Dissection of Pelvic Autonomic Ganglia and Associated Nerves in Male and Female Rats

This video will show the dissection technique and relevant anatomical landmarks for the major pelvic ganglion and associated autonomic nerves in the male and female rat. The first dissection is shown for the left side of a male rat immediately postmortem. Access the abdomen and pelvis through a ventral midline incision.

Gently move the abdominal organs to one side using forceps or cotton tipped applicators. Note the location of the ventral lobes of the prostate gland and the urinary bladder. Move the seminal vesicle to the contralateral side.

Cut the vas deferens to provide better access to the area overlying the ganglion. From this point of the dissection, the tissue must not dry out so keep the tissue moist with physiological saline. To visualize the ganglion, carefully clear away tissues near and overlying the ganglion.

If necessary, use a retractor to keep the dissection field clear. Remove a nearby aggregate of adipose tissue and open the lateral fascia of the pelvis. Identify the pelvic nerve by visualizing the internal iliac vein and it's fine branch projecting towards the major pelvic ganglion and the bladder.

This branch runs parallel to and sometimes embedded within the pelvic nerve then traverses the ganglion. Gently place fine tipped angled forceps under the pelvic nerve and slide the forceps along to free it from surrounding tissue. It may also be possible to isolate the pelvic nerve from the small vessel running parallel to it.

Identify the cavernous nerve by following the pelvic nerve to its junction with the ganglion then follow the cavernous nerve as it travels across the prostate and then caudally towards the cavernous bodies of the penis. Identify where the hypogastric nerve joins the ganglion at this cranial edge after traveling alongside the ureter. Identify the major pelvic ganglion and confirm the location of each major nerve.

Identify the accessory nerves at the ventral edge of the ganglion projecting towards the urinary and reproductive tracts. To remove the major pelvic ganglion with its associated nerves, gently slide forceps between the ganglion and the underlying prostate gland being careful not to puncture the thin capsule of the prostate. Clear any final connections with surrounding tissues then cut each nerve.

Move the ganglion with its nerves to the appropriate solution for your experiment and confirm that each of the main nerves are intact. The second dissection is shown for the left side of a female rat immediately postmortem. Gently move the abdominal organs to one side noting the location of the uterine horn, urinary bladder and rectum.

Cut the ovarian and uterine vessels and retract the uterine horn. Enter the peritoneal space and gently clear away an aggregate of adipose tissue located near the uterine cervix. Identify the lateral wall of the uterine cervix just caudal to its junction with the uterine horns.

This region is the primary landmark for defining the major pelvic ganglion location on the animal's rostrocaudal axis. Carefully remove any tissue that impedes complete view of the neural structures while avoiding damage to major vessels. Identify the pelvic nerve by finding the internal iliac vein and its fine branch projecting towards the major pelvic ganglion and the bladder.

This branch runs parallel to and sometimes embedded within the pelvic nerve then transverses the ganglion. Identify the hypogastric nerve where it joins the ganglion at its cranial edge after traveling alongside the ureter. Identify the cavernous nerve by following the pelvic nerve to its junction with the ganglion then follow the cavernous nerve as it travels caudally along the lateral wall of the cervix towards the vagina.

The accessory nerves are difficult to see but project from the medial aspect of the major pelvic ganglion. Finally, identify the major pelvic ganglion and confirm the location of each major nerve. To remove the major pelvic ganglion with its associated nerves, gently slide forceps between the ganglion and the underlying cervix and disrupt any connections between the ganglion and the cervix.

Clear any final connections with surrounding tissues for the lengths of nerves required for the experiment then cut each nerve. Move the ganglion with its nerves to the appropriate solution for your experiment and confirm that each of the main nerves are intact. An example of the major pelvic ganglion structure is illustrated here showing several features of formaldehyde-fixed ganglia using conventional immunohistochemistry.

This image shows the entire major pelvic ganglion with its associated nerves visualized as a full thickness whole mount. This image shows a cryosection immunolabeled to demonstrate noradrenergic neurons by their expression of tyrosine hydroxylase. This image shows cholinergic neurons visualized by their expression of neuronal nitric oxide synthase.

In conclusion, this protocol and related schematics provide researchers interested in pelvic visceral function with the tools to identify and dissect the major pelvic ganglion in male and female rats. These skills can be applied to many types of in vitro and in vivo experimental manipulation.