This secondary median fold is very inconspicuous and slightly developed in the Cockroach, so that the transverse commissures between the developing ganglia are mainly contributed by the cellular substance of the lateral nervous band.
These nerves do not form a continuous cord extending throughout the body, but take fresh origin in each segment from the right and left longitudinal commissures alternately.
The distance apart, T, T, of the two commissures of the lips gives, very nearly, the distance from the superior border of the orbital arch to the base of the ear or the auditory meatus.
Between the lateral surfaces of the frog and the bars are found two angular cavities--the lateral lacunae, or the commissures of the frog.
There are eleven commissures in front of the first pair of legs (Pl.
These commissures exhibit a fairly regular arrangement from the region included between the first and the last pair of true feet.
I believe that there are at this stage three or four transverse commissures at any rate, which remain as indications of the separate ganglia, from the coalescence of which the abdominal cords are formed.
Posteriorly the two nerve-cords nearly meet immediately in front of the generative aperture, and between this aperture and the last pair of feet there are about six commissures passing between them (Pl.
Similar nerves to those behind are given off from the region in front of the first pair of legs, while at the point where the two ventral cords pass into the oesophageal commissures two large nerves (fig.
Longitudinal vertical section through the supra-oesophageal ganglion and oesophagealcommissures of Peripatus capensis.
Such a median structure has been described by Hatschek for Lepidoptera, and he states that it gives rise to the transverse commissures between the ganglia.
In correlation with the nerves given off from them to the skin the commissures are smaller in the middle than at the two ends.
From the commencement of the oesophageal commissures (oes.
Footnote 464: These commissures were perhaps observed by Saenger, loc.
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.
At a later stage these ganglia fuse into two continuous cords, united however by commissures corresponding with the previous ganglia.
At this stage the differentiation of the lateral elements into ganglia and commissurestakes place, and, according to Hatschek (No.
This ventral nerve-chain consists of a pair of longitudinal commissures or cords and a series of pairs of ganglia, arranged segmentally.
The interpretation of this stage is that in the invertebrate ancestor the nerve-masses were situated laterally and ventrally to the epithelial tube, and were connected together by commissures on the ventral side of the tube (Fig.
These are connected with the infra-oesophageal ganglia by the oesophageal commissures which encircle the oesophagus.
These two brains are connected together by commissures extending the whole length of the body, in which I have been unable to find any sign of ganglion-cells.
Thus in a crayfish, in which the oesophageal commissures had been cut, fungus was found to grow on the ventral side, but not on the dorsal carapace.
These areas, by uniting from side to side, give rise to the transverse commissures, and also by a linear coalescence to the longitudinal commissures of the cord.
The most characteristic parts of the Mammalian cerebrum are the commissures connecting the two hemispheres.
It is by a series of differentiations within this septum that the above commissures originate.
The section shews the commissures (x) uniting the posterior roots.
The commissures stain very deeply with the mixture of osmic and chromic acid, and form one of the most conspicuous features in successful longitudinal sections of embryos so hardened.
The commissures are unfortunately not represented in the figure with great accuracy; their outlines are in nature perfectly regular, and not, as in the figure, notched at the junctions of the cells composing them.
The section shews the commissures which dorsally unite the posterior roots, and also the junction of the anterior and posterior roots.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "commissures" in a variety of sentences. We hope that you will now be able to make sentences using this word.
