Defense of the Master's thesis by student Celine Jameel Sultan.

Student Celine Jameel Sultan from the Department of Human Anatomy completed the defense of her Master's thesis titled:

**"Regional Variations in Histomorphometric and Immunohistochemical Expression of CD105 of Mesenchymal Stem Cells in Normal Term Human Umbilical Cord."**

The aim of this study was to assess regional differences in the histomorphometric and immunohistochemical expression of CD105 in mesenchymal stem cells within the normal human umbilical cord.

The immunohistochemical expression of CD105 in mesenchymal stem cells (MSCs) showed significantly higher values in the maternal portion of the cord compared to the fetal and middle sections. The central part of the placenta was identified as having the highest CD105 value for MSCs. CD105 was described as the most specific marker for detecting MSCs in the umbilical cord. There were more MSCs in the maternal part of the cord than in the middle and fetal parts in early reproductive age (18-30) pregnant women. This was assessed using immunohistochemical expression of CD105 in Wharton's Jelly (WJ), a gelatinous substance consisting of various forms of collagen and proteoglycans, which protects the arteries and veins from pressure and torsion.

The diameter of the maternal portion of the umbilical cord showed a high value, with the middle and fetal parts also showing high values, indicating increased cellularity in the maternal part of the cord compared to the other parts, due to its proximity to the placental tissues. The diameter of the umbilical artery in the fetal part showed high values compared to the middle and maternal parts of the cord, attributed to large-diameter vessels originating from the fetal body through the internal iliac arteries crossing the umbilical cord. Measurement of intercellular spaces revealed significant statistical differences in the fetal part compared to the middle and maternal parts of the cord and the central part of the placenta, attributed to lower MSCs in the fetal portion of the umbilical cord.

The measurement of MSC thickness did not reveal significant values. However, the maternal part had similar values to the central placenta part due to the close association of cells in these two areas. Wharton's Jelly measurements showed a significant high value in the fetal part compared to the maternal and middle parts of the cord, where MSCs were dispersed within Wharton's Jelly. The diameter of the umbilical vein was high in both the fetal and maternal parts compared to the middle part of the cord.

The immunohistochemical expression of CD105 was considered the most specific marker for detecting MSCs in the maternal part of the cord compared to the other sections. This marker was specifically expressed by these MSCs in the umbilical cord.

The defense committee consisted of:

- Professor Dr. Thaer Mahmoud Farhan (Chair)

- Assistant Professor Dr. Haider Hamadi Abdul Amir (Member)

- Assistant Professor Dr. Diaa Abdul Hussein (Member)

- Professor Dr. Haider Abdul Rasul Jaafar (Supervisor)

The thesis was successfully accepted.