American Journal of Anatomy

doi: 10.1002/aja.1001170201pmid: N/A

Gavin, J. B.

doi: 10.1002/aja.1001170202pmid: 5883187

Three types of macroscopic incisor abnormality were observed in Wistar rats examined post mortem. Most common was an altered relationship of the incisors to one another due to either fracture, elongation, rotation, malposition, or a combination of these factors affecting one or more incisors. Enamel hypoplasia was evident as opaque whitish blotches, bands or fine transverse striations. Other incisors showed an overall uniform pallor of the enamel. These abnormalities frequently affected the same animal or the same incisor. The associations between them were significant (P< 0.01). All the incisors of the intact group were normal and the incidence of abnormalities in hypophysectomized rats was not significantly higher (P > 0.05). However, of the thyroparathyroidectomized animals 56.8% had an abnormal incisor relationship, 28.4% showed discrete enamel defects and 23% showed enamel pallor. The incidence of all types of abnormality was higher in surgically thyroparathyroidectomized rats (P< 0.05) than in other groups. No significant differences were found between completely and incompletely thyroidectomized rats or between subgroups which received different drug treatments. These findings are discussed in relation to similar reports and hypotheses are advanced to explain the abnormalities. Parathyroid deficiency rather than thyroid deficiency appears the most important etiological factor.

Bulger, Ruth Ellen

doi: 10.1002/aja.1001170203pmid: 5883188

Kidney cell fine structure in the aglomerular fish, Opsanus tau, varies profoundly with different fixation procedures. An extensive system of cisternae, tubules and irregular‐shaped elements of smooth‐surfaced membranes are seen in the basal cytoplasm after fixation with 2% OsO4 buffered with s‐collidine. Permanganate fixation demonstrates these membranes as extensions of the basal plasmalemma. Mitochondria and homogeneous bodies surrounded by a single dense membrane lie in close association with the basal membranes. The apical cytoplasm contains an abundance of smooth‐surfaced elements whose morphology varies with the fixation procedure used. The fine structure of these cells is discussed with respect to that of other ion transporting tissues and with respect to the concept that basal infoldings are related to “water reabsorption”.

Brightman, Milton W.

doi: 10.1002/aja.1001170204pmid: 5883189

The electron lucent channels, about 200 Å‐wide, between the plasma‐lemmas of adjacent cell processes within the brain are true pericellular spaces along which ferritin molecules can move. The micelles, visualized electronmicroscopically, move through the spaces until they encounter an interglial fusion or its myelin counterpart. The interspace between glial processes is abruptly sealed by these inter‐membranous fusions or occasionally distended by a dense filler capable of trapping ferritin. The cerebral interspace is thus highly variable in width and content.

Simmons, David J.; Nunnemacher, Rudolph F.

doi: 10.1002/aja.1001170205pmid: 5883190

Following hemi‐resection of the rat distal femoral epiphysis with its growing epiphyseal cartilage, the cut surface of the cartilage is sealed‐off by trabecular bone and the cells fail to undergo further growth and maturation at that site. However, since the peripheral rows of cartilage cells survive and continue to proliferate, the cellular activity gradient causes the epiphyseal remnant to rotate about the fixed cut surface of the cartilage toward the amputated side. In these experiments, the degree of epiphyseal rotation following partial amputation was compared to the longitudinal growth of the contralateral intact femurs in normal and estrogen‐treated rats. While estrogen treatment retarded both the growth of intact femurs and epiphyseal rotation, the ratios of these growth measurements calculated at different time intervals following osteotomy (0–4, 4–7, 7–9 weeks) were identical to those of the control series. It was concluded that partial amputation per se had no demonstrable effect on the vitality of the surviving chondrocytes of epiphyseal cartilages; moreover, these cells were entirely responsive to the growth depressing action of estrogen.

Weber, Dennis

doi: 10.1002/aja.1001170206pmid: 5327452

Thin ground sections (4–10 μ) of rat incisor enamel were prepared in appropriate planes using a modified hand grinding technique. Phase microscopic observations of these sections confirmed the previously defined rod arrangement in the inner layer of enamel, and also demonstrated a high degree of structural orientation in the outer layer of enamel. The initial layer of enamel formed was found to present a morphologic picture which has not been previously defined: a series of inter‐connected pillars of enamel on an elevated base which has a “fish net” appearance in tangential section.

Duffy, P. E.; Menefee, M.

doi: 10.1002/aja.1001170207pmid: 5883191

The median eminence of the rabbit has been studied electron microscopically and the neurosecretory granules in the nerve terminals of the external layer were shown to be smaller and have a denser central core than the granules composing Herring bodies which are generally larger and have a paler core which is finely granular or vesicular. It was proposed that the small dense granules, which may represent neurosecretory substances destined to reach the pars distalis via portal veins, reach the nerve terminals in the external layer via certain dilated fibers described in this paper which contain identical granules. Some may also arise from the small dense granules occasionally seen in Herring bodies.

Bohatirchuk, F.

doi: 10.1002/aja.1001170208pmid: 4160662

The combined technique of histology and radiography — stain historadiography (Bohatirchuk, '57a) — was used for studies of cartilage calcification. The main advantages of the technique are: a. X‐ray specificity in the detection of calcium; b. the possibility of a morphological visualization of calcium in biological tissues at a microlevel. Three patterns of cartilage calcification were observed: 1. columnar; 2. expansive; 3. ubiquitous. Stain historadiographs suggest that the cartilage cell rather actively participates in the calcification: a. calcium deposits are often found within the cytoplasm and cell membrane; b. some cartilage cells are frequently entombed in intraosseous lacunae. The latter phenomenon is especially often observed in the ubiquitous type of calcification.