Reproductive anatomy

Reproductive anatomy

In the early days of AI there was controversy among researchers about the optimum site for semen deposition. A study conducted in Canada provided evidence that fertility was highest when semen was deposited in the uterine body. Researchers currently are reexamining insemination technique to determine the proper site of semen deposition.

Failure to understand the anatomical and functional relationships among the various tissues and organs of the reproductive system may lead to consistent insemination errors. Most AI training schools use excised tracts to illustrate reproductive anatomy. Often the tracts are dissected to allow students to view the interior of the uterus. This is a useful exercise; however, dissection can distort the relationship between various regions. Figure 1 is an illustration of the reproductive anatomy of the cow and a radiograph (photograph of an X-ray) of the cervical region and uterus. Radiography allows students to view the intact tract and simultaneously observe the interior of the uterine body and horns and, in many cases, the cervical canal.

General tips for insemination technique

§ To avoid the possibility of entering the urethral opening on the floor of the vagina, the insemination rod should be inserted into the vulva upward at a 30 ̊ to 40 ̊ angle.

§ The anterior portion of the vagina, termed the fornix vagina, tends to stretch rather easily when the insemination rod is pushed forward and beyond the cervix. This may give the false impression that the rod is advancing through the cervix, when indeed it is above, below, or to either side of the cervix. The inseminator should be able to feel the rod within the vaginal fold, but unable to feel the rod tip within the cervix.

§ Remember to place the cervix onto the insemination rod. Maintain slight forward pressure on the rod while manipulating the cervix slightly ahead of the rod.

§ The target for semen deposition, the uterine body, is quite small (Figure 1). Accurate rod tip placement is probably the most important skill involved in the whole AI technique. Inseminators generally identify this target area by feeling for the end of the cervix and the tip of the rod as the rod emerges through the internal os or opening. Depositing the semen in the cervix or randomly in the uterine horns may result in lower conception rates.

§ Once the rod tip is aligned with the internal cervical os, deposit the semen. Semen deposition should take about five seconds. Slow delivery maximizes the amount of semen delivered from the straw and minimizes the unequal flow of semen into one uterine horn.

§ During the process of semen deposition, take care that the fingers of the palpating hand are not inadvertently blocking a uterine horn or misdirecting the flow of semen in some manner.

§ Be careful not to pull the insemination rod back through the cervix while the semen is being expelled.

§ If the cow has moved during semen deposition or you think the rod has moved, stop the semen deposition and correctly reposition the rod tip before continuing semen deposition.

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