G5). The results we obtained
 showed that CAP, SEA, and SWAP antigens mitigated the deterioration and inflammation
 induced by infection. Apoptosis and sinusoidal injuries were significantly reduced when treated with CAP antigen before infection. After infection, using SEA and SWAP antigens
 may help lighten the liver's load. A high degree of activation in T and B cells in the liver and
 spleen is linked to this. Our findings shed light on the immunological mechanisms that
 contribute to the recovery from therapy and vaccination against schistosome damage.