No abstract

Seventy-one cadaveric feet were dissected, with attention to communicating branches of the digital nerves, the diameters of the digital nerves, the distance between the metatarsal heads, and the presence or absence of interdigital neuromas. A communicating branch was absent in 52 feet (73.2%) and present in 19 specimens (26.8%). The communication was from the fourth to the third web space common digital nerve (i.e., from the lateral to the medial plantar nerve) in 11 specimens. A reverse communication, from the third to the fourth web space common digital nerve (i.e., from the medial to the lateral plantar nerve), was present in eight specimens. Neuromas were identified in the second web space in 26 specimens and in the third web space in 32 feet. The common digital nerve to the third web space was not thicker in feet with a contribution from the fourth to the third web space nerve. Additionally, the incidence of third web space neuroma in feet with this type of communication was not significantly greater than in those feet without an internervous communication. However, the intermetatarsal head distances and the ratios of the intermetatarsal head distance to the digital nerve diameter in web spaces 2 and 3 were significantly smaller in comparison to spaces 1 and 4 (P < .05). The morphometric data lend support to theories that explain the propensity for neuroma formation in both the second and third web spaces on a mechanical basis.(ABSTRACT TRUNCATED AT 250 WORDS)

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Four-week-old female mice were injected with estradiol, and the following day received intraperitoneally one p C / g m body weight of thymidinemethyL3H. At various intervals following the injection of thymidinezH, pairs of mice were sacrificed, the pubic symphyses excised and prepared for radioautographs of transverse sections. Examination of the radioautographs revealed that the highest percentage of labeled cells was to be found in the osteoprogenitor cell population at all time intervals examined. The number of osteoclasts and the percentage of labeled osteoclasts rose progressively. The percentage of labeled osteoblasts rose and then fell, but was at all times much less than that of the osteoprogenitor cell population.Since the osteoprogenitor cell population was the only one in which the percentage of labeled cells was high enough to account for the rise in the percentage of labeled osteoclasts, the conclusion was drawn that the labeled osteoclasts arose from the labeled osteoprogenitor cells.In support of the above conclusion, and in keeping with the theory that the osteoprogenitor cell undergoes "differential" mitosis, one daughter cell going on to become an osteoclast or an osteoblast, and one daughter cell remaining in the osteoprogenitor cell population, the number of silver grains over the labeled osteoclast nuclei was observed to be roughly one-half that over the labeled osteoprogenitor cell nuclei.The changes noted in the pubic symphysis during pregnancy or following the administration of estrogen have been investigated extensively since Hisaw's ('25, '26, '29) demonstration that the ovary, and specifically the corpus luteum, was involved in symphyseal relaxation. Burrows ('35) demonstrated that estrogen alone was sufficient to produce symphyseal relaxation, i t was later shown by Steinetz et al. ('65) that the presence of growth hormone was essential to bring about changes in the pubic symphysis. Talmage ('47) showed that estrogen priming was required for relaxin to have an effect on the symphysis. Hall ('47) noted that osteoclasts increased in number in association with the resorption of the pubic bones following the administration of estrogen. Further studies have been directed toward the estrogenrelaxin relationship, and the ligamentous changes that occur after hormone adminis-ANAT. REC., 171: 509-516.tration. Only occasional mention has been made of the osteoclast population, notably by Crelin ('69), who concluded that osteocytes, released during resorption and dedifferentiated to osteoprogenitor cells, are the source of osteoclasts. No work has been done to determine whether osteoprogenitor cells are the primitive precursor for osteoclastogenesis in the pubic symphysis, as has been done in the long bones.In contrast, a substantial amount of research has been directed toward determining the mode of action of parathyroid hormone (PTH) and the cell of origin of osteoclasts in normal and in PTH-stimulated bone. The currently accepted theory