Ungulate Anatomy Lab 17

CONTENTS:

Lab Objectives
Anatomical Terms
Instructor Commentary
Dissection Images

Lab Objectives:

• Study the parts of the testicle and be able to differentiate right versus left testicles.

• Trace the ductus deferens to the genital fold and the ampullae. Then identify the other accessory sex glands in all available species.

• Identify the urethralis, ischiocavernosus and bulbospongious muscles and note that urethralis muscle fibers partially cover the bulbourethral glands.

• On equine specimens note the layers of the prepuce and the preputial ring. Then identify the glans penis, urethral process, fossa glandis and the small opening of the urethral sinus. Observe the urethral sinus on a midline sectioned demonstration specimen.

• On ruminant and porcine specimens note the retractor penis muscle and its attachments. Identify the parts of the penile sigmoid flexure and the elongated urethral process of small ruminant males.

• On the mare ovary note the ovulation fossa and smooth surface. On bovine ovaries note the elevated corpra lutea and follicles. Observe the ovarian bursa of all available species and identify the uterine tube, mesovarium, mesosalpinx and antimesosalpinx.

• Identify the broad ligament, the uterine horns and the bovine intercornual ligament. On mare tracts find the round ligament of the uterus which has a characteristic "tag".

• Make a dorsal incision from the vulva to the uterine body to expose the lumen of the female genital tract. Note the urethral orifice in all species and find the suburethral diverticulum in cow and sow tracts. Compare and contrast the cervical canal of all available specimens.

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Anatomical Terms:

Male Genitalia & Associated Structures
        cremaster m.
        parietal vaginal tunic
        mesorchium
        mesoductus
        visceral vaginal tunic
        testicle
        epididymis
                head
                body
                tail
                testicular bursa
        (be able to differentiate right & left testicles)
        genital fold
                uterus masculinus
        ductus deferens
                ampulla
        vesicular glands
        body of the prostate
        urethralis m.
        preputial ring
        glans penis
        urethral process
        fossa glandis
                urethral sinus
        ischiocavernosus m.
        corpus cavernosum penis
        bulbospongiosus m.
        corpus spongiosum penis
        retractor penis m.
        tunica albuginea
        crus of the penis ("pizzle eye" in bovine)
        sigmoid flexure (bov, por)
                proximal loop
                distal loop
        dorsal a. of the penis
        dorsal n. of the penis
        prepuce
                preputial muscle
                        cranial preputial m.
        bulbourethral glands
        preputial diverticulum (por)

Female Genitalia & Associated Structures
        ovary
                ovulation fossa
                ovarian bursa
                corpus lutem
                ovarian proper ligament
        mesosalpinx
        uterine tube
                infundibulum
        uterus
                uterine horns
                uterine body
                intercornual ligament (bov)
                placentomes
        cervix
                external os of the cervix
                transverse folds of the cervix (bov)
                mucosal prominences (por)
        vulva
                dorsal & ventral commissures
                clitoris
                        clitoral fossa
        vestibule
        vagina
        urethra
                urethral orifice
                        suburethral diverticulum (bov)
        ovarian a.
        ovarian v.
        (uterine a.)

Mammary Gland Structures
        medial suspensory ligament
        lateral laminae
        external pudendal vessels
                venous ring
        subcutaneous abdominal ("milk") veins = cranial & caudal superficial epigastric vv.
        supernumerary teats
        teat orifice
        papillary duct
        lactiferous sinus
                teat sinus
                gland sinus
                lactiferous ducts
        mammary lymph node/superficial inguinal lymph node

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Instructor Commentary:

Several structures have different names for anatomists and clinicians or animal scientists. The ductus deferens of anatomy is often called vas deferens in the clinic but anatomists restrict use of the term vas to vessels. The clinical term oviduct is replaced by uterine tube in the anatomical literature and in human medicine the term tubal ligation is often used.

In common usage the term testicle refers to the testis plus the epididymis and the first part of the ductus deferens. In short, the testicle is what is removed by castration. Since cryptorchid castration is common in horses, differentiation of right and left testicles is important when only one descended testicle is found so that the surgeon knows where to look for the undescended testicle. By identifying the epididymis on the lateral side, ductus deferens on the medial side and the tail of the epididymis caudally, a testicle can be oriented so that left v. right can be determined.

The retractor penis muscle is of little functional significance in the male horse but in the bull and boar it attaches distal to distal loop of the penile sigmoid flexure and it is responsible for pulling the extended penis into the S shaped curve, the sigmoid flexure. A slaughterhouse steer penis can be used to demonstrate the action of the retractor muscle by holding the upper part of the penis firm on a table while pulling the retractor muscle with the other hand. Clinically, a pudendal nerve block will relax the retractor penis muscle and allow the penis to drop out of the prepuce for examination and treatment.

The mesosalpinx is the mesentery of the uterine tube. It has a free border known as the antimesosalpinx. The ovarian bursa is a space between the mesentery of the ovary (mesovarium) and the mesosalpinx. The opening of the ovarian bursa is tiny in carnivores but an examiner can pass several fingers into the bursa of mare, cow or sow.

The urethral orifice marks the junction of the vestibule with the vagina. Ruminants and the sow have a suburethral diverticulum ventral and caudal to the urethral orifice. When passing a urethral cannula this diverticulum should be filled with a finger to prevent the cannula from entering the diverticulum and to guide it into the urethral orifice.

The bovine cervix has several transverse rings that make passage of an AI (artificial insemination) pipet difficult but no such structures are found in the mare. The sow cervix is elongated and has numerous mushroom shaped mucosa prominences. Note: the penis of the ram and billy goat has a long thin urethral process that was thought to assist the entry of semen into the cervical canal during mating but experimental removal of the urethral process does not affect the rate of conception..

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Dissection Images:

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