Page 318 - Veterinary Histology of Domestic Mammals and Birds, 5th Edition

300 Veterinary Histology of Domestic Mammals and Birds

Penis of birds In species with a non-protrusible phallus, erection also
VetBooks.ir In birds with a protrusible phallus, the penis arises as the occurs due to engorgement with lymph, although in these
basis phalli in the ventral wall of the cloaca, where it rests species the erect phallus protrudes only slightly, if at all,
in a trough-like plate of fibrocartilage, the corpus fibrocar-
from the cloaca.
tilagineum. It incorporates a lymphatic cistern (cisterna
lymphatica basis phalli) that is partly divided into left and Accessory structures of the phallus
right components. The cistern continues as a narrow The vascular body of the phallus consists of a capillary
chamber (cisterna lymphatica corporis phalli) that extends tuft (originating from the pudendal artery) that is intri-
around the cutaneous and glandular phallic sacs (saccus cately intermingled with lymphatic vessels. Fluid passes
cutaneous phalli and saccus glandularis phalli). These sacs from blood capillaries into the interstitium, from which it
form the hollow interior of the body (corpus) of the phallus. enters the lymph vessels. The lymph passes through two
The more proximal cutaneous sac leads into the glandular ducts into the lymphatic cisterns of the phallus. Filling of
sac. In the non-tumescent phallus, the body is completely these cisterns is responsible for erection, aided by contrac-
invaginated and the junction between the cutaneous and tion of the m. sphincter cloacae.
glandular phallic sacs, the flexura phalli, is curved. During detumescence, the phallus is returned to its
During intumescence, lymph derived from the vas- invaginated state by the action of the typically striated
cular body of the phallus (see below) fills the lymphatic m. retractor phalli in the ventral wall of the cloaca,
cisterns to bring about erection. This results in eversion of with assistance from the elastic ligament of the phallus.
the cutaneous phallic sac. The glandular sac is not everted In waterfowl, lymph is pumped from the phallus by two
(it comes to lie within the cutaneous sac). As a result, the lymph hearts (cor lymphatica), each located above the
exteriorised flexura phalli becomes the tip (apex) of the transverse process of the first free caudal vertebra.
erect phallus. A phallic sulcus (sulcus phalli) spirals around
the free part of the erect phallus.

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