Enzymic Correlates of Development, Secretory Function and Regression of Follicles and Corpora Lutea in the Bovine Ovary. PART II: Formation, Development and Involution of Corpora Lutea

Abstract

Activities of various hydrolases and dehydrogenases were studied during the formation, development and involution of cyclic corpora lutea and in the corpora lutea of early pregnancy. At 24 hours postovulation the luteal cells, whether of granulosal or thecal origin, contained demonstrable levels of Δ5-3β-hydroxysteroid dehydrogenase and the NADP and NADPH2 diaphorases. During the period of proliferation and cellular growth, enzymic activities in the luteal cells were moderate at first, and then increased. In the mature corpus luteum, activities of the dehydrogenases occurred in all luteal cells but were most intense in the large polymorphic luteal cells. Activities of hydrolytic enzymes, low in the immediate postovulatory period, increased with the development of the vascular system. Enzymic characteristics of corpora lutea of gestation were similar to those of cyclic corpora, except for phosphorylase activity which was observed in luteal cells in gestational corpora, but confined to the vascular walls in cyclic corpora. No increase in activities of 17β- and 20β-hydroxysteroid dehydrogenases (above those seen in pre-ovulatory follicles) were observed after incubation of sections of either mature cyclic or gestational corpora. Involution of cyclic corpora lutea began with degenerative changes in the blood vessels: pyknosis of the endothelial cell nuclei and a sudden decline in activities of hydrolytic enzymes in the vascular walls. Subsequently, the luteal cells showed a sharp decrease in activities of the dehydrogenases as well as other signs of regressive change. The cytochemical findings are discussed in relation to biochemical observations on steroid synthesis by the bovine corpus luteum.

Cell-specific variations and hormonal regulation of immunoreactive cytochrome P-450scc in the rat ovary

“…However, in regressed corpora lutea from previous rat oestrous cycles, expression of P-450scc in the few luteal cells remaining in the invading connective tissue tended to increase. The regression of the corpus luteum is accompanied by a decrease of steroid dehydrogenase and by an increase of phosphatase and aminopeptidase activities (Deane et al, 1962;Lobel & Levy, 1968). Apparently, the morphologically identifiable luteal cells continue to express the P-450scc enzyme.…”

Influence of Supernatants from Rabbit Luteal Tissue Cultures on Blastogenesis of Peripheral Blood Lymphocytes.

“…Activated Mφ produce some kinds of cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF)-α [10]. Mφ also exist in the CL [1][2][3][4][5][6].…”

The role of cytokines and adhesion molecules in maternal recognition and establishment of pregnancy in pig

“…Administration of PGF 2α into porcine corpus luteum resulted in massive invasion of macrophages into luteal tissue (Hehnke et al, 1990). This recruitment of immune cells does not occur at the similar time at early pregnancy (Lobel and Levy, 1968;Bogavandos et al, 1990). The changed ratio of PGF 2α : PGE 2 during peri-implantation period of pregnancy can abort an inhibition of TNF-α on luteal steroidogenesis and protect the CL against luteolysis.…”