Macro- and Microstructure of the Superior Cervical Ganglion in Dogs, Cats and Horses during Maturation

Abstract

The superior cervical ganglion (SCG) provides sympathetic input to the head and neck, its relation with mandible, submandibular glands, eyes (second and third order control) and pineal gland being demonstrated in laboratory animals. In addition, the SCG’s role in some neuropathies can be clearly seen in Horner’s syndrome. In spite of several studies published involving rats and mice, there is little morphological descriptive and comparative data of SCG from large mammals. Thus, we investigated the SCG’s macro- and microstructural organization in medium (dogs and cats) and large animals (horses) during a very specific period of the post-natal development, namely maturation (from young to adults). The SCG of dogs, cats and horses were spindle shaped and located deeply into the bifurcation of the common carotid artery, close to the distal vagus ganglion and more related to the internal carotid artery in dogs and horses, and to the occipital artery in cats. As to macromorphometrical data, that is ganglion length, there was a 23.6% increase from young to adult dogs, a 1.8% increase from young to adult cats and finally a 34% increase from young to adult horses. Histologically, the SCG’s microstructure was quite similar between young and adult animals and among the 3 species. The SCG was divided into distinct compartments (ganglion units) by capsular septa of connective tissue. Inside each ganglion unit the most prominent cellular elements were ganglion neurons, glial cells and small intensely fluorescent cells, comprising the ganglion’s morphological triad. Given this morphological arrangement, that is a summation of all ganglion units, SCG from dogs, cats and horses are better characterized as a ganglion complex rather than following the classical ganglion concept. During maturation (from young to adults) there was a 32.7% increase in the SCG’s connective capsule in dogs, a 25.8% increase in cats and a 33.2% increase in horses. There was an age-related increase in the neuronal profile size in the SCG from young to adult animals, that is a 1.6-fold, 1.9-fold and 1.6-fold increase in dogs, cats and horses, respectively. On the other hand, there was an age-related decrease in the nuclear profile size of SCG neurons from young to adult animals (0.9-fold, 0.7-fold and 0.8-fold in dogs, cats and horses, respectively). Ganglion connective capsule is composed of 2 or 3 layers of collagen fibres in juxtaposition and, as observed in light microscopy and independently of the animal’s age, ganglion neurons were organised in ganglionic units containing the same morphological triad seen in light microscopy.

Detailed Anatomy of the Cranial Cervical Ganglion in the Dromedary Camel (Camelus dromedarius)

“…In conclusion, there was no variation regarding topography of the dromedary CCG among the specimens, in spite of typical variations in (Fioretto et al, 2007), dog (Evans, 1993) Ventral to the atlanto-occipital joint Horse (Getty, 1975) Ventral to the atlas Roe deer, pig, cat (Pick, 1970) Ventral to the atlanto-axial joint Donkey Not recorded exactly White yak, yak, Angora goat, guinea pig, albino rat, dog (Mizeres, 1955) Communicating branch from the CCG to cranial nerve Species…”

“…On the other hand, some authors have stated that there is a positive correlation between body size and CCG length or size in the horse, cat, dog (Fioretto et al, 2007), and Angora goat. In contrast, we do not agree with such a correlation in the dromedary, which is in concordance with the findings of previous studies in guinea pig and roe deer.…”

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).…”