journal article
LitStream Collection
Home
McNulty, John A.; Nafpaktitis, Basil G.
doi: 10.1002/aja.1001500402pmid: 596340
The morphology of the pineal complex was compared in seven species of lanternfishes (family Myctophidae) using both light and electron microscopes. On the basis of compactness of the pineal end‐vesicle and presence or absence of a dorsal sac, the species in this study were divided into two groups. This grouping seems to correlate well with current views on the phylogenetic relationships among these fishes. Receptor cells and supportive cells are described in the pineals of all species examined. The deepest‐dwelling of the forms studied, Parvilux ingens, showed a significant increase in the mean number of lamellar membranes in the outer segments of the receptor cells and a higher convergence ratio of receptor cells to ganglion cells as compared to the shallow‐dwelling form Tarletonbeania crenularis. Accordingly it is suggested that the pineal of P. ingens is more photosensitive. Additional differences among species were found in the ultrastructure of the supportive cells. Dorsal sacs were absent in the three shallowest‐occurring myctophids studied. In those species with a dorsal sac, its close association with the pineal‐end‐vesicle suggests a functional relationship between the two structures.
doi: 10.1002/aja.1001500403pmid: 596341
Allometric growth in the innominate bone has been studied in eight primate taxa. A total of 266 skeletons were examined and the lengths of the ischial and pubic rami of the right innominate bone and the bicondylar length of the right femur were measured. These data were converted to natural logarithms and the allometric relationships were studied. The taxa could be divided into two groups on the basis of the allometric coefficients.
Biddulph, David M.; Wrenn, Robert W.
doi: 10.1002/aja.1001500404pmid: 202159
Isolated renal cortical tubules from male hamsters were prepared for studies in vitro in which the effects of parathyroid hormone (PTH) on cyclic nucleotide metabolism and efflux of intracellular calcium were investigated. Morphological studies were also conducted to evaluate the effects of the isolation procedure on the structural characteristics of the in‐vitro preparation of tubules. Tubules, consisting of proximal, distal and collecting duct segments, were observed by electron microscopy to retain specific cellular membrane specializations which characterize these segments in situ (microvilli; basal infoldings and junctional complexes). Organelles were generally normal in their appearance; however, some swelling of mitochondria and endoplasmic reticulum were occasionally observed. Enzyme activity, associated with either luminal membranes (alkaline phosphatase) or lysosome‐like organelles (acid phosphatase) was also retained following the isolation procedure. Preservation of the PTH‐dependent, adenylate cyclase system in isolated tubules was demonstrated, indicating that membrane receptors for PTH were intact. Effects of PTH on cyclic GMP concentrations as well as efflux of 45Ca were also demonstrated. These results indicate that the use of isolated renal tubules in vitro offers an excellent model system for further investigations concerned with mechanisms of hormonal action and regulation of cyclic nucleotide metabolism. The results also suggest a relationship in renal cortical tubules between PTH‐mediated production of cyclic AMP, metabolism of cyclic GMP and transport of calcium.
doi: 10.1002/aja.1001500405pmid: 596347
Growth sites within the newborn cartilaginous nasal septum have been identified by monitoring chondrocytic proliferation radioautographically. Tritiated thymidine was the labeling agent used. The results were tabulated and charted graphically; they showed the overall septum to be relatively active mitotically, yielding an average of 3.54 labeled cells per microscopic field counted. However, certain areas showed greater activity than others, namely the anterior tip (4.51 labeled cells/field), the midportion (3.98 labeled cells/field) and the posterior section of the presphenoidal tail (4.24 labeled cells/field).
doi: 10.1002/aja.1001500406pmid: 596342
This report describes the fine structure of guinea pig luteal cells during the period of maximum progesterone secretion and throughout involution, in ovaries that have been fixed by perfusion, a technique that provides optimal preservation of steroid‐secreting tissues. Smooth endoplasmic reticulum (smooth ER), a prominent organelle in these cells, is particularly well preserved by this method of fixation. During the time of maximal progesterone secretion, luteal cells contain abundant tubules and cisternae of smooth ER, many mitochondria, a well‐developed Golgi complex and some lipid droplets. This fine structural picture is consistent with active steroidogenesis.
doi: 10.1002/aja.1001500407pmid: 596343
The sacculi and lagenae from representatives of five species of catfishes were studied by light microscopy to provide an account of the anatomy of those structures and to determine whether phylogenetic changes can be detected in the inferior division of the membranous labyrinth among closely related ostariophysian fishes. The lagena showed little change among the forms used, while the saccule exhibited marked interspecies modifications. Anatomical variation was evident in the shape of the saccule, positioning of the interconnecting transverse canal, presence or absence of a release membrane, and, more notably, the position of the saccular macula and the shape and fluting pattern of the sagitta. Only minor variations were evident in the saccule and sagitta between the “primitive” conditions displayed in the siluroid form and those in the two bagroid representatives; in the latter forms, however, some positional modification of the posterior part of the macula from the “primitive” arrangement was present. In the bagroid representatives, the general morphology appeared to be stabilized early in the radiation, and individual changes suggest two lines of development within the group. The most significant modifications were evident in the loricaroid group where progression from the early representative to the more advanced form showed major changes in the inferior division of the labyrinth including loss of the anterior part of the saccule and sagitta, modification of the remaining part of the sagitta, and repositioning of the saccular macula. The pattern changes in the saccule generally agreed with the phylogenetic sequence proposed by Chardon (′68) for catfishes.
Lee, Sue Y.; Mossman, Harland W.; Mossman, Archie S.; Pino, Guido Del
doi: 10.1002/aja.1001500408pmid: 596344
The site of umbilical cord attachment in ruminants indicates the limited segment of the uterus where blastocyst attachment occurs and could have potential significance for locating presumptive nidation sites. Measurements of the site of cord attachment were made on impala (Aepyceros melampus) and common duiker (Sylvicapra grimmia) at several stages of gestation. Both implant only in the right uterine horn although they ovulate from either ovary. Relative to uterine length, cord attachment in impala is somewhat closer to the cervix than it is in common duiker. As pregnancy advances in common duiker, the relative position of cord attachment becomes closer to the tubal end. This relationship was not seen in impala and may perhaps be attributed to inadequate data. Upon extrapolation of the data from common duiker, a presumptive attachment area is suggested for this species. This region is located at about 41% of the distance from the internal cervical os to the uterotubal junction. Similar cord attachment data could be used in any ruminant species to indicate the existence and location of a specific nidation site.
doi: 10.1002/aja.1001500409pmid: 596345
Six adult cats received unilateral cochlear injections of 30–70 μCi 3H‐leucine (3‐H‐leu) in saline. After 20–48 hours, their brains were prepared for autoradiography. The octopus cell area (OCA) and the dorsal region (DCN) of the cochlear nucleus of both the injected and uninjected sides were studied in detail. Grain counts of autoradiographs always showed much greater label in the injected side. Autoradiography confirmed uniform distribution of primary afferents in the OCA, as seen in grain counts over the whole area (both somata and neuropil); however, grains were more densely packed over somata than neuropil of the OCA. In DCN, grain counts showed a gradient of label from the deep to superficial layers, a greater density of label over somata than neuropil of the deep DCN, and uniform distribution of label over the whole fusiform cell layer of the DCN. These results showed (1) best resolution and localization in cats that survived 24 hours and with exposures of two weeks, (2) no significant diffusion of label to other CNS regions than the auditory nuclei,and (3) transneuronal transport of label after 48‐hour survival times. Liquid scintillation counts (LSC) of cochlear nerve roots ipsilateral and contralateral to the injection showed at least a 10:1 ratio in all cats. This report not only gives new autoradiographic evidence of the distribution of primary afferents within the caudal cochlear nucleus, but also provides a useful approach to the study of distribution of specific amino acids implicated in central neurotransmission by cochlear terminals.
Silver, Alene F.; Fleischmann, Robert D.; Chase, Herman B.
doi: 10.1002/aja.1001500410pmid: 596346
Melanocyte‐precursor cells have been described previously in telogen and early anagen hair germs by observation of Epon sections using light microscopy. The existence of these precursor cells has not been generally accepted due to lack of ultrastructural evidence. It is our purpose to describe these cells using transmission electron microscopy. We studied hair germs of the dorsal skin of adult mice in the appropriate stages of the hair cycle prior to melanogenesis.
Showing 1 to 10 of 10 Articles