Abstract:
The ostrich industry is a small, important section of the economy in the Republic of South
Africa. The demand for ostrich products is high in the world, but the ostrich industry faces
some production problems, one of which is the low fertility of commercially farmed
ostriches.
This study aimed to determine the vasculature of the reproductive system in the male
ostrich and determine the kind of blood-testis and blood-epididymis barriers, since there is
no published information regarding this aspect. Thus 85 pre-pubertal and adult sexually
active male ostrich were studied. Arterial supply, venous drainage, microvasculature of the
male reproductive system, and blood-testis and blood-epididymal barriers, were
determined in this specie, for the first time. Results show that the pattern of the arterial blood supply to the reproductive organs of the
male ostrich is similar to that of the domestic fowl and pigeon. However, few highlighted,
distinctive, features were noted, the communication between the cranial renal arteries and
middle renal arteries via collateral circulation.
The pattern of the venous drainage of the reproductive organs of the male ostrich, was
similar to that described in the domestic fowl. However, important differences were the
fusion between the caudal renal veins and the existence of a unique caudal median vein
that had the caudal mesenteric vein as tributary.
The epithelial structure in the proximal efferent ducts was consistent with fluid absorption.
The fluid absorbed in the efferent ducts is harvested also by capillary lymphatics situated in
the interstitium.
Both the cranial and caudal segments of Ductus deferens and the Receptaculum ductus
deferentis displayed one vascular networks beneath the tubular epithelium and other
capillaries, venules, arterioles and collecting veins were in the periphery. Arterioles and
collecting veins were also under the serosa. Subepithelial capillaries, in those segments,
lacked fenestrations.
The spongy structure, in the root of phallus, exhibited several blood vessels in the strands.
The capillaries and the venules displayed fenestrations. The erectile tissue in the phallic
sulcus had the same features like the spongy in phallus. The spongy is comparable to
corpus paracloacal vascular body present in other avian species and it should be called
lymphobulbus phalli, it is the main source of lymph for phallus erection in the male ostrich.
There are similarities in the microvasculature pattern between ostrich and domestic fowl,
but there are some differences in the ostrich:
(i) Absence of fenestrations in the capillaries of testis,
(ii) Very simple and random distribution of stromal blood capillaries, arterioles and
venules in the epididymis, Endothelial fenestrations, only in the blood capillaries close to proximal efferent ducts,
(iv) Isolated lymphatic capillaries in the epididymis, occasionally, presented endothelial
fenestrations fitted with a membranous diaphragm,
(v) Existence of three vascular networks surrounding the tubule of deferent duct and
receptaculum, that were determined on the base of the distribution, location and
size of the vessels.
The blood-testis barrier of the ostrich is positioned: in (i) the capillary endothelium in the
interstitium, between adjacent seminiferous tubule, (ii) the boundary tissue, and (iii)
between spermatogonia and spermatocytes, and spermatogonia and Sertoli cells, and
finally, (iv) between Sertoli cells. The occluding junctional complexes between the various
tissue or cellular elements are mainly tight junctions.
The blood-epididymal barrier in the ostrich is revealed by participation of the endothelium
of the capillaries and venules in the epididymal region, as lanthanum is trapped there, it
does not appear beyond that point.
The blood-testis and blood-epididymal barriers are similar to those described for the
domestic rooster.