Vascular Changes in the Corpus Luteum During Early Pregnancy in the Cow

Abstract

Abstract. The present study determined vascular changes in the bovine corpus luteum (CL) at Day 16 (early maternal recognition period) and Day 40 in early pregnancy and compared them to the CL from Day 12 and Day 16 of the estrous cycle. The CLs were analyzed in the central and peripheral regions, where site-depending features of vessels and angiogenic factors are evident. The same protein level of the endothelial cell marker von Willebrand factor was retained in the CL from Day 16 of the estrous cycle to Day 40 of early pregnancy. The protein level of pericytes and smooth muscle cells was determined using smooth muscle α-actin; the level decreased at Day 40 of early pregnancy in both regions of the CL. No significant change in the expressions of vascular endothelial growth factors VEGF164 and VEGF120 mRNA occurred from Day 16 of the estrous cycle until Day 40 of early pregnancy. Angiopoietin (ANGPT)-2 / ANGPT-1 mRNA ratio (an index of instability of vasculature) increased in the periphery at Day 16 of the estrous cycle and then decreased until Day 40 of early pregnancy. The results suggest that there is no difference in vascular structure between non-pregnant and pregnant luteal tissue during the early maternal recognition period (Day 16). Also, luteal rescue by early pregnancy may be not associated with further blood vessel formation but rather may be related to the decrease of blood vessels per unit of area and blood vessel stabilization in the bovine CL. he corpus luteum (CL) is temporarily formed in the ovary following ovulation and secretes progesterone (P) to regulate the estrous cycle and to support the establishment of pregnancy. In cows, the CL begins to regress within 17-18 days after ovulation during the estrous cycle but retains a functional lifespan of more than 200 days during pregnancy [1]. Up to 40% of total embryonic loss occurs between Days 7 and 17 of pregnancy [2,3], which is a period associated with inadequate P concentrations. Thus, some changes of function and morphology in the CL to approve conception are critical during the estrous cycle, the early maternal recognition period and early pregnancy in the cow.Several distinct cell types, such as small and large luteal cells, vascular endothelial cells and pericytes, are distributed in the bovine CL [4]. More than 50% of cells in the mature CL are of vascular origin [4]. Alterations in luteal vascularity are associated with the luteinization and formation of the CL [5]. Angiogenesis is critical to development of the CL, as an inadequate microvasculature compromises luteal function [6]. The formation of a dense capillary network in the ovary enables the hormone-producing cells to obtain the oxygen, nutrients and also precursors necessary to synthesize and release different hormones essential for maintenance of the ovarian functions. Large luteal blood vessels, i.e., arteriolovenous vessels, have a smooth muscle cell layer and exist in the peripheral, but not central, region of the rabbit CL [7]. Indeed, in the bovine CL, the arteriolovenous ...

Possible role of interferon tau on the bovine corpus luteum and neutrophils during the early pregnancy

“…To collect the CL samples, 11 normal cyclic non-lactating German Holstein cows were used, in a similar way to our previous in vivo study in Germany (Beindorff et al 2010).…”

“…Ovariectomy was performed on day 16 (nZ4) of the oestrous cycle (not inseminated) as well as on day 16 (nZ7) of pregnancy. Collection of the ovaries was conducted by laparotomy (Beindorff et al 2010). After administration of epidural anaesthesia (2% procaine hydrochloride, Procasel, Selectavet, Weyarn-Holzolling, Germany), the long incision line was infiltrated subcutaneously and intramuscularly with 2% procaine hydrochloride with epinephrine (Isocain, Selectavet).…”

Gene Expressions in the Persistent Corpus Luteum of Postpartum Dairy Cows: Distinct Profiles from the Corpora Lutea of the Estrous Cycle and Pregnancy

“…The data indicate that CL function is able to persist for a significant amount of time with the interference of PGF 2α . We have previously shown that luteal mRNA expressions of angiogenic factors such as VEGF 120 and VEGF 164 , fragments of VEGF-A, do not differ between the late luteal phase and early pregnancy, while histological examination showed that angiogenesis does not occur in the CL during early pregnancy [42]. This finding is in agreement with the present study, where VEGF-A did not differ among the persistent CL, cyclic CL and CL of pregnancy, indicating that angiogenesis does not occur in the persistent CL or CL of pregnancy.…”

Possible involvement of IFNT in lymphangiogenesis in the corpus luteum during the maternal recognition period in the cow

“…Seven normal cyclic German Holstein cows were used as in previous in vivo study in Germany (Beindorff et al 2010). Briefly, the animals were divided into four groups: ovariectomy was performed on days 12 and 16 (C12 and C16, nZ5) of the estrous cycle (not inseminated) as well as on days 16 and 40 (P16 and P40, nZ5-7) of pregnancy.…”

“…The development of the bovine CL is accompanied by active angiogenesis, and the structure of blood vessels is retained during pregnancy (O'Shea et al 1989, Lei et al 1991, Beindorff et al 2010. Leukocytes, including monocytes/macrophages, granulocytes, and T lymphocytes, are localized to the CL in several species (Standaert et al 1991, Brannstrom et al 1994, Reibiger & Spanel-Borowski 2000.…”