At no time was the amount of apoptosis observed in the corpora lutea as dramatic and widespread as we observed in collapsing atretic follicles in the same sections, which is further evidence for a slow and controlled process of tissue deletion in the corpora lutea. antibiotics levaquin
This study is the first to examine a single, most recent, generation of corpora lutea before (proestrus) and immediately after (estrus) the putative signal for regression as well as examining all populations of regressing corpora lu-tea. We have found that inflammatory/immune and regressive events are initiated (MCP-1 changes; monocyte/macrophage infiltration; apoptosis) and reinitiated (MCP-1 changes; apoptosis) at this time. The observed increases in monocyte/macrophage numbers and in apoptotic nuclei are consistent with the findings from previous studies. The timing of onset of these events is consistent with a role for the proestrous prolactin surge in initiating regression.
However, other hormones, such as ovarian steroids and LH, are also elevated during this time period. It is possible that one or a combination of these factors participate in the initiation of inflammatory/immune events in corpora lutea observed on estrus. The recruitment of monocytes/macrophages to regressing corpora lutea entering regression between proestrus and estrus is consistent with the effects of prolactin treatment in the hypophysectomized rat; however, the differentiation state of the macrophages present is altered, raising the question of what this differentiation means in terms of macrophage function in the tissue. The role of macrophages and other inflammatory cells in luteal regression remains an intriguing problem for future investigation.