Biomaterial Database

Muscle at birth in mice selected for large and small body size. 1994

S C Brown, and N C Stickland

Department of Veterinary Basic Sciences, Royal Veterinary College, University of London, UK.

Selection for divergent body weight at 6 wk of age in the Q strain mouse has produced large (QL) and small (QS) mice which differ 2-fold in their adult body weight. The purpose of this investigation was to identify some of the cellular mechanisms which underlie the early divergence in size between the 2 lines. At birth, QL mice (for similar litter sizes) were 28% heavier and 6% longer than QS mice. This was reflected by measurements of longitudinal bone length which were greater in QL (tibia 6.2%, humerus 4.2%) compared with QS mice. Fibre number was found to be 18 and 17% greater in the biceps brachii and soleus muscles respectively of the QL mice. It was concluded that this was not a consequence of any alteration in the ratio of developing secondary to primary myofibres in either muscle. Fibre cross-sectional areas were only significantly different between the QL and QS for the soleus muscle, which might be explained by the relatively greater divergence in the length of its supporting bone (tibia) between the QL and QS compared with the humerus. Estimates of nuclear number showed that there were significantly more nuclei in biceps brachii muscle of QL than in the QS mice which could be attributed to the difference in fibre number, although no such differences were found for the soleus muscle. There was no apparent alteration in the proportion of nuclei found within the fibres of the biceps muscle. Overall the results indicate that selection in this situation has acted through the normal cellular processes of growth.

UI	MeSH Term	Description	Entries
D008098	Litter Size	The number of offspring produced at one birth by a viviparous animal.	Litter Sizes,Size, Litter,Sizes, Litter
D008815	Mice, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.	Inbred Mouse Strains,Inbred Strain of Mice,Inbred Strain of Mouse,Inbred Strains of Mice,Mouse, Inbred Strain,Inbred Mouse Strain,Mouse Inbred Strain,Mouse Inbred Strains,Mouse Strain, Inbred,Mouse Strains, Inbred,Strain, Inbred Mouse,Strains, Inbred Mouse
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D001835	Body Weight	The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.	Body Weights,Weight, Body,Weights, Body
D001947	Breeding	The production of offspring by selective mating or HYBRIDIZATION, GENETIC in animals or plants.	Breedings
D002467	Cell Nucleus	Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Cell Nuclei,Nuclei, Cell,Nucleus, Cell
D006811	Humerus	Bone in humans and primates extending from the SHOULDER JOINT to the ELBOW JOINT.	Humeri,Greater Tubercle,Humeral Greater Tuberosity,Humeral Lesser Tuberosity,Lesser Tubercle,Olecranon Fossa,Olecranon Fossi,Greater Tubercles,Greater Tuberosities, Humeral,Greater Tuberosity, Humeral,Humeral Greater Tuberosities,Humeral Lesser Tuberosities,Lesser Tubercles,Lesser Tuberosities, Humeral,Lesser Tuberosity, Humeral,Tubercle, Greater,Tubercles, Greater
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000831	Animals, Newborn	Refers to animals in the period of time just after birth.	Animals, Neonatal,Animal, Neonatal,Animal, Newborn,Neonatal Animal,Neonatal Animals,Newborn Animal,Newborn Animals
D013977	Tibia	The second longest bone of the skeleton. It is located on the medial side of the lower leg, articulating with the FIBULA laterally, the TALUS distally, and the FEMUR proximally.	Tibias