Distribution and three-dimensional reconstruction of lymphatic vessels of the elbow joint capsule of rabbits
Yamashita, S.; Ohkubo, M.
Kaibogaku Zasshi. Journal of Anatomy 68(5): 513-521
1993
ISSN/ISBN: 0022-7722 PMID: 8279262 Document Number: 420773
Lymphatic vessels are believed to be distributed in the the depth of synovial membrane, but the details of this distribution remain to be fully elucidated. The synovial membrane is classified in part on the basis of histological characteristics, even in the same joint capsule, into three fundamental types: adipose type, areolar type, and fibrous type. In addition, the adipose and areolar types are involved in the absorption of synovial fluid. In this study, the distribution of lymphatic vessels was investigated with special reference to histological structure of the synovial membrane. The materials were prepared from 11 elbow joint capsules of male 8 rabbits weighing 2-3 kg. Five specimens were stained with silver nitrate, and the remainder were stained with trichrome. All of the materials were serially sectioned and observed by light microscopy. Three-dimensional reconstructions of lymphatic vessels were performed using Cosmozone 2SA software (Nikon Co.) with a PC-9800 series microcomputer (NEC Co.) When the joint capsule is divided into synovial and fibrous layers in accordance with the Nomina Histologica Japonica, the fibrous layer is frequently connected with the epimysium of neighboring muscles. The synovial and fibrous layers are occasionally continuous with each other, without a distinct boundary. The number of lymphatic vessels in the synovial layer is small, and they originate in the vicinity of the border of the fibrous layer and pass over into the lymphatic vessels of the fibrous layer. Many lymphatic vessels were found in the fibrous layer, the majority of which come from the epimysium or perimysium close to the outer surface of the fibrous layer. There is a direct correlation between histological characteristics of the synovial layer and the pattern of distribution of lymphatic vessels on the caudal half of the elbow joint capsule. Both in the greater part of the medial wall and in the lateral margin of the lateral wall of the caudal half of the joint capsule, many lymphatic vessels coming from the epimysium or perimysium are present in the fibrous layer. The synovial layer, from which lymphatic vessels originate, is an area composed of the areolar type, the fibrous type and even the adipose type. The distribution of lymphatic vessels on the rostral half of the elbow joint capsule do not necessarily coincide with the histological characteristics of the synovial layer. Lymphatic vessels are few or even absent in the adipose-type synovial layer of the lateral wall, whereas they are abundant in areolar and fibrous-type synovial layers of the centromedial portion. The lymphatic distribution of the joint capsule is morphologically divided into three types. Type 1: most lymphatic vessels show a simple dendriform ramification. At the termination of a ramus, the initial lymphatic vessels are present, which originate from the synovial layer just above the fibrous layer, and most rami correspond to collecting lymphatic vessels in the fibrous layer. Type 2: there are only a few simple plexiform lymphatic vessels passing from the synovial layer to the fibrous layer. Type 3: a simple tubular system originating from the adipose-type synovial layer. The lymphatic vessels in this type show a relatively long course along the blood vessels in the synovial layer, and then go over into the lymphatic vessels of the fibrous layer.