Lymphatic Involvement in the Disappearance of Steroidogenic Cells from the Corpus Luteum during Luteolysis

Abstract

In mammals, the corpus luteum (CL) is an essential endocrine gland for the establishment and maintenance of pregnancy. If pregnancy is not established, the CL regresses and disappears rapidly from the ovary. A possible explanation for the rapid disappearance of the CL is that luteal cells are transported from the ovary via lymphatic vessels. Here, we report the presence of cells positive for 3β-hydroxysteroid dehydrogenase (3β-HSD), an enzyme involved in progesterone synthesis, in the lumen of lymphatic vessels at the regressing luteal stage and in the lymphatic fluid collected from the ovarian pedicle ipsilateral to the regressing CL. The 3β-HSD positive cells were alive and contained lipid droplets. The 3β-HSD positive cells in the lymphatic fluid were most abundant at days 22–24 after ovulation. These findings show that live steroidogenic cells are in the lymphatic vessels drained from the CL. The outflow of steroidogenic cells starts at the regressing luteal stage and continues after next ovulation. The overall findings suggest that the complete disappearance of the CL during luteolysis is involved in the outflow of luteal cells from the CL via ovarian lymphatic vessels.

Podoplanin as Key Player of Tumor Progression and Lymph Vessel Proliferation in Ovarian Cancer

“…Regarding our observation concerning the existence of lymphatic vessels in the albicans body, we conclude that they could determine the destruction of steroidogenic cells, although this has not yet been fully elucidated (33).…”

Inflammation and angiogenesis in the corpus luteum

“…During the estrous cycle, the CL is developed from the ovulatory follicle and undergoes remarkable growth, differentiation and remodeling . If an oocyte is not fertilized, the CL will regress, with apoptosis of luteal cells and a decline in P4 synthesis . Furthermore, there are three different phases due to the luteal lifespan, namely, the developing, mature and regressing CL .…”

“…10 If an oocyte is not fertilized, the CL will regress, with apoptosis of luteal cells and a decline in P4 synthesis. 11,12 Furthermore, there are three different phases due to the luteal lifespan, namely, the developing, mature and regressing CL. 13 Due to the number of ovulation events and the length of cycles, the CL of rodents and primates presents obvious difference including luteal phase length, luteotropins and mechanisms of luteal regression.…”

Expression of matrix metalloproteinases in bovine luteal cells induced by prostaglandin F2α, interferon γ and tumor necrosis factor α

“…During structural luteolysis, luteal cells are eliminated by apoptosis and phagocytosis by macrophages [ 2 , 3 , 4 ]. We recently found that during structural luteolysis luteal cells flow out of the CL via lymphatic vessels [ 5 ], although the mechanisms regulating the outflow are unclear.…”

“…The aim of the present study was to validate possibility of the above idea. Since outflow of luteal cells occurs during luteolysis [ 5 ], we hypothesized that luteolytic factors increase MMP expression in luteal cells. To test this hypothesis, we investigated the effects of three factors that are known to induce luteolysis PGF, interferon γ (IFNG) and tumor necrosis factor α (TNF) [ 4 ]) on the mRNA expressions of four MMPs involved in degrading collagen and the basal membrane in cultured luteal cells.…”