الفهرس 
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Abstract
TGF-β regulate a wide variety of biological processes including cell growth, apoptosis, differentiation, migration, extracellular matrix production, angiogenesis, immunity, and development. So, the present study aimed to investigate the response of ameloblast, odontoblast and osteoblast to TGF-β in tooth germ histologically and ultrastructurally.
Four young adult male and 12 adult female albino rats were used in this study. The female rats were mated over night with male rats. The female rats were divided into two main groups:
1) The group I (control group), that consisted of 6 rats that received intramuscular injection with 0.1 m1 PBS every two days from the first day till giving birth. Their off-springs were considered the control group.
2) The group II (experimental group): consisted of 6 rats that received intramuscular injection with TGF-β 40 ng dissolved in PBS every two days from the first day of pregnancy till giving birth. Their off-springs were considered the control group.
Summary
4 days after birth, there are 40 off-springs of rat were killed. The sections were stained by hematoxyline and eosin and Immunohistochemistry for histological study, and other sections stained with uranyl acetate and lead citrate to be examined by TEM. Data was statistically analyzed.
Light microscopic examination revealed that ameloblasts of group II showed marked variation in the height of the cuboidal cells, with central placed nucleus which were detached in some area from the underlying enamel matrix. While other areas appeared with attached ameloblasts with loss of saw appearance of Tome’s process in almost all of ameloblasts.
Moreover, Odontoblastic layer with irregular arrangement and loss of pseudostratified arrangement appeared in some regions. There were some empty spaces infiltrating the odontoblastic layer. The odontoblastic layer was attached to predentin in some areas and detached in others. Dentin layer with dark stain in the area adjacent to predentin, while dentin was pale in the layer adjacent to the enamel matrix and it was variable in thickness. The predentin layer was ill defined in comparison to that of the control group and showed variable thickness. Osteoblasts were observed to be more in number than in the control
Summary
group and showed plumbed appearance with basophilic cytoplasm.
Statistically significant results showed in our study in ameloblast and odontoblasts height and enamel matrix, predentin and dentin thickness. Ameloblasts and odontoblasts height and predentin thickness showed higher value in group I compared to group II at all sites. While in enamel matrix and dentin thickness showed higher value in group II compared to group I at all site
Immunochemical examination by light microscope of anti-MMP-9 stained sections of the tooth germ of group II revealed that some of ameloblasts and odontoblasts. Both cells showed negative nuclear reaction and mild positive cytoplasmic reaction. On the other hand, few osteoblasts showed strong reaction while others gave negative reaction.
TEM examination for ameloblasts in TGF-β group showed intracellular hyaline areas. The cell membranes showed some broken areas with some cytoplasmic material appeared to be escaped into the intercellular spaces. Nucleus showed a relative disorganization and small size compared to control group. Irregular arrangements of peripheral chromatin with clumping in some areas were
Summary
observed. The rER and mitochondria were few with ill- defined cristae.
Odontoblasts showed apparent intercellular vacuolation between cells with densely packed rER at distal end and well defined mitochondria. Nucleus appeared open faced with peripheral localized chromatin condensation.
Osteoblasts with nucleus fill most of cell body with prominent nucleus with cytoplasmic vacuoles and numerous cytoplasmic processes. Few mitochondria were swollen with loss of cristae few dilated rER while other showed normal appearance. All results were.