The vas deferens

The vas deferens, or ductus deferens, runs from the cauda epididymis to join with the urethra in the pelvic region of the stallion. It is 25-30 cm in length and 4-5 mm in diameter, except, as already discussed, where it widens out to form the ampullae near the urethral junction (Gebauer et al., 1974b). The wall of the vas deferens is thick, in comparison with the diameter of the lumen, and there are three layers of smooth muscle fibres: the inner oblique, the middle circular and the outer longitudinal (Fig. 3.10). The thick muscular

Vas Ductus Deferens

middle circular muscle

•inner oblique muscle

-folded lumen

■spermatozoa epithelium

Fig. 3.10. Transverse cross-sectional view through the vas deferens, illustrating the relatively large muscular walls.

outer longitudinal muscle middle circular muscle

•inner oblique muscle

-folded lumen

■spermatozoa epithelium

Fig. 3.10. Transverse cross-sectional view through the vas deferens, illustrating the relatively large muscular walls.

wall is responsible for the peristaltic contractions that actively propel spermatozoa and its associated fluids from the testis to join the urethra. The lumen of the vas deferens is lined by folds, and this is especially evident where it nears the caudal epididymis. These folds increase the surface area for storage of spermatozoa.

The vas deferens enters the abdominal cavity of the stallion from the testis, via the inguinal canal. It passes through this canal, in the body wall, along with the testicular blood and nerve supply and in close association with the cremaster muscle (Fig. 3.11). The cremaster muscle, as it passes into the body cavity, is divided into two: the internal cremaster muscle running the length of the canal and lying between the blood and nerve supply and the vas deferens; and the external cremaster muscle, the larger portion, which lies lateral to the canal. Both these cremaster muscle blocks are responsible for supporting the testis and for the retraction of the testis up towards the abdomen in response to cold, fear and shock.

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  • Layla Ross
    Why vas deferens folded lumen?
    8 years ago

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