OCR Text |
Show 1877.] BURSA FABRICII IN BIRDS. 313 In the Gallinee the bursa has a tubular or pyriform shape, with numerous well-marked alternating ridges and furrows, the latter highly glandular, on its internal surface. These ridges are most marked towards the superior (blind) end, and are formed by the projection into the interior of collections of lymphatic follicles. These last do not open by distinct pores into the cavity of the bursa, but are entirely closed, as shown by Signor Alesi and Ley dig. In the process of atrophy the peduncle becomes solid ; also the cavity of the bursa becomes shut off from the cloaca, and persists in this state for some time. Finally, however, the bursa seems to become reduced to a ligament-like structure, or to become fused with the general aponeurosis. In the Turkey the bursa is a long tubular sac, 2 inches long, with very well marked ridges and sulci. In all a pore marks the opening of the atrophied bursa. In Serpentarius the bursa is Fig. 4. a a Cut surface of posterior wall of bursa, b. Opening of cloacal chamber into bursa, c. Pointer passing from cavity of bursa to exterior, d. Pointer passed from cloaca into bursa through opening b; the upper part is supposed to be seen through the wall of cloaca, e. Clitoris. a large globular sac, with the glandular area confined to the apical region and a small aperture into the cloaca. In these respects it resembles Otis and Grus. In Porphyrio and Ocydromus it assumes the form of a long, narrow, cylindrical tube, the central cavity of which becomes closed up as atrophy advances. In CEdicnemus there is a similar form of bursa. In Attagis, on the other hand, the form is pyriform, more like that of the Passeres and Gallinee. |