Morphology and development of the cervical part of the sympathetic trunk (pars cervicalis trunci sympathici) in the pig (Sus scrofa L.) during the prenatal period.

The aim of our experiment was to establish the morphological changes occurring in the cervical part of sympathetic trunk of the pig during its fetal development. The experiment was conducted on 38 swine fetuses, divided into three developmental groups. The investigated section in 6-11-week-old fetuses usually consisted of 3 ganglia. In the oldest age group only 2 ganglia appeared--the middle cervical ganglion was usually not observed. The statistical parameters referring to the cranial cervical ganglion (standard deviation, coefficient of variation) increase with the age of the fetus, suggesting that the greater part of the development occurs at the end of gestation. The investigated ganglion was negatively allometric in relation to body length during the whole of gestation. The most frequent arrangements of the cervicothoracic ganglia noted in the fetuses investigated were: [GCca + GTh1 + GTh2] on the left side of the body, and [GCca + (GTh1 + GTh2)] on the right.