2. They are well-formed and hollow but non-vascular.
3. They are mal-formed, and this has prevented their vascularization. The atrophy is different in the vascular and in the non-vascular villi.
Ch. Robin has best described this atrophy: 1. If the villus is non-vas cular, it is obliterated and undergoes fatty degeneration; 2. If the villus is vascular, the vessels are obliterated and the villus transformed into fibrous tissue, composed of longitudinal parallel bundles not continuous _ _ with the tissue of the wall of the villas. There is, also, a little amorph ous connective tissue and fine granulations, besides narrow and long nuclei, longitudinally directed and only made visible by acetic acid.
This obliteration occurs in the villi of different cotyledons indifferently.
In many villi, after obliteration, we find that the parietes contain fatty granulations, and real drops of oil, mostly spherical or oval. They are bright yellow at the centre and dark at the periphery. They are insol uble in acetic acid but soluble in liquor potasae. They are either irregu larly dispersed or collected into groups.
The villi of the decidua serotina are developed, ad infinitum, and form the placenta. But as Cauwenberghe justly renaarks, the disorders of the circulation, manifested during the development of the villi, differ greatly from those obtaining after the perfect formation of the placenta. Au thors, although agreeing about the former, disagree about the latter period.
Eigenbrodt and Hegar have noted apoplectiform destruction of the uterine mucous membrane, both in pseudo-membranous dysmenorrhces and on abortive ova of the early months. During this time the mucosa is thickened, its vessels grow large and numerous, their walls are thinned, they coalesce and form vascular labyrinths gorged with blood as the re sult of physiological congestion. The gradual penetration of the vessels' walls, thinned by the villi, also favor rupture of the vessels and extravasation (Cauwenberghe). Hemorrhage is very frequent during placental devel opment, and may be primary or secondary to morbid maternal or fcetal states. The blood comes, then, from the mother's circulation, and is sit uated in the decidua serotina.
When the placenta is once formed, one may observe either simple con gestion, the villi presenting no changes, or hemorrhages, apoplectiform extravasations, always due to changes in the villi. But these hemorrhages
undergo changes greatly altering the appearance of the lesion, hence di verse descriptions and different opinions, held by authors, not only as to the existence of such or such lesions but as to the connections between them. Some consider the lesions of the villi as merely secondary to the extravasations. Others consider the disease of the villi the chief element, and attach secondary importance to the hemorrhage& Some see the source of the hemorrhages in the maternal circulation and others in the fcetal.
II. Extravasations.
Jacquemier's work on this subject is the most complete. He claims that, unless arterial lesions exist, the hemorrhages are always due to tear ing of the veins, either in the placental tissue or in the decidua, outside of the placenta.
The seat of the extravasations depends on the development of the pla centa and the time of the hemorrhage, and the hemorrhages are either true extravasations or what are called by Jacquemier and others placental apoplexies.
When the placenta is fully formed, the blood, extravasated in the pla centa, cannot extend between the decidua and the chorion, but accumu lates on the external surface of the chorion and is limited to the lobe in which it was first extravaaated. Later, the placenta forms a compact mass, and the blood, not being able to reach so far, forms superficial foci -rarely reaching the external surface of the chorion. Occasionally, lesions of the umbilical vessels are merely consecutive to those of the utero-pla cental vessels.
The extravasations may present themselves in three distinct forms: 1. The blood is contained in a very irregular cavity. The neighboring tissues are infiltrated and colored red. The hemorrhagic foci often com municate with the external placental surface, which is torn. They are irregular, being sometimes on the placental border, and sometimes in its centre. In the latter case, they generally extend to the external surface of the chorion and to the cord. If they are at the points where the chief branches of the funis traverse the chorion, the blood sometimes infiltrates the tissues around the umbilical vein and artery. The hemorrhagic foci may be single or multiple and of the same or different dates.