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

Abstract

Six liner measurements of constant cranial cervical ganglion (CCG), three inconstant main, first, second middle cervical ganglia (MG, MG1, MG2), and interganglionic branch (IGB) were taken to determine normal foetal growth rates and patterns of cervical sympathetic trunk (CST) components in different gestational ages. Forty sheep foetuses of both sexes aged from 60 to 140 days were divided into four groups and 80 sides of foetuses were examined under a stereomicroscope using a digital calliper. Following findings were obtained: 1) There was no significant difference for the values between sex and body side among all age groups, although sex and laterality differences in CST length and laterality differences in IGB total length and MG1 width were found regardless of age groups. 2) Correlations between dimensions of CST components and crown-rump length (CRL) were always positive during foetal period and decreased with increasing foetal age. 3) The highest growth rate in CST components in foetal sheep took place in the youngest age group because of rapid growth rates in lengths of IGB and CCG. Based on these detailed findings, comparative prenatal growth rates and patterns of animal organs and body, embryological and histological data as well as neurovertebral relationships among cervical parts of sympathetic trunk, spinal cord, and vertebral column were discussed and compared with previous studies. Although allometric growth of CST in relation to CRL was constant between foetal sheep and pig, there were specific characteristics in prenatal growth of CST components in foetal sheep which were different from those of foetal pig. It seems that only growth pattern in length of CST in sheep during foetal period follows the same growth pattern of CRL, body weight, and length of cervical parts of spinal cord and vertebral column.