In accordance with this manner of feeding, the mouth is kept permanently open and prevented from collapsing by a pair of skeletal cornua belonging to a sustentacular apparatus (the nuchal skeleton), the body of which lies within the narrow neck of the proboscis; the latter is inserted into the collar and surrounded by the anterior free flap of this segment of the body.
The nuchal skeleton is a non-cellular laminated thickening of basement-membrane underlying that portion of the stomochord which lies between the above-mentioned pouches and the orifice into the throat.
sk, body of nuchal skeleton.
Here the sexes also differ in coloration, the males having the head and breast black, and the females the same parts chestnut; but all have a yellow nuchal crescent (whence the name of the group).
Intrauterine lethality of trisomy 21 fetuses with increased nuchal translucency thickness.
It is not a simple diverticulum of the collar-gut, but a complex structure possessing paired lateral pouches and a ventral convexity (ventral caecum) which rests in a concavity at the f_ ont end of the body of the nuchal skeleton (fig.
At the point where the stomochord opens into the buccal cavity the nuchal skeleton bifurcates, and the two cornua thus produced pass obliquely backwards and downwards embedded in the wall of the throat, often giving rise to projecting ridges that bound a dorsal groove of the collar-gut which is in continuity with the wall of the stomochord (fig.
The Leydigian or nuchal organ is supposed to be auditory and to contain an otolith.
Between 10 and 14 weeks of pregnancy, physicians may use an ultrasound to look for a thickness at the nuchal translucency, a pocket of fluid in back of the embryo's neck, which may indicate a cardiac defect in 55 percent of cases.
Nuchal translucency-A pocket of fluid at the back of an embryo's neck, visible via ultrasound.
Called nuchal translucency, the measurement tends to be larger in fetuses with genetic abnormalities such as Down syndrome, trisomy 13, trisomy 18, Turner syndrome, and triploidy.
A specialized ultrasound exam measures the thickness of the back of the fetus's neck (called nuchal lucency).
Sound waves will be recorded to measure the fluid beneath the skin at the back of the baby's neck, this is called nuchal translucency.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.