摘要
鲸类的皮肤是适应完全水生而发生显著改变的器官之一。在现代生存的四类淡水豚中,只有白鱀豚Lipotes vexillifer的皮肤尚未研究。(1974)报道了拉河豚Pontoporia blainvillei、亚河豚Inia geoffrensis及恒河豚Platanista gangetica的皮肤构造。但他观察的只是眼周围的皮肤,对身体其他部分的皮肤尚缺了解。为此,我们研究了白鱀豚各部分皮肤及皮下层的组织学构造。
Specimens of skin and subcutaneous layer were taken from two Baiji(Lipotes vexillifer),2.0-2.18 m in length,collected from the lower reaches of the Changjiang River,and examined microscopically.As the study of the skin of three other representatives of the Platanistoidea(Co,1974)is confined to the periocular region,it seems appropriate to give an account on the skin and the subcutaneous layer of the Baiji.The basic structure of Lipotes skin,like that of marine odontocetes and whales,is clearly distinguished from the skin of other mammals.The epidermis was thickest(3.5 mm)at the tip of the snout and the abdomen,and thinnest(1.2-1.8 mm)around the eye.Nuclei were observed in all epidermal cells including those at the surface(PlateⅠ:3).Epidermal hypertrophy and encapsulated foreign bodies(PlateⅡ:12)were found in the specimens taken from the tip of the snout.The papillary layer of the dermis sends long projections to between corresponding rete ridges of the epidermis.In Lipotes,as the case in Pontoporia,Inia and Plata-nista,the irregular epidermal processes protrude into the basal part of the dermal papillae(PlateⅡ:7).In the skin of the thorax and the dorsum behind the blowhole there are approximately 14 and 21 papillae per mm2 respectively.As a consequence of the intense folding of the underside of the epidermis,the stratum basale(stratum germina-tivum)is much folded and occupies a large area relative to the area of skin surface.The area of the epidermal stratum basale per cm^(2)of outer skin was 7.5 cm^(2)at the thorax and 10 cm^(2)at the dorsum behind the blowhole.Laminated oval encapsulated receptors are abundant in the reticular layer of the snout and flipper.They may therefore have a tactile function.The setting temperature of the fat in the subcutaneous layer of the Baiji(Table 3)is lower than the average minimum water temperature in February in the Chang-jiang River.The low setting temperature of the fat protecting the dolphin against the setting of external layer of their body is an adaptation to the cold water environment in winter.The skin and the subcutaneous layer of the appendages of the Baiji is rather different from that of the body.The subcutaneous layer forming the inner core of the fins consists mainly of bundles of collagen fibers.All major arteries in the flipper,dorsal and caudal fins are located centrally within a peri-arterial venous retia and forming the counter current vascular bundle(PlateⅡ:10).In addition to these bundles there are separate superficial thick walled veins.This vascular arrangements play an effective role in controlling heat loss by counter-current exchange.The thickness of the skin and the subcutaneous layer of the Baiji from fifteen selected regions are shown in Table 1.According to the comparison of the periocular skin,the measurements of the skin of Lipotes are similar to that of Pontoporia,but different from that of Platanista and Inia(Table 4).
作者
周开亚
李悦民
Zhou Kaiya;Li Yuemin(Nanjing Normal College)
出处
《海洋与湖沼》
1981年第6期566-572,581-582,共9页
Oceanologia Et Limnologia Sinica
