Local adjustment of blood and lymph circulation in the hormonal regulation of reproduction in female pigs--facts, conclusions and suggestions for future research.
Arteries, veins, capillaries and lymphatic vessels situated in the mesovarium and mesosalpinx of domestic animal species (pig, cow, sheep) form the periovarian vascular complex. Particular components of the periovarian vascular complex interact functionally and morphologically creating a specific environment for numerous physiological processes. The complex plays an essential role in the system of the retrograde transfer of the ovarian hormones. This phenomenon is especially well documented in pigs. The efficiency of the retrograde transfer of estradiol and progesterone from blood and lymph leaving the gonad to blood of the ovarian artery (expressed as percentage of their concentration in the ovarian venous blood) as well as the rate of the retrograde transfer of these hormones to the ovary (measured in nanograms or picograms per minute) is presented and discussed in this paper. No simple relationship was found between hormone concentration in ovarian venous effluent and the efficiency or the rate of their retrograde transfer during the estrous cycle. It appears that two processes contribute to the highly efficient retrograde transfer of ovarian hormones into the ovary in the periovarian vascular complex: 1/ direct hormone permeation from the ovarian vein into the adjacent branches of the ovarian artery through the counter-current mechanism; 2/ indirect permeation of ovarian hormones consisting of two stages. The first stage includes the permeation of hormones from lymph leaving the ovary via the subovarian lymphatic vascular network as well as lymph and venous blood, leaving the mesosalpinx and going to capillaries and tiny venous vessels in the entire mesovarium. These tiny mesovarium vessels connect and then branch out again to form the veno-venous network on the surface of branches of the ovarian artery. The second stage includes the permeation of hormones from the veno-venous blood into the branches of the ovarian artery. The authors present a hypothesis that the retrograde transfer of ovarian hormones may participate in the feedback regulation of ovarian function. The relationship between the retrograde transfer of ovarian hormones in the area of periovarian vascular complex and local elevation of steroid hormone concentrations in blood supplying the oviduct and uterus is presented. The paper also includes suggestions for future research.
Stefańczyk-Krzymowska
Stanisława
S
Division of Reproductive Endocrinology and Pathophysiology Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland. skrzym@pan.olsztyn.pl
Krzymowski
Tadeusz
T
D000735:Androstenedione / Q000097:blood; D000818:Animals; D004958:Estradiol / Q000097:blood; D005260:Female; D006728:Hormones / Q000097:blood*; D008208:Lymphatic System / Q000502:physiology*; D010053:Ovary / Q000098:blood supply*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012098:Reproduction; D013552:Swine / Q000502:physiology*; D014599:Uterus / Q000098:blood supply
D006728:Hormones; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol