Capillary blood flow to ovarian follicles, stroma and corpora lutea of anaesthetized sheep

Abstract

The radioactive microsphere technique was used to determine the rate of blood flow through vessels of up to 15 mum diameter in the ovaries of 23 anaesthetized sheep in the 72 hr preceding ovulation. The validity of the microsphere technique was established in two preliminary studies. On Days 14, 15 and 16 of the cycle the rate of blood flow (ml.min-1 .100 g-1 tissue) was 1122, 708 and 116 to the CL; 157, 258 and 140 to the stroma; and 627, 742 and 1096 to the follicles, respectively. Blood flow to grossly atretic follicles did not differ significantly from that to non-atretic follicles of an equivalent size. Change in blood flow do not appear to initiate or control the activation, steriodogenic function or atresia of follicles.

Growth and cellular proliferation of pig corpora lutea throughout the oestrous cycle

“…Accompanying rapid growth of the corpus luteum, dynamic changes in luteal vascularity occur throughout the oestrous cycle (Clark, 1900; Andersen, 1926;Basse«, 1943;Bruce and Moor, 1976;Reynolds, 1986;Reynolds et ah, 1992; Zheng et ah, 1993). The mature corpus luteum is highly vascular and receives one of the greatest rates of blood flow, per unit of tissue mass, of any organ (Reynolds, 1986;Niswender and Nett, 1988;Reynolds et ah, 1992Reynolds et ah, , 1994Redmer and Reynolds, 1996;Reynolds andRedmer, 1998, 1999).…”

Relative Levels of Thecal Blood Flow in Atretic and Non‐atretic Ovarian Follicles of the Conscious Sheep

“…It is reasonable to expect that some reduction of capillary blood flow in follicles undergoing atresia should occur. One possible explanation of the failure of Bruce and Moor (1976) to demonstrate a reduction in thecal blood flow in atretic follicles was the use of anaesthetised animals combined with the low numbers of microspheres retained by individual follicles. A similar technique has been used successfully to describe changes in blood supply to periovulatory follicles in ewes (Murdoch, Nix and Dunn, 1983).…”

“…Subsequent ultrastructural studies showed degenerative changes in the thecal capillaries of sheep follicles which were judged to be in the early stages of atresia (O'Shea, . These findings suggested that disruption of thecal capillary blood flow is an early event in atresia and might be responsible for the onset of follicular atresia, Bruce and Moor (1976) obtained measures of capillary blood flow in ovarian follicles of anaesthetised ewes by administering intracardiac doses of one million radioactive microspheres in order to fractionate cardiac output. They concluded that ^lood flow to grossly atretic foUicles did not differ significantly from that to non-atretic follicles of a similar size'.…”

Structure-Function Relationships in the Wall of the Ovarian Follicle

“…The capillary bed is less dense in other parts of the theca, and the larger vessels supplying and draining the thecal capillaries are more peripherally situated in and around the theca externa. Follicular blood flow is high, reaching levels comparable to those of functional luteal tissue when calculated per unit weight of tissue in the sheep (Bruce and Moor 1976).…”