Chemical sympathectomy by 6-OH dopamine during fetal life results in inguinal testis through altering cremasteric contractility in rats

Calcitonin gene-related peptide stimulates mitosis in the tip of the rat gubernaculum in vitro and provides the chemotactic signals to control gubernacular migration during testicular descent

BACKGROUND/AIMS

We investigated whether calcitonin gene-related peptide (CGRP) released from sensory genitofemoral nerve branches could stimulate rodent gubernacular growth and provide chemotactic signals for directing inguinoscrotal gubernaculum migration in vitro.

MATERIALS AND METHODS

Neonatal rat gubernacula containing a developing cremaster sac (n = 60) were removed at days 0, 2, 4, 6, 8, and 10 (n = 10 per age; n = 5 per experimental group) and placed in organ culture for 24 hours with or without added CGRP (720 nmol/L). The gubernacula were stained for bromodeoxyuridine (BrdU) immunohistochemistry. Cells were counted (3 x 100 cells) in the mesenchymal tip of the gubernaculum to find the percentage of BrdU uptake. A further group of neonatal rat gubernacula (n = 21 per group) were placed in organ culture on an agar platform with 5 agarose beads soaked in either PBS or 10(-6) mol/L CGRP placed approximately 0.8 to 1 mm on each side of the tip of the cremaster sac. After 72 hours, the position of the gubernaculum was compared with its starting position and any deviation measured.

RESULTS

Exogenous CGRP caused a significant increase in BrdU uptake in the tip of the gubernaculum in 0-day-old rats compared with control cultures. Two-way analysis of variance in the cellular proliferation pattern between gubernacula cultured +/- CGRP between 0 and 10 days showed a significant difference (P < .001). The cultures containing CGRP-impregnated beads caused significant (P < .01) deviation of the tip of the gubernaculum toward the beads, whereas the controls demonstrated no net movement of the tip.

CONCLUSIONS

These studies demonstrate that mitosis in the tip of the rat gubernaculum is significantly increased in response to CGRP in vitro. Also, CGRP may provide chemotactic signals to control inguinoscrotal gubernacular migration in the rat.

Does chemical sympathectomy alter the ontogeny of gubernacular migration in vivo?

BACKGROUND

Testicular descent occurs in several stages, but the exact mechanism remains obscure. Sympathetic nerves have been proposed to have a role by a possible action on developing cremaster muscle, following observations of sympathetic dysfunction in cremaster from boys with cryptorchidism. This study aimed to see if chemical sympathectomy affected testicular descent in rats.

METHODS

Sprague-Dawley dams were injected with 6-hydroxydopamine (days 15-19; 75 microg/kg) or control vehicle alone, and male pups examined at 0 to 10, 20, 30, and 60 days of age. The length of the processus vaginalis was measured and sections taken for histology.

RESULTS

No difference in processus vaginalis growth was found between experimental and control groups, both macro- and microscopically. Chemical sympathectomy was confirmed by loss of adrenergic fibres in the adrenal cortex of experimental, but not control, animals.

CONCLUSIONS

These studies suggest that sympathetic innervation is not an important part of testicular descent in the rat but does not exclude a pathologic role in undescended testes or effects in humans only.

Sensory, motor somatic, and autonomic neurons projecting to the porcine cremaster muscle

The location of sensory, somatic, and autonomic neurons projecting to the pig cremaster muscle (CM) was studied by means of the retrograde neuronal tracer Fast Blue (FB) technique. FB was randomly injected in the left CM of four impuberal pigs and serial sections of sensory and autonomic ganglia and spinal cord were examined under a fluorescence microscope. Additionally, some indications about the number and size of labeled neurons were given. Sensory pseudounipolar somata were located ipsilaterally in the L2-L6 and S1-S2 dorsal root ganglia, their total number ranging between 125 and 194, their mean diameter between 24 and 89 microm. Somatic multipolar motoneurons were located ipsilaterally in the L2-L4 neuromeres of the spinal cord, their total number ranging between 53 and 169, their mean diameter between 29 and 53 microm. Autonomic multipolar paravertebral ganglia neurons were located ipsilaterally from L1 to S4 and contralaterally from L2 to S2. Their total number ranged from 2,015 to 3,067 and their mean diameter between 25 and 55 microm. The multipolar caudal mesenteric ganglia neurons were located bilaterally, their total number ranging between 14 and 1,408 and their diameter from 22 to 39 microm. In two subjects only, multipolar neurons were also found ipsilaterally in the microganglia of pelvic plexus (2 and 13 neurons). Their mean diameter ranged between 28 and 54 microm. Our study documented that the CM-projecting neurons were located at different neural levels, with a predominance in the autonomic ganglia.