Bundles of commissural fibres pass from the ganglion cells of one side of the cord to the peripheral nerves of the other.
It is mainly characterized by the presence on the ventral border of definite transverse commissural fibres.
The supra-oesophageal ganglia are still entirely formed of undifferentiated cells, and are without commissural tissue like that present in the ventral ganglia.
In other particulars, as in the amount of nerve cells in the ventral cords and the completeness of the commissural connections between the two cords, &c.
On its ventral side it exhibits fairly well-marked transverse commissural fibres, connecting the two halves of the ganglion.
The central region contains in its interior the commissural portion, forming a punctiform, rounded mass in each ganglion.
These constrictions are in the position of commissural bands of nervous matter; of these the limiting nervous strands between the thalamencephalon and mesencephalon and between the mesencephalon and the hind-brain are of primary importance.
The first of these commissural bands is in the position of the posterior commissure connecting the two optic thalami.
The commissuraltissue soon becomes continuous through the length of the ventral cord, and is also prolonged into the supra-oesophageal ganglia.
The corresponding ganglia of the two sides become subsequently united and the various ganglia become connected by their proper commissural cords.
The commissural tissue not only gives rise to the longitudinal cords connecting the successive ganglia, but also to the transverse commissures which unite the two halves of the individual ganglia.
A gradual separation of the ganglia next takes place, and the cells become confined to the ganglia, which are finally only connected by a double band of commissural tissue.
After the formation of the commissuraltissue the remaining cells of the cord form the true ganglion cells.
The inner portion of this curved rudiment becomes converted into commissural nerve-fibres, while the cells of the outer and upper portion assume the characters of ganglion-cells.
In Amphibians the two hemispheres become united together immediately in front of the lamina terminalis by commissural fibres, forming the anterior commissure.
Along the sides of the infundibulum run the commissural fibres connecting the floor of the mid-brain with the cerebrum.
The development of the commissural and ganglionic portions takes place much as in the Chaetopoda.
This commissure is probably homologous with, and derived from, a commissural band in the roof of the thalamencephalon, placed immediately in front of the pineal gland which is well developed in Elasmobranchii (fig.
The commissural fibres are continued downwards to meet the ventral chord, but their junction with the latter structure is not effected till late in embryonic life.
Hence the corpus callosum is a connecting or commissural structure, which brings the gyri of the two hemispheres into anatomical and physiological relation with each other.
Behind the body the two halves diverge much more from each other, and form the posterior pillars, in the triangular interval between which is a thin lamina of commissural fibres called the lyra (fig.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "commissural" in a variety of sentences. We hope that you will now be able to make sentences using this word.
