Biomaterial Database

Postnatal development of cat hind limb motoneurons. III: Changes in size of motoneurons supplying the triceps surae muscle. 1988

B Ulfhake, and S Cullheim

Department of Anatomy, Karolinska Institute, Stockholm, Sweden.

The postnatal changes of neuronal dimensions were studied in cat triceps surae motoneurons intracellularly labeled with horseradish peroxidase. Systematic correlations were observed in the analysis of single dendrites at each studied stage, from birth to 44-46 days post natum (d.p.n.) age, between size parameters intrinsic to the dendrites as the diameter of a 1st-order dendrite, the combined dendritic length, the dendritic membrane area, and the degree of branching. Some variability among samples was evident in each studied age group. The correlations were, however, sufficiently close to permit indirect estimations of both combined dendritic length and dendritic membrane area for larger samples of neurons from data on dendritic stem caliber. The total postnatal increase in dendritic membrane area was, on the average, 400%, i.e., from close to 100 X 10(3) microns2 to about 500 X 10(3) microns2. The corresponding increase in soma area amounted to 100%. Analysis revealed that there was a time lag between the increase in somatic and dendritic size. Thus, adult somatic dimensions were attained at age 44-46 d.p.n.; however, at this stage, the mean total dendritic membrane area was only about half of the adult value. The postnatal increase in size appeared to vary among neurons, yielding a wider neuronal size spectrum in the adult cat than that observed in kittens. The measured increase in size corresponded to a calculated average addition of dendritic membrane area of 3700 microns2/day from birth to 22-24 d.p.n. and from that stage to 44-46 d.p.n. of 2700 microns2 per day. Likewise, the increase in combined dendritic length could initially be as large as 1 mm/day down to 0.4 mm/day between 22-24 and 44-46 d.p.n., with a mean growth during the first 44-46 d.p.n. of 0.5 to 0.6 mm/day. The ratios of daughters to parent branch diameters (sigmadd1.5: dp1.5) and the dendritic trunk parameter (sigma d1.5) recorded along the proximodistal dendritic path distance revealed transient changes that might impact on the electrotonic properties of the dendrites during postnatal development. Computations from the measured changes in dendritic branch lengths and calibers indicated that if membrane and internal resistivity remain unaltered during postnatal development, the dendritic domain is electrotonically more compact in the newborn kitten than in the adult cat.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003712	Dendrites	Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.	Dendrite
D006614	Hindlimb	Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)	Hindlimbs
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
D013116	Spinal Cord	A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.	Coccygeal Cord,Conus Medullaris,Conus Terminalis,Lumbar Cord,Medulla Spinalis,Myelon,Sacral Cord,Thoracic Cord,Coccygeal Cords,Conus Medullari,Conus Terminali,Cord, Coccygeal,Cord, Lumbar,Cord, Sacral,Cord, Spinal,Cord, Thoracic,Cords, Coccygeal,Cords, Lumbar,Cords, Sacral,Cords, Spinal,Cords, Thoracic,Lumbar Cords,Medulla Spinali,Medullari, Conus,Medullaris, Conus,Myelons,Sacral Cords,Spinal Cords,Spinali, Medulla,Spinalis, Medulla,Terminali, Conus,Terminalis, Conus,Thoracic Cords
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D024510	Muscle Development	Developmental events leading to the formation of adult muscular system, which includes differentiation of the various types of muscle cell precursors, migration of myoblasts, activation of myogenesis and development of muscle anchorage.	Myofibrillogenesis,Myogenesis,Muscular Development,Development, Muscle,Development, Muscular