A system of canals in semilunar menisci

SUMMARY Semilunar menisci of young calves, and infants and young children were examined with the scanning electron microscope and the light microscope. Canal-like structures were noted opening onto the surface of the menisci. After filling the joints with Indian ink, ink was noted within canal-like structures deep in the substance of the tissue. The canals may play a part in the transport of fluid within the meniscus, or may carry nutrients from the synovial fluid or the blood vessels to the avascular sections of the meniscus. The semilunar menisci are fibrocartilaginous struc-tures, which play an important part in the function of the knee: they stabilise the joint and transmit load from the femur to the tibia. They are thought to facilitate lubrication.2 It is known that developing menisci are different from those of adolescents and adults: they contain more vessels, are much more cellular, and may have greater reparative pro-perties. A number of workers have studied the surface of menisci using the scanning electron microscope: the femoral and tibial surfaces are similar and showk ridges and grooves running predominantly in the long axis of the tissue,4 which may be due to shrinkage. ' Humps have been observed on the surface of the menisci of children. 7 In this study we have used the scanning electroni microscope and the light microscope to examine the surface of menisci of young children and new born calves. We present evidence for the existence of a system of canaliculi linking the surface with the depths of the tissue. Materials and methods Human knee joints were obtained from two stillborn individuals and after death from subjects aged 3 weeks, 1 year, 3 years. and 6 years. After examina-tion of some of the specimens the possibility of postmortem artefactual changes was considered. Consequently, knee joints of six near term feta