This field shows only about half the magnum because it's so large even
at the lowest power I couldn't get it all in one view.
Author: Dr. Thomas Caceci
This field shows only about half the magnum because it's so large even
at the lowest power I couldn't get it all in one view.
The lumen is extremely patent, and there are deep clefts or crypts. Obviously this organ is designed for distensibility. The uniform basophilic staining of the submucosa is due to the glands located there. This portion of the oviduct makes the albumen coat, so its protein-synthesis capability is extremely well developed.
On occasion, two eggs are released from the ovary in quick succession, and travel down the tube together. When this happens, both will pass through the magnum more or less simultaneously and be wrapped in a single covering of albumen. That's what's known as a "double-yolker." You can spot these eggs in a pile pretty easily: they're considerably elongated compared to the proportions of a single-yolk egg.
The size of egg produced depends on the size of the bird producing it. This
sounds obvious, but in some birds egg-laying begins before physical maturity.
I once had a neighbor who raised chickens commercially, from the egg stage to
the "pullet" stage, at which time he'd sell them to a commercial egg
producer. If his buyer was delayed in getting the hens, they would start to
lay "pullet eggs," which ranged in size from about that of a bing
cherry to perhaps half the size of a full-grown hen's egg. Such small eggs have
little commercial value; he was glad to give them to me, and I sold them to
a baker, who measured his eggs for wedding cakes by the gallon, not the dozen;
so the size of individual eggs mattered little to him.
At high magnification both the lining epithelium and the underlying albumen glands in the submucosa are visible. The epithelium is stratified cuboidal to columnar. The massive glands are strongly basophilic because of their role in protein secretion for export; each of these cells is packed with rough endoplasmic reticulum.
Oviduct, chicken; H&E stain, paraffin sections, 20x and 400x
