Perhaps nothing is more mythic, feared, or misunderstood amongst novice incubators than the dreaded 'blood ring,' but what is it, really? The internet has all sorts of ideas: overgrowth of bacteria, decaying blood vessels clumping together, the most obvious and common sign of embryonic death...but just how common is it and what is its true nature?
First off, it isn't that common nor is it the only or even the most common sign of embryonic death. In fact they are kind of rare, I'd guess they occur in less than 5% of early quitters. While it is a certain sign of death, their scarcity makes them a bad indicator in general for finding early quitters, just because your egg doesn't have one doesn't mean it is viable, but if it does it most certainly isn't.
Second, what is the nature of these rare beasties? I've always leaned towards the broken and decaying blood vessel theory, while there may be bacterial infiltration in some cases, these should lead swiftly to rottenness and decay, an oozy stinky mess not consistent with the organized nature of the blood ring. Today I found a Day 4 quail egg with a nice blood ring and decided to photograph my findings, let's see what this thing is really made of:
This is what your eyes see, a bad, shaky pic of a hand held blood ring.
This is what the camera sees, a nice clear shot of what your eyes can barely discern. The ring can be any size or located at any place inside the shell except the air cell.
This is what is inside the egg. You can see a three day embryo complete with eyes and limb buds, notice the significant hemorrhage behind the eye/base of the skull and over the heart, as well as the infamous red ring. I have not looked at this under a microscope but grossly to me it looks like petechial or ecchymotic hemorrhage in both the blood ring and the embryo (tiny broken capillaries lead to delicate patterns of hemorrhage and bruising). Which may be basically the same thing as the collection of broken blood vessels theory, I'm guessing only a diehard pathologist would care about the minor histological differences, but whatever it is, the structure is very delicate, almost lace-like, not just a flotsam and jetsam of broken vessels. Very interesting! But this delicate pattern may break down over time to become a thick, marked red line as well, maybe I just caught this one early. But why does it form in some eggs but not in others? Is there a connection between the cerebral hemorrhage and the blood ring or is it just normal post-mortem changes? Does it only happen in embryos that die from certain issues (DIC, vascular accident, coagulopathy...) or is it just random? I don't have any answers but fascinating to consider!
First off, it isn't that common nor is it the only or even the most common sign of embryonic death. In fact they are kind of rare, I'd guess they occur in less than 5% of early quitters. While it is a certain sign of death, their scarcity makes them a bad indicator in general for finding early quitters, just because your egg doesn't have one doesn't mean it is viable, but if it does it most certainly isn't.
Second, what is the nature of these rare beasties? I've always leaned towards the broken and decaying blood vessel theory, while there may be bacterial infiltration in some cases, these should lead swiftly to rottenness and decay, an oozy stinky mess not consistent with the organized nature of the blood ring. Today I found a Day 4 quail egg with a nice blood ring and decided to photograph my findings, let's see what this thing is really made of:
This is what your eyes see, a bad, shaky pic of a hand held blood ring.
This is what the camera sees, a nice clear shot of what your eyes can barely discern. The ring can be any size or located at any place inside the shell except the air cell.
This is what is inside the egg. You can see a three day embryo complete with eyes and limb buds, notice the significant hemorrhage behind the eye/base of the skull and over the heart, as well as the infamous red ring. I have not looked at this under a microscope but grossly to me it looks like petechial or ecchymotic hemorrhage in both the blood ring and the embryo (tiny broken capillaries lead to delicate patterns of hemorrhage and bruising). Which may be basically the same thing as the collection of broken blood vessels theory, I'm guessing only a diehard pathologist would care about the minor histological differences, but whatever it is, the structure is very delicate, almost lace-like, not just a flotsam and jetsam of broken vessels. Very interesting! But this delicate pattern may break down over time to become a thick, marked red line as well, maybe I just caught this one early. But why does it form in some eggs but not in others? Is there a connection between the cerebral hemorrhage and the blood ring or is it just normal post-mortem changes? Does it only happen in embryos that die from certain issues (DIC, vascular accident, coagulopathy...) or is it just random? I don't have any answers but fascinating to consider!
