American Journal of Anatomy

doi: 10.1002/aja.1001280201pmid: N/A

Sawin, P. B.; Fox, R. R.; Latimer, H. B.

doi: 10.1002/aja.1001280202pmid: 5420898

Significant sex and strain differences in correlation of bone, body and skeletal weights show significant localized effects of sex and strain and a combination of both. Individually they seem to lack biological meaning. However, when considered in relation to the ponderal correlations, of which they are a part, they fall into place at the distal ends of a graded linear correlation series, both within and between limbs; and similarly between mandible and sacrum, respectively, with each bone of both limbs. The pattern of these gradients reveals a linear decline in correlation of bones with distance (rule of neighborhood, Karl Pearson) in most cases, but the exceptions are such as can be related to the functions in which they cooperate. In this way they demonstrate at least two major unifying genetic influences. One associates sex and strain with locomotion and the other with the incipient upright investigative posture of the Lagomorphs (including the rabbit). The expected effect of sex on the pelvis is apparently not expressed by these ponderal measurements. The manner in which this correlation approach, based on well established genetic growth differences, converges with the phylogenetic and ontogenetic concepts of normal and abnormal growth of bone in limbs and cranio‐facial development suggests that a combination of correlation and epigenetic analysis would be helpful in establishing a sound genetic background for the newer biomechanic, functional matrix and architectonic approaches.

Fletcher, Thomas F.; Bradley, William E.

doi: 10.1002/aja.1001280203pmid: 5420899

In five cats, sacral dorsal rhizotomies were performed, alone or in conjunction with sympathetic nerve transections. Urinary bladders, collected 7, 10, or 30 days following the nerve transections, were sectioned and stained by the Holmes silver nitrate and the Nauta and Gygax methods and examined under the light microscope. Degenerative changes occurred in bladders of all the cats permitting an assessment of the appearance and distribution of vesical sensory endings. Degenerated myelinated axons and nerve terminals were found bilaterally in bladders, although they were more numerous ipsilateral to the transections. Within the muscle coat, degenerated endings were found in the perifascicular connective tissue, and less frequently, on the surface of muscle fascicles; endings were not seen among the muscle cells within a fascicle. Sensory endings were identified in the subserosa and lamina propria but not in transitional epithelium. Except for an occasional Paccinian corpuscle, encapsulated endings were not found. Afferent endings in the bladder appeared to be non‐encapsulated and without terminal fiber modifications.

Carmel, Peter W.

doi: 10.1002/aja.1001280204pmid: 4986961

Efferent projections of the ventral anterior (VA) thalamic nucleus were investigated in 20 monkeys. In half of these animals degeneration was traced following stereotaxic lesions in the magnocellular (VAmc) or parvocellular (VApc) portions of the nucleus. Chronic cell changes in the VA nucleus were studied following various cortical ablations in the remaining animals.

Jensh, Ronald P.; Brent, Robert L.; Barr, Mason

doi: 10.1002/aja.1001280205pmid: 5448489

This study was conducted to determine if there is a greater variation in fetal weight and/or placental weight among litters of rat fetuses than within a single litter. Three hundred and twenty‐seven litters comprising 1,979 fetal and placental weights were analyzed using analysis of variance within versus among litters. There was a definite litter effect, i.e., variation in fetal and placental weight was greater (p < 0.05) among litters than within litters. The variation in fetal and placental weights between litters became greater with increasing litter size. Experimentally limiting the litter size early in gestation does not reduce or eliminate the litter effect. This litter effect means that individual fetuses from several rat pregnancies cannot be considered to have come from a common universe and, therefore, the number of litters and their mean growth data are much more meaningful than the number of embryos in an experiment. When designing research programs in which embryonic and placental growth in rats are to be evaluated, it is more important to establish the experimental goal on the basis of the total number of litters rather than the total number of embryos per experimental or control group.

Bruns, Romaine R.; Gross, Jerome

doi: 10.1002/aja.1001280206pmid: 5420900

This paper presents a detailed description of the notochord and its covering layers in the tail of the premetamorphic bullfrog (Rana catesbeiana) tadpole.

Marien, G. J.; McFadden, K. D.

doi: 10.1002/aja.1001280207pmid: 5420901

A comparative study of the hemopoietic tissues and blood of non‐pregnant and pregnant rats of graded duration of gestation was undertaken and the results were compared with those obtained on postsplenectomized rats at similar stages of pregnancy. The number of megakaryocytes was determined in representative fields of the liver, spleen and bone marrow. Platelet counts were performed on blood collected from the venae cavae of these rats using a modified Rees‐Ecker technique.

Mahan, Parker E.; Anderson, Kenneth V.

doi: 10.1002/aja.1001280208pmid: 4316085

In analyzing the anatomy and physiology of sensory systems it is often necessary that one activate the particular system being studied with appropriate stimulation. In experiments where this is necessary, the stimulation presented should be specific to the sensory system under study. With the pain system, however, this is most difficult since most stimuli that activate pain pathways also activate other pathways such as those that mediate touch and pressure sensations. It is also helpful to have available a stimulation technique that can be used in both acute experiments and long term neurophysiological and behavioral experiments. For investigation of the anatomical substrates of pain perception, a technique has been developed for implantation of bipolar electrodes in the teeth of cats that permits one to stimulate the tooth pulp in acute or chronic preparations, and, thus, to activate a pain pathway exclusively and directly. This technique provides a stimulus that is readily quantifiable, easily controlled, entirely nociceptive in character, and which can be used in a wide variety of situations.

Thaemert, J. C.

doi: 10.1002/aja.1001280209pmid: 5420902

Atrioventricular nodal tissue was obtained from a two‐week‐old mouse heart which was fixed with phosphate‐buffered osmium tetroxide, embedded in Epon 812, serially sectioned for both light and electron microscopy and stained with uranyl acetate. From study of electron micrographic montages of the first 115 serial sections of the most inferior portion of the atrioventricular node it was determined that the intercellular spaces of this portion of the node contain fibrocytes, bundles of collagen fibrils, capillaries and a plexus of unmyelinated nerve bundles which are insheathed by Schwann cells. Relatively large nerve bundles divide to form smaller ones, the vesiculated nerve processes of which make intimate contact with the sarcolemmae of nodal cells. These neuromuscular contiguities, on the basis of the physical interrelationships of their respective vesiculated nerve processes and nodal cells, exist in various forms. They may be categorized as follows: (1) individual vesiculated nerve processes which dwell in sarcolemma‐lined tunnels or in culs‐de‐sac inside the nodal cells; (2) individual vesiculated nerve processes which lie within shallow or deep grooves on the surfaces of nodal cells; (3) vesiculated nerve processes which remain part of a small bundle while dwelling in a groove on the surface of an individual nodal cell or in grooves on the surfaces of two or more nodal cells; and (4) small individual bundles of vesiculated nerve processes and their Schwann cell investments which reside within sarcolemma‐lined tunnels inside nodal cells. These neuromuscular contiguities are fully described and their significance is discussed in relation to the present status of the nature and organization of the postganglionic ramifications of the autonomic nervous system within the conduction system of the heart.