关键词: 江豚, 脊髓, 胸外侧核, 腰尾外侧核, 细胞构筑

Abstract: Based on three fresh specimens caught accidently from the Yangtze River near Nanjing in the spring of 1984，a neuroanatomical，histological and cytoarchitural investigation of the spinal cord of Finlees perpoise(Neophocaena phocaenoides)had brought us a good result．Frozen sections of the spinal cord of one animal (NJNU 0149) were cut at 70 microns．The nerve cells were stained with 1% thionine inalcohol.
Forty- four pairs of the spinal nerves were found in gross anatomy.The descriptive formula of the spinal cord of all the three specimens was 8 cervical,13 thoracic and 23lumbocaudal segments.
there are some differences in characteristics of the general features and transverssecticns of the spinal cord between Finless porpoise and Eubalaena glacailis．Balaenoptera physalus and phocoena．These differences are distribution in this article．
Though the nerve cells are poor in the gray matter，their distribution was regular,
According to the variation on the nervecelltype s，their feature, their deasity．their
distribution and cytoarchitecture patterns．the author divided the gray matter into 10 layers．The layer division of Finless porpoise is similar to that of cats (R xed．1954)and other mammals．
The relation between some nucleus and layers in the gray matter was observed．The lateral cervical nucleus was located at the1ateral funiculus of cervical segments in the spinal cord．It contained four typesof nerve cells with island-like distribution and its structure was evidently similar to those in sperm whales (seki，1984)．
A specific cell group was located closely lateral to the dorsal horns of the thoracic
segments (8- 13)and lumbocaudal segments (1，6， 8 ，11，17，19)of the spinal cord．After the precise comparative anatomical and histological jnvestigations．the author found that most of those nerve cells were triangular，others were shuttle-shaped．They were beading-like in arran- gement or scattered．
The structure of the specific cel1 groups in the thoracic and lumbocaudal segments was thought to be corresponding tothe lateral Cervical nueleus．Thess findings were first noted in cetacea．therefore the author suggested that the specific cell groups in the thoracic and lumbocaudal segments may be named the lateral thoracical nueleus and ‘the lateral lumbocaudal nucleus’rsspectively． In the lateral thor- acical nucleusand the centripetalfiber of the nerve cell connecting with the V layer of dorsal hore was observed．Thosee.11 groups probablybelong to the spino—thoraco—thalamic relay systemor the spino-lumbocaudo-thalamic relay system just as the lateral cervical nucle—us does．

Key words: Finless perpoise, Neophocaena phocaenoides, Spinal cord．Lateral thoracic nucleus, Lateral, lumbocaudal mucleus, cytoarchitecture.