1906.] PLACENTA IN UNGULATES. 83 



allantoic epithelium are alike involved in the process of degenera- 

 tion, the disintegrating cells being added to the mass of uterine 

 milk in which the twisted crumpled filament is embedded, all, 

 indeed, that remains is the fibrous connective-tissue lamella which 

 separated the two epithelial layers. 



The sti'ucture, however, to which I wish here to draw attention 

 is a thickened fibrous ring which lies at the base of the terminal 

 filament and surrounds the narrow aperture by which the central 

 communicates with the terminal portion of the allantoic cavity. 

 The ring arises by a dense local hypertrophy of the connective 

 tissue (splanchnopleuric and somatopleuric) separating the epithelia 

 of the allantois and trophoblast : on the central side of the ring- 

 blood-vessels [b.v.) are found in this connective tissue, and the 

 two epithelia (tr. and all.) persist; on the terminal side the 

 epithelia degenerate and the blood-vessels are absent, the supporting- 

 lamella of connective tissue alone remains. This lamella springs 

 from the thickened " chorionic ring," as I will call it, and at its 

 base are two rings of muscular tissue forming a sphincter {sph.), 

 which apparently serves to prevent the escape of allantoic fluid 

 after the disintegration of the terminal portion. 



The figure, in which one half of the chorionic ring only is shown, 

 is taken from a section of the membranes of an embryo sheep 

 measuring 27 cm. (last month of pregnancy). 



4. The Distribution of Glycogen in the Placenta. 



The presence of this body in the Ruminant foetal membranes 

 did not escape the notice of its discovei-er, Claude Bernard. 



Bernard showed that the rounded or irregular, flattened or 

 papilliform bodies with which the internal surface of the amnion 

 is covered contained large quantities of glycogen, the quantity 

 increasing up to about the flfth month of gestation and then slowly 

 diminishing towards the end ; with the diminution of the glycogen 

 he described a fatty degeneration of the amniotic bodies and the 

 deposition of ciystals of calcium oxalate. He further demonstrated 

 the presence of glycogen during the earlier stages of pregnancy 

 in many embryonic tissues — the skin, lungs, intestinal villi, uterus, 

 bladder, ureters, renal tubules, and muscles ; not, however, in the 

 liver until late in foetal life, when it had disappeared from the 

 other organs. Bernard regarded the amniotic bodies as a store- 

 house of reserve carbohydrate, and pointed out that the percentage 

 of sugar (dextrose) found in the amniotic fluid steadUy increased 

 as the glycogen in the amnion diminished. 



Creighton has stated that glycogen may be found also in the foetal 

 cartilages, especially during iDone-formation, and in the choroid 

 plexuses of the brain. 



To these facts I am able to add but little. I have, however, 

 succeeded in finding glycogen in the uterine epithelium, both 

 superficial and glandular (in the Cow), and in the subepithelial 

 connective tissue in the Sheep, and further in the uterine milk. 



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