A cytoarchitectonic study of the spinal cord of the domestic fowl Gallus gallus domesticus. I. Brachial region

Substance P, somatostatin, and methionine enkephalin immunoreactive elements in the spinal cord of the domestic fowl, Gallus domesticus

The occurrence and distribution of substance P (SP), somatostatin (SOM), and enkephalin (ENK) immunoreactive elements were examined in the spinal cord of the domestic fowl, Gallus domesticus. SP immunoreactive fibers and their varicosities were densest in laminae I and II, although they were also found within deeper regions of the dorsal horn. In contrast, the intermediate gray area, the area around the central canal, and the ventral horn, contained fewer SP immunoreactive fibers. The distribution of ENK immunoreactivity in the gray matter was similar to that described for SP although immunoreactive fibers were denser around the central canal and in the intermediate zone. Few SOM immunoreactive fibers were present in the dorsal horn, the area around the central canal, and the ventral horn. All three peptidergic immunoreactive elements were found in and around the nucleus of Terni, an autonomic area. Throughout the lumbosacral enlargement SP, SOM, and ENK immunoreactive varicosities were found adjacent to the lumbosacral sinus and in fibers traversing the glycogen body. In addition, at caudal lumbar and rostral sacral levels a plexus of SP and SOM immunoreactive fibers was observed to be in close relationship with presumed motoneurons.

A cytoarchitectonic analysis of the spinal cord of the pigeon (Columba livia)

The spinal gray of the pigeon is described cytoarchitectonically to establish a foundation for anatomical and physiological studies of the pigeon spinal cord. The material includes segments from the high cervical cord through the lumbosacral enlargement, and nine cellular layers are described. In addition to this laminar organization, various distinct cell groups such as the dorsal magnocellular column, column of Terni, marginal cells and lobes of Lachi are described. Layers I-IV occupy the head of the dorsal horn, are apparent at all spinal levels examined, and represent the clearest case of laminar organization of the spinal gray of the pigeon. Layer V occupies the full extent of the neck of the dorsal horn at all segmental levels investigated. Also, the dorsal magnocellular column is situated in the central region of this layer from the rostral pole of the cervical enlargement through the lumbosacral enlargement, and arguments are advanced that this cell column is homologous to the column of Clarke. In the intermediate zone a Layer IV is defined, but it is apparent only at the enlargements. Layers VII-IX constitute the ventral horn, Layer IX being the motoneuronal cell groups. With the exception of the motoneuronal groups, the boundaries of the ventral horn layers are considerably less distinct than those of the dorsal horn, and no attempt is made to distinguish Layers VII and VIII at lumbosacral levels. At the enlargements there is a prominent lateral motoneuronal cell group consisting of large cells. It is generally concluded that the cytoarchitectonic organization of the spinal gray of the pigeon bears a rather close resemblance to that described for various mammalian species, particularly with respect to the dorsal horn.