Asymmetric post‐natal development of superior cervical ganglion of paca (Agouti paca)

Abstract

Functional asymmetry has been reported in sympathetic ganglia. Although there are few studies reporting on body side-related morphoquantitative changes in sympathetic ganglion neurons, none of them have used design-based stereological methods to address this issue during post-natal development. We therefore aimed at detecting possible asymmetry-related effects on the quantitative structure of the superior cervical ganglion (SCG) from pacas during ageing, using very precise design-based stereological methods. Forty (twenty left and twenty right) SCG from twenty male pacas were studied at four different ages, i.e. newborn, young, adult and aged animals. By using design-based stereological methods the total volume of ganglion and the total number of mononucleate and binucleate neurons were estimated. Furthermore, the mean perikaryal volume of mononucleate and binucleate neurons was estimated, using the vertical nucleator. The main findings of this study were: (1) the right SCG from aged pacas has more mononucleate and binucleate neurons than the left SCG in all other combinations of body side and animal age, showing the effect of the interaction between asymmetry (right side) and animal age, and (2) right SCG neurons (mono and binucleate) are bigger than the left SCG neurons (mono and binucleate), irrespective of the animal age. This shows, therefore, the exclusive effect of asymmetry (right side). At the time of writing there is still no conclusive explanation for some SCG quantitative changes exclusively assigned to asymmetry (right side) and those assigned to the interaction between asymmetry (right side) and senescence in pacas. We therefore suggest that forthcoming studies should focus on the functional consequences of SCG structural asymmetry during post-natal development. Another interesting investigation would be to examine the interaction between ganglia and their innervation targets using anterograde and retrograde neurotracers. Would differences in the size of target organs explain ganglia structural asymmetry?

Stereological and Allometric Studies on Neurons and Axo-Dendritic Synapses in Superior Cervical Ganglia

“…This ganglion is also very closely adjacent to the hypoglossal nerve. In all species studied, the SCG was white in color and roughly spindle shaped, independently of the animal age (Abrahão et al, 2009;Coppi and Loesch, 2011;Fioretto et al, 2007Fioretto et al, , 2011Ladd et al, 2012;Loesch et al, 2010;Melo, 2009;Ribeiro, 2006;Ribeiro et al, 2004;Toscano et al, 2009). s0025 2.1.2 Macromorphometry p0040 The macromorphometric aspects of the SCG-length, width, and thickness-vary greatly according to the animal species and animal age Macrostructure of the SCG of an adult dog (A), cat (B), and horse (C).…”

“…Recognizing this gap in the literature, over the past 10 years, we have investigated the quantitative structure of SCG from a broad range of mammals, including both small laboratory and exotic rodents such as rats and capybaras (Loesch et al, 2010;Ribeiro et al, 2004), pacas (Abrahão et al, 2009;Au2 Melo, 2009), guinea pigs (Toscano et al, 2009), and preás (Ladd et al, 2012) and also domestic large mammals such as dogs and cats (Fioretto et al, 2007), sheep (Fioretto et al, 2011), and horses (Fioretto et al, 2007;Loesch et al, 2010;Ribeiro et al, 2004). In our own published work, the quantitative assessment of SCG structure-neurons, sypnases, neuropil, vessels, and connective tissue among others-was conducted using 3D technology employing the design-based stereology.…”

“…The SCG of rats, guinea pigs, preás, cutias, pacas, capybaras, sheep, dogs, cats, and horses is located near the base of the skull and deeply into the bifurcation of the common carotid artery, in the origin of the external and internal carotid arteries close to the distal ganglion of the vagus nerve (Abrahão et al, 2009;Coppi and Loesch, 2011;Fioretto et al, 2007Fioretto et al, , 2011Gabella, 2004;Hedger and Webber, 1976;Ladd et al, 2012;Loesch et al, 2010;Melo, 2009;Ribeiro, 2006;Ribeiro et al, 2004;Toscano et al, 2009) (Fig. 2.1).…”

“…Image and legend extracted from Fioretto et al (2007). B978-0-12-800179-0.00002-7, 00002 IRCMB, 978-0-12-800179-0 investigated, that is, rats, guinea pigs, preás, rabbits, cutias, pacas, capybaras, cats, dogs, sheep, horses, and camels (Abrahão et al, 2009;Coppi and Loesch, 2011;Fioretto et al, 2007Fioretto et al, , 2011Kabak, 2007;Ladd et al, 2012;Loesch et al, 2010;Melo, 2009;Najafi and Nejati, 2009;Ribeiro, 2006;Ribeiro et al, 2004;Sheng et al, 1998;Toscano et al, 2009) In mammals, the SCG provides sympathetic innervation to the head and neck as well as to the mandible, submandibular and pineal glands, cephalic blood vessels, choroid plexus, eye, carotid body, salivary, and thyroid glands (Arbab et al, 1986;…”

“…s0045 2.2.2 SCG neurons p0080 SCG neurons are generally spindly shaped-or circular-and readily distinguishable due to their large size, clear nucleus, and the evident nucleolus. Ganglion neuron profiles are normally surrounded by one to two intraganglionic capillaries (in this case they are named intraunit capillaries) as well as by one to three glial cell nuclei (satellite cells) whose processes formed the ganglion neuron glial capsule (Abrahão et al, 2009;Coppi and Loesch, 2011;Fioretto et al, 2007Fioretto et al, , 2011Ladd et al, 2012;Loesch et al, 2010;Melo, 2009;Toscano et al, 2009) (Fig. 2.4).…”