Developmental Morphology and Topography of the Components of the Cervical Sympathetic Trunk in Sheep (Ovis aries) During the Fetal Period

Abstract

The objective of this study was to clarify the typical architecture and morphological variations of cervical sympathetic trunk (CST) in sheep during fetal period. Components of CST were examined on both sides of 40 male and female sheep fetuses aged from 60 to 140 days under a stereomicroscope. Skeletotopy and frequency of presence of cranial cervical ganglion (CCG), syntopy of cervical ganglia, and composition and topography of vagosympathetic trunk were consistent among specimens whereas the shape of cervical ganglia, the skeletotopy and number of three middle cervical ganglia (MG), and the frequency of communicating branches of CCG to the first cervical spinal nerve exhibited differences during fetal period. A reduction in the number of MG and the caudal movement of main MG were noted by increasing fetal age. Based on these detailed findings, comparative and developmental anatomy and evolutionary changes are discussed and compared with previous studies. The number of MG, skeletotopy of CCG and main MG, the number and range of communicating branches of CCG to spinal nerves, and the association of vagus and sympathetic nerves in fetal sheep were fundamentally different from those of mostly reported species. These results suggest that data obtained from CST of fetal sheep are significantly different from those obtained from humans, and it is problematic to apply them to humans because of the more cranial position of CCG, very narrow contribution of CCG to spinal nerve, absence of the vertebral ganglion, existence of multiple MG, and no communicating branches from MG to spinal nerves. Anat Rec, 300:2250-2262, 2017. © 2017 Wiley Periodicals, Inc.

Quantitative prenatal growth of the cervical sympathetic trunk components in sheep (Ovis arise) during the foetal period

“…Constant cranial cervical ganglion (CCG) and three inconstant MG, MG1, MG2 and their interganglionic branch (IGB), as described by Nourinezhad et al [11], of 10% formalin fixed foetuses were measured under a stereomicroscope (Nikon, SMZ800, Japan) using a digital calliper (150 mm Mitutoyo, Japan) to an accuracy of 0.05 mm by a single researcher (the first author) and three times as follows: 1) The highest length (craniocaudal), width (dorsoventral), and thickness (mediolateral) of the ganglia. 2) The length (craniocaudal) of each IGB was measured.…”

“…Analyses of organ growth rates during prenatal development have brought to light definite growth tendencies and patterns and such a growth of one part of the body often appears to be quit out of step with the growth of another part, or of the organism as whole. Among organs, morphometrical changes of sympathetic trunk components during various growth phases of animals and humans foetuses have been neglected in developmental research because of its complex morphology, although our previous studies of sympathetic trunk and paravertebral ganglia have been conducted to clarify further knowledge about their detailed morphological architectures in adult dromedary camel, and bovine [9,10] or developmental anatomy in sheep during foetal period [8,11]. These studies indicate significant variations were present between animals and humans and their variations explained in terms of comparative anatomy, embryonic development, and evolutionary changes.…”