Many of the studies conducted on the Biosatellite were repeats of experiments flown previously on the Cosmos 1887 mission. The results of those experiments were inconclusive because there was a delay in recovering the 1887 Biosatellite. Consequently, the experimental subjects had partially readapted to Earth gravity before postflight tests could be performed. The Rat Biospecimen Program included 42 experiments conducted by the U.S. on tissues from the flight rats. The goal of the program was to extend the investigations conducted aboard the Cosmos 1887 Biosatellite, with a shorter specimen recovery period. Methodologies used in Cosmos 1887 experiments were duplicated and extended in order to maximise comparability. Among these were studies of the effects of microgravity on various tissues such as the heart, lungs, small intestine, liver, muscle, bone, connective tissue and testes. Experiments were also carried out to determine the response of the immune and endocrine systems to space flight. Other studies were concerned with processes such as tissue repair and skeletal growth in the space environment. The primates flown on the spacecraft acted as experimental subjects for five studies that dealt with the effects of space flight on neurovestibular, behavioural, muscular, circadian rhythm and thermoregulation responses. Another experiment was performed without using biological subjects, to evaluate the radiation environment inside and outside the spacecraft. Primate experiments were conducted inflight on two male Macaca mulatta monkeys, named Zhakonya and Zabiyaka. These and control monkeys were implanted with several electrodes and sensors for recording physiological parameters. Subjects for the rat experiments were male specific pathogen free Wistar rats. The flight group and each of three control groups contained ten rats. Five of the rats in each group were surgically treated so that tissue repair in space could be studied. Apart from the Synchronous Control and the Vivarium Control experiments, another control was carried out on this mission. The rats in this third control group were placed in individual cages and suspended by their tails in a head-down position, so that the weight of the lower body was supported by the forelimbs. The objective was to remove static loads from the hindlimbs and thereby to simulate the fluid distribution that occurs in microgravity.