The ovarian bursa and infundibulum
Key words: canine, ovary, pyometra, infundibulum, corpora lutea
This image shows an opened ovarian bursa taken from the reproductive tract of a seven year old bitch during the luteal phase, two weeks after ovulation.
Image size: 3500x1985px
The normal, small opening to the peritoneal cavity was cut extended to show the ovary and bursa. This ovary contained 10 corpora lutea. The contralateral ovary contained several more corpora lutea and collectively they supporting pyometra in this bitch. Her reproductive tract is shown elsewhere.
The infundibulum is usually difficult to delineate, being similar in color to the internal surface of the bursa and rather amorphous in appearance. However, when these structures are submerged in water, the infundibulim, its ostium and folded structure become obvious. The uterine tube runs within the wall of the bursa and due to the presence of large deposits of adipose tissue in this area, it is almost impossible to demonstrate without careful dissection.
Note: Humans and anthropoid apes do not have ovarian bursae but the majority of animals do. In most domestic animals, ovarian bursae are sac-like and lie adjacent to their ovaries. In other animals, canids and rodents included, the ovarian bursae cover the ovaries far more completely. In an animal with an ovarian bursa, the uterine tube (fallopian tube) runs within the wall of the bursa, connecting the infundibulim to the uterine lumen.
The infundibulum is usually difficult to delineate, being similar in color to the internal surface of the bursa and rather amorphous in appearance. However, when these structures are submerged in water, the infundibulim, its ostium and folded structure become obvious. The uterine tube runs within the wall of the bursa and due to the presence of large deposits of adipose tissue in this area, it is almost impossible to demonstrate without careful dissection.
Note: Humans and anthropoid apes do not have ovarian bursae but the majority of animals do. In most domestic animals, ovarian bursae are sac-like and lie adjacent to their ovaries. In other animals, canids and rodents included, the ovarian bursae cover the ovaries far more completely. In an animal with an ovarian bursa, the uterine tube (fallopian tube) runs within the wall of the bursa, connecting the infundibulim to the uterine lumen.
In bitches, the bursa surrounds the ovary almost completely and only a small slit-like opening allows communication between the peritoneal cavity and the inside of the bursa. It is therefore, possible to ovariectomize thousands of bitches, yet never to see an ovary! Indeed, only a small section of the ovary can be seen through the opening of the ovarian bursa.
Interestingly, the purpose of ovarian bursae is not clear. They are not essential for capture of oocytes because the ovarian bursae have been surgically removed in mice but conception was still possible. Bear in mind too, that humans do not have ovarian bursae yet the world struggles with overpopulation! It is however, clear that the unfundibulum plays an essential role in the capture of oocytes at the time of ovulation. Through increased turgidity and changes in cilliary action during estrus, the folds and villi of the infundibulum trap oocytes and guide them into the ampullae of the uterine tube. This is a source of amazement because the infundibulum does not cover the ovary in any animal known to the author and in many cases lies some distance from a site of ovulation.
The macroscopic appearance of the infundibulae of various species are variable, some being folded and lace-like as in cattle and others, having thicker folds as seen here, in bitches.
Interestingly, the purpose of ovarian bursae is not clear. They are not essential for capture of oocytes because the ovarian bursae have been surgically removed in mice but conception was still possible. Bear in mind too, that humans do not have ovarian bursae yet the world struggles with overpopulation! It is however, clear that the unfundibulum plays an essential role in the capture of oocytes at the time of ovulation. Through increased turgidity and changes in cilliary action during estrus, the folds and villi of the infundibulum trap oocytes and guide them into the ampullae of the uterine tube. This is a source of amazement because the infundibulum does not cover the ovary in any animal known to the author and in many cases lies some distance from a site of ovulation.
The macroscopic appearance of the infundibulae of various species are variable, some being folded and lace-like as in cattle and others, having thicker folds as seen here, in bitches.
References.
G.L.Kelly. 1939 Effect of opening the ovarian bursa on fecundity in the albino rat. The Anatomical Record. 73: 401–405
Knoll, B. and Talbot P. 1998. Cigarette smoke inhibits oocyte cumulus complex pick-up by the oviduct in vitro independent of ciliary beat frequency. Reproductive toxicology. 12: 57-68
Lyons, R.A. et al 2002. Fallopian tube ciliary beat frequency in relation to the stage of menstrual cycle and anatomical site. Human Reprod. 17:584-588
G.L.Kelly. 1939 Effect of opening the ovarian bursa on fecundity in the albino rat. The Anatomical Record. 73: 401–405
Knoll, B. and Talbot P. 1998. Cigarette smoke inhibits oocyte cumulus complex pick-up by the oviduct in vitro independent of ciliary beat frequency. Reproductive toxicology. 12: 57-68
Lyons, R.A. et al 2002. Fallopian tube ciliary beat frequency in relation to the stage of menstrual cycle and anatomical site. Human Reprod. 17:584-588
