Anatomical Record最新文献

Background: Deer antlers are useful models for studying bone growth and biomineralization in mammals. To achieve a better understanding of the mechanisms underlying the formation of primary cranial appendages in deer, the present study relates the histogenesis of primary antlers to changes in enzymatic (phosphatase) activities in the different tissue zones of this organ.

Methods: The growing tips of the primary antlers (4.3 to 5 cm in length) were removed from five fallow bucks, aged about 10 months. Part of the material was processed for light microscopy. The other part was cryofixed, and the different histologically defined regions were analyzed for the activities of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as well as for the concentrations of inorganic and organic phosphate.

Results and conclusions: Histologically, the primary antler could in distoproximal direction be divided into eight different zones (dermis; perichondrium; zones of cartilage formation, hypertrophy, mineralization, and degeneration; primary spongiosa; secondary spongiosa). The histological results demonstrate that the elongation of the primary antler proceeded through a modified form of endochondral ossification, resembling that seen during formation of pedicles and secondary antlers. The concentrations of the extractable activities of ALP and TRAP progressively increased from the perichondrium to the zone of cartilage mineralization. Thus, highest activity of TRAP during primary antler formation occurred at an earlier stage of tissue differentiation than in somatic endochondral ossification, where the enzyme is a biochemical marker of osteoclastic activity during bone remodeling. The present results might reflect the presence of osteoclastic precursor cells in the zone of cartilage mineralization as an adaptation to the rapidity of antler growth. Our findings of the contents of extractable ALP, inorganic and organic phosphate in the different tissue zones of the developing primary antler are in good agreement with previous studies analyzing epiphyseal growth plates and point to the fact that ALP causes a rise in inorganic phosphate and the removal of inhibitors for mineralization, like pyrophosphate.

Background: The percentage of satellite cells rapidly decreases in aneurally regenerating soleus muscles of rat. Also denervation of intact muscles causes fiber loss and regeneration, but the fate of satellite cells is unknown; myonuclei have been suggested to undergo changes resembling those in apoptotic cells.

Methods: Rat soleus and extensor digitorum longus (EDL) muscles were denervated at birth or at age 5 weeks and investigated after periods of up to 38 weeks. At least 400 myonuclei in each muscle were assessed by electron microscopy, and satellite cell nuclei were counted. In situ nick translation and tailing were performed after 30 weeks denervation in order to demonstrate DNA breaks associated with apoptosis.

Results: Myotubes indicating regeneration were prominent in the adult denervated soleus and deep layers of EDL muscles after 7 weeks and in the superficial parts of EDL muscle after 16 weeks. The percentage of satellite cell nuclei slowly decreased to less than one fifth of normal after 20-30 weeks. Almost all satellite cells had vanished 10 weeks after neonatal denervation. Degenerating myonuclei in adult, but not in neonatally denervated muscles, remotely resembled apoptotic nuclei of lymphocytes, but no evidence of DNA breaks was found.

Conclusion: Denervation of rat skeletal muscles causes, in addition to fiber atrophy, loss of fibers with subsequent regeneration. Proliferation of satellite cells under aneural conditions may lead to exhaustion of the satellite cell pool. This process is more rapid in growing than in adult muscles. Myonuclei in denervated muscles do not show DNA breaks which can be demonstrated by in situ nick translation.

Background: The extensor apparatus of the thumb displays obvious structural variations in its proximo-distal expanse. Its associated tissue comes in close relation to the dorsal aponeurosis that have varying topographical relationships to the extensor apparatus of the thumb. This region is especially important as the location of pathological and repair processes.

Methods: In this anatomical study using a modified embedding technique a histological description of the fibrous architecture of the dorsal aponeurosis and the peritendinous connective tissue body of the thumb is presented.

Results: The dorsal connective tissue of the thumb forms different layers of collagen lamellae as a peritendinous system around the tendons of the long and short extensor tendons of the thumb. This peritendinous laminar system as the main part of the dorsal aponeurosis is connected with both the capsular and the retinacular ligaments of the thumb.

Conclusions: It will be shown that the structural variations of the dorsal aponeurosis and peritendinous connective tissue are an expression of different topographical zones of stress along the lines of a balanced musculofibrous stabilization of the interphalangeal joint of the thumb. The expansions in the peritendinous intercellular space act as defined gliding spaces or clefts of the extensor apparatus.

Background: The possibility that mossy fiber endings in the rat hippocampal formation may contain cholecystokinin (CCK) was reexamined.

Methods: For this, CCK-immunoreactivity was examined by light and electron microscopy using the avidin-biotin complex method.

Results: At the light level, the topographical distribution of perikarya and processes with CCK-like immunoreactivity (CCK-LI) was similar to that previously described by others. Ultrastructural analysis of the dentate gyrus and CA3 region of the hippocampus revealed that some mossy fiber terminals contained CCK-LI most often affiliated with large, dense-core vesicles (DCV). Quantitative analysis revealed that 4-8% of the mossy terminal profiles examined (n = 350) contained CCK-labeled DCVs, which corresponded to 0.03-0.2 labeled DCVs per 100 microns2 of neuropil.

Conclusions: The presence of CCK-LI within mossy fibers in the rat suggests that there is less species variability in peptide expression in this pathway than formerly believed.

Background: Adult cetacean males, like non-mammalian vertebrates and other testicond mammals, have intra-abdominal testes. There is no evidence of a processus vaginalis in them. Testicondia in cetaceans is considered secondary as they are judged, evolutionarily, the descendants of terrestrial mammals (ungulates) with testis descent. A possible argument in support of the latter contention would be that cetacean fetuses develop gubernacula which are the primordia of the processus vaginalis and other structures associated with testis descent in other placental mammals. The present study intended to analyse cetacean fetuses in this respect.

Methods: Serial sections of 25 fetuses (total body length between 39.5 and 160 mm) of 4 cetacean species (Delphinus delphis, Phocoena phocoena, Eschrichtius robustus, Physeter catodon) were examined with special attention to the presence or absence of structures homologous to the gubernaculum of other placental mammals (rats and humans).

Results: Gubernacular primordia were observed in fetuses from about the time of onset of sexual differentiation. Their shape and anatomical relationship with the surrounding structures were similar as those in mammals with testis descent. The gubernaculum in males developed into a large mass of dense connective tissue in the ventral-caudal abdominal region at the site of the insertion of the mesonephric inguinal ligament and associated to the tip of the internal abdominal oblique muscle. No (or only very little) development of a processus vaginalis was noticed.

Conclusions: The results demonstrate initial emergence of mammalian-like gubernacular primordia in cetacean fetuses without their further development to elaborate structures required for testis descent. The findings support the view that cetaceans are secondarily testicond. It is suggested that (1) absence of the pelvic girdle together with (2) the development of structures in and beyond the caudal abdominal region, particularly the caudal hypaxial musculature, precludes the outgrowth, into caudal direction, of hollow organs (such as the processus vaginalis) from the abdominal cavity.

Background: The m. supraspinatus stabilizes the shoulder joint to bear the body weight, and the m. infraspinatus assists in extension and flexion of the joint in sheep. Postural muscles have many SO myofibers, whereas locomotory muscles have numerous fast-twitch myofibers. In sheep the distribution of myofiber types within the two muscles, necessary for a better understanding of postural function, remains to be clarified.

Methods: Muscle samples were removed from the whole transverse sections of the dorsal, middle, and ventral compartments of the m. supraspinatus and m. infraspinatus of sheep. Myofibers were classified into FG, FOG, SO-1, and SO-2 myofibers by histochemical methods.

Results: The distribution of SO myofibers changed more greatly in the m. supraspinatus (15.0-99.1%) than in the m. infraspinatus (24.5-62.3%). SO myofibers were concentrated markedly in the caudal and deep regions near the spine and fossa of the scapula in the m. supraspinatus and distributed more in the medial part than in the lateral part in the m. infraspinatus. Such changes were caused by increases in percentage of SO-2 myofibers and not SO-1 myofibers. The craniolateral regions of the m. supraspinatus and the caudolateral regions of the m. infraspinatus had many fast-twitch (FOG plus FG) myofibers suited for rapid extension and flexion of the shoulder joint.

Conclusions: The m. supraspinatus has the compartmentalized, deep, and caudal regions occupied by SO myofibers, which seem to be specialized for maintenance of the joint extension. The medial region of the m. infraspinatus may assist in the joint stabilization.

Background: In the present study, principal cells of the intermediate zone of the epididymis, an area situated between the initial segment and proximal caput, were observed to present morphological features distinct from those of principal cells of other regions.

Methods: The epididymides of adult rats were fixed by perfusion with glutaraldehyde and embedded in Epon. Administration of fluid phase tracers was performed in the case of several animals. Localization of anti-SGP-2 and anti-immobilin antibodies in conjunction with light (LM) and electron (EM) microscope immunocytochemistry was also performed.

Results: In the LM and EM, the most distinctive feature of many principal cells of this zone was the presence of apically located vacuoles referred to as giant endosomes due to their large size and because they readily incorporated tracers introduced into the lumen of the epididymal duct and were acid phosphatase-negative. Giant endosomes, containing electron-dense granular patches, appeared to form by the progressive fusion of small, medium, and large endosomes. In the supranuclear region, multivesicular bodies (MVBs) and lysosomes were present. Although smaller in size than the giant endosomes, MVBs and lysosomes contained the electron-dense patches. It is suggested from morphological images that giant endosomes fragment into smaller units corresponding to MVBs which gradually transform into lysosomes. Experiments using anti-SGP-2 and anti-immobilin antibodies revealed gold particles over the Golgi apparatus and secretory vesicles (150-300 nm) of principal cells of this zone as well as the luminal contents indicative of secretion of these proteins. Interestingly, giant endosomes were also immunolabeled with both antibodies as were stereocilia, coated pits and vesicles, and endosomes of various sizes; lysosomes were minimally labeled. These results suggest that principal cells of the intermediate zone endocytose as well as secrete SGP-2 and immobilin. The internalized SGP-2 and immobilin may correspond to that secreted further upstream and that, possibly due to their short half-life and terminated function, are removed from the lumen of the duct. Principal cells of this zone secrete these proteins possibly to replenish that lost by endocytosis.

Conclusions: Principal cells of the intermediate zone contain giant endosomes. The presence of such large structures suggests that the early events in endocytosis is a slower process in principal cells of this zone as compared to other regions. The fact that these cells both secrete and endocytose SGP-2 and immobilin adds to the complexity of our understanding of how principal cells function along the length of the epididymis.

Background: When examining the left atrial appendage by transesophageal echocardiography, differences in size and shape of the left atrial appendage are to be observed. The study was carried out with the aim of investigating the morphology of the left atrial appendage and to find associations with pathologic cardiac findings.

Methods and results: In 220 cases (106 female, 114 male, mean age 72 +/- 13 years) a cast of the left atrial appendage was made after the post mortem examination by using synthetic resin. In 198 cases an ECG was available (sinus rhythm n = 143, atrial fibrillation n = 55). The casts were described in respect to course and ramifications of the principal axis. The casts were measured concerning orifice diameters, outline, and volume. Most frequently (42%) the course of the principal axis was angulated below 100 degrees. More than five ramifications of the principal axis were found in 56% of the casts. The volume ranged from 770-19,270 mm3 (mean 5,220 +/- 3,041). When comparing the clinical and autopsy-data of the patients with the morphology of the casts, associations could be found between the volume of the casts and atrial fibrillation (7,060 mm3 as compared to 4,645 mm3 in sinus rhythm, P < 0.01), left ventricular hypertrophy (5,740 mm3 as compared to 4,639 mm3 without hypertrophy, P < 0.01), myocardial scars (5,923 mm3 as compared to 4,891 mm3 without scars, P < 0.05), closed foramen ovale (5,515 mm3 as compared to 4,037 mm3 with patent foramen ovale, P < 0.01), and left atrial appendage thrombi (8,566 mm3 as compared to 5,027 mm3 without thrombi, P < 0.01).

Conclusion: Left atrial appendages are formations greatly varying in volume and shape. This variability should be considered when interpreting images of the left atrial appendage, and in particular when diagnosing thrombi.

Background: Fine structural study revealed the intercellular coupling between the pericyte and the endothelial cells via the gap junctions, in the capillaries of the basal forebrain of rat embryos.

Results: Gap junctions were constructed by the adluminal plasmalemma of pericyte and the abluminal plasmalemma of endothelial cells.

Conclusions: Gap junctions are membranous channels that directly join the cytoplasms of the pericyte and endothelial cell and imply some substantial role for the pericyte on the endothelial proliferation. It is postulated that the function of the pericyte in the prenatal mammals are assigned to the regulation of the development of cerebral microcirculation.

Background: Since it has been found that new chromatin structures make their appearance in the nucleus during the DNA-synthesizing or S phase of the cell cycle, the question arises as to how these structures are related to the nascent DNA.

Methods: DNA-containing structures were detected in sections of mouse duodenal crypt cells by the DNA-specific osmium-ammine procedure. In the same sections, the nascent or newly-replicated DNA was localized during stages I-IV of the cell cycle (corresponding to four successive parts of the S phase) by immunogold labeling of the DNA precursor bromodeoxyuridine (BrdU) in mice sacrificed 10 min after its injection. Moreover, the fate of the nascent DNA with time was traced up to 6 hr after the injection. (The nomenclature of the DNA-containing structures is that proposed by El-Alfy et al., 1995.)

Results: Ten minutes after BrdU injection, the gold particles indicative of nascent DNA are associated with discrete nucleofilaments scattered in the nucleoplasm, but not with the compacted nucleofilaments making up the heterochromatin or the new S phase structures named "aggregates." The gold-particle-associated discrete nucleofilaments are classified into three types: a) The "free" nucleofilaments have been given this name, since they appear to be independent of heterochromatin and aggregates; nearly all gold particles are over these at stage I; but the numbers of particles over them decreases from stage I to IV. b) The "aggregate-attached" nucleofilaments project from the surface of the aggregates; the number of particles over these is high at stages II and III but decreases at stage IV. c) The "heterochromatin-attached" nucleofilaments project from the surface of the heterochromatin; the number of particles over these increases from stage II to IV. By 1 hr after BrdU injection, gold particles can be over loose clumps of nucleofilaments at stages I and II, but are mostly over small aggregates at stage II, midsized aggregates and small heterochromatin-associated "bulges" at stage III and large aggregates and large bulges at stage IV. By 2-6 hr, virtually all particles are over aggregates and bulges, frequently deep within them.

Conclusions: The distribution of the gold particles at 10 min reveals that DNA is synthesized in discrete nucleofilaments that are "free" or "aggregate-attached" or "heterochromatin-attached." In contrast, by one and especially two hours, the gold particles are present over aggregates and bulges, indicating that, after discrete nucleofilaments acquire nascent DNA, they are displaced to become part of these structures. More precisely, the aggregates arise from the repeated addition of replicated portions of "free" nucleofilaments, while the bulges arise from the repeated addition of replicated portions, of "heterochromatin-attached" nucleofilaments. Aggregates and bulges are the two initial building stones fr