Adrenal cortex regeneration in ethane dimethanesulfonate administered rat model

Aim: To investigate the parallel morphological and biochemical regeneration of Leydig cells in the adrenal gland after ethane dimethanesulfonate (EDS) administration. Materials and methods: We divided 72 male rats into two groups: the control and EDS groups. Rats in the EDS group received a single dose of EDS (75 mg/kg) intraperitoneally and were sacrificed on days 7, 21, 35, and 63 respectively. Adrenal gland tissue samples obtained from the sacrificed rats were analyzed under light microscopic, immunohistochemical, biochemical, and quantitative methods. Results: In contrast to Caspase-3 expression, 3βHSD and Ki67 expression and thickness of the zona reticularis (ZR) layer and testosterone levels significantly decreased on the 7th, 21st, and 35th days after single-dose EDS. However, 3βHSD and Ki67 expression, testosterone levels, and the ratio of ZR thickness of the EDS group were seen similar to the control group on the 63rd day following EDS administration, but experienced decreasing Caspase-3 expression. After EDS administration, we observed a significant regeneration in the ZR layer of the adrenal gland on the 63rd day. Conclusion: EDS-injected animal models can be used to investigate the development of Leydig cells and assess the turnover of the adrenal cortex (adrenal insufficiency) per time

Molecular Mechanism of Somite Development

From third week of gestation, notochord and the neural folds begin to gather at the center of the embryo to form the paraxial mesoderm. Paraxial mesoderm separates into blocks of cells called somitomers at the lateral sides of the neural tube of the head region. At the beginning of the third week somitomeres take ring shapes and form blocks of somites from occipital region to caudal region. Although somites are transient structures, they are extremely important in organizing the segmental pattern of vertebrate embryos. Somites give rise to the cells that form the vertebrae and ribs, the dermis of the dorsal skin, the skeletal muscles of the back, and the skeletal muscles of the body wall and limbs. Somitogenesis are formed by a genetic mechanism that is regulated by cyclical expression of genes in the Notch, Wnt and fibroblast growth factor signaling pathways. The prevailing model of the mechanism governing somitogenesis is the “clock and wave front”. Somitogenesis has components of periodicity, separation, epithelialization and axial specification. According to this model, the clock causes cells to undergo repeated oscillations, with a particular phase of each oscillation defining the competency of cells in the presomitic mesoderm to form a somite. Any disruption in this mechanism can be cause of severe segmentation defects of the vertebrae and congenital anomalies. In this review, we discuss the molecular mechanisms underlying the somitogenesis which is an important part of morphogenesis. [Archives Medical Review Journal 2013; 22(3.000): 362-376