An Ultrastructural Study of Endoplasmic Reticulum of Mammary Secretory Cells in Rabbits During Lactation and Regression Stages

The objective of the research was to study the changes of the Endoplasmic Reticulum (ER) in mammary epithelial cells of rabbits during lactation and regression stages. Our results using conventional transmission electron microscopy has shown that ER is changed during the various mammary gland development stages. We found that the average relative volume of ER achieves 17.7±2.464% of cytoplasm volume in the stage of lactation. During regression ER relative volume decreased to 1.274% of the cytoplasm. This difference compared to lactation is statistically significant (p<0.01). Relative surface of ER during lactation reaches 5,630±1,033 µm²/µm³ of cytoplasm. We found a decrease of relative surface of ER to 0.192±0.069 µm²/µm³ of cytoplasm during regression stage. The average size of ER cisternae and tubules reach 0,0953±0,012 µm at lactation stage. During a stage of regression the average size of ER cisternae and tubules is 0.171±0.154 µm. This difference compared to lactation is not statistically significant.