The yolk sac and zonary placenatation in late gestation
Keywords: yolk, sac, feline. exocelom, 55 days
Interestingly, the yolk sac persists for most of pregnancy in carnivora; it is shown here in a feline fetus 55 days old. In other domestic species, it is no longer visible by the end of the first third of pregnancy.
Image size: 1404 x 772px
| Note: We have adopted the term chorioallantois (allantochorion) with ease, understanding that it is a combination of two membranes i.e. the chorion and allantois. Yet, in advanced gestation, we persist in referring to an"amnion" when in reality it is the amnioallantois; a combination of the amnion and allantois. The author is of course playing the devil's advocate here, knowing full well that these statements will never achieve traction in wider biology.... |
To understand this image and the presence of an overt exocelom in the carnivora, one should consult the diagram in another entry in LORI. The exocelom is present in all embryos and early fetus in all species but is rapidly ablated in those animals except for dogs and cats. It is easily appreciated during cesarian sections in companion animals, occasionally mystifying the surgeon
The urachus is present but not visible in this image. It runs of course in the umbilical cord existing into the allantoic cavity which is no longer present; stripped away here to show the amnion.
The specimen from which this small section arises in shown below. An in-depth discussion of the image is superfluous here because a similar LORI entry is to be found elsewhere. The image does however provide an alternative view of the same anatomy.
Image size: 2007 x 1239px
