Summary
Ultrasonographic images of the accessory sex glands of 8 stallions were recorded immediately prior to sexual preparation, immediately after sexual preparation, and immediately after ejaculation. Relative size changes, determined by measurements of ultrasonograms of accessory sex glands, were contrasted. Length and width of the bulbourethral glands increased significantly (P < 0.05) after sexual preparation and decreased significantly (P < 0.05) after ejaculation. The increase in bulbourethral gland volume following sexual preparation was correlated significantly (P < 0.01) with the number of false mounts attempted by stallions during sexual preparation. Diameter of the pelvic portion of the urethra did not change significantly (P > 0.05) after sexual preparation or after ejaculation. Prostate gland lobular and isthmic thickness increased significantly (P < 0.05) after sexual preparation and decreased significantly (P < 0.05) after ejaculation. Total and lumenal diameter of the ampullae increased significantly (P < 0.05) after sexual preparation and decreased significantly (P < 0.05) after ejaculation. Diameter of the ampulla wall did not change significantly (P > 0.05) after sexual preparation or ejaculation. Reduction of the lumenal area of the ampullae after ejaculation was not correlated (P > 0.05) to concentration of spermatozoa or total spermatozoa per ejaculate. Total and lumenal diameters of the vesicular glands increased significantly (P < 0.05) after sexual preparation and decreased significantly (P < 0.05) after ejaculation. Diameter of the vesicular gland wall did not change significantly (P > 0.05) after sexual preparation or ejaculation. The decrease in the diameter of the vesicular gland lumen after ejaculation was correlated (P < 0.05) to the volume of gel in the ejaculate.
The accessory sex glands of 4 stallions were measured by 3 experienced ultrasound operators and 3 inexperienced ultrasound operators. There was no significant (P > 0.05) effect of operator or experience level on dimensions measured.
