摘要:

Seven of the 20 former species of the Phreodrilidae have been examined. Information derived from a study of this material has necessitated a re‐assessment of the interpretations of some of the anatomical features formerly employed in the separation of genera. As a result, all of the known species are merged in the single genusPhreodriluswith seven subgenera, 17 species and two taxa recognizable only as unidentifiable phreodrilid

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1966.tb02906.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

The alimentary canal of the maldanid polychaetesClymenella torquata(Leidy), andEuclymene oerstedi(Claparède (=Caesicirrus neglectusArwidsson, 1911) resembles, in many ways, that of the arenicolids. It is divided into buccal mass, pharynx, oesophagus, stomach and intestine, the three latter regions showing further subdivision. The buccal mass and anterior pharynx together form an eversible proboscis. The pharynx, oesophagus, and greater part of the intestine are ciliated. Simple feeding experiments, and histochemical tests, suggest that the stomach is concerned with the digestion and absorption of proteins, fats and carbohydrates, that the anterior intestine is a digestive and major absorptive region, and that the posterior intestine is a storage region. Waste materials are stored mainly in the wall of the oesophagus. A certain amount of intracellular digestion is carried out in the intestine ofEuclymenebut not inClymenella.The difference is attributed to the richer, diatomaceous diet ofClymenella.British individuals of this species, being apparently selective feeders, differ not only fromEuclymenebut also from American ones, both of which ingest the substratum non‐selectively.The pharynx, oesophagus and rectum are surrounded by plexuses of blood capillaries, while the remaining regions are associated with a blood sinus system which varies in position and form in the different regions, lying deepest in the absorptive intestine. The gut muscle seems to be more concerned with moving the blood forward through the sinus system and into the anterior plexus than with moving the food backward. One region of the stomach musculature is especially concerned with this circulation. Rectal respiration probably occu

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1966.tb02907.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Certain anatomical features of the pectoral girdle can be demonstrated to be functionally significant in the locomotor employment of the forelimb in different primate forms. In an earlier study, nine such shoulder features, examined individually, revealed the presence, within the Anthropoidea, of a graded contrast between brachiators, semibrachiators (progressing sometimes quadrupedally, sometimes by arm swinging) and quadrupeds. Within the Prosimii, corresponding contrasts obtain between hangers (resembling brachiators and semibrachiators in the frequent subjection of the arm to tensile forces) and quadrupeds (wherein, during locomotion, the arm functions as a strut).The compounding by canonical analysis of these nine features into mathematical functions best separating the means obtained for individual genera, reveals more detailed correlations between anatomical structure and locomotor pattern.Thus the first function disposes the Anthropoidea in a spectrum from the extreme brachiatorHylobatesthrough the lesser brachiatorsPanandGorillato such obtrusive semibrachiators asAtelesandBrachyteles, thence through intermediate members of the semibrachiator group to forms such as the infrequently arm‐swingingPresbytis, thence to more agile, arboreal quadrupeds likePitheciaandCacajao, and finally through intermediate members of this last group (e.g.Macaca) to such wholly terrestrial forms asPapioandErythrocebus.The second function provides further information in that the genera are arranged in a sequence which extends from largely or wholly terrestrial forms at one extreme (e.g.Gorillafrom among brachiators, low canopy species ofPresbytisfrom among semibrachiators,PapioandErythrocebusfrom among quadrupeds), to almost exclusively arboreal forms at the other extreme (e.g.Pongoamong the brachiators,BrachytelesandRhinopithecusamong semibrachiators,PitheciaandCacajaoamong quadrupeds).For the Prosimii, neither of these functions yields information additional to their separation into hangers and quadrupeds (coincident respectively with the semibrachiators and quadrupeds of the Anthropoidea) established by study of individual dimensions.All the subhuman primate genera lie close to the plane of the diagram formed by a combination of functions one and two, i.e. the third (and subsequent) functions are ineffective in their further separation. But, by the third function, man, whose individual dimensions agree sometimes with one group, sometimes with another, is clearly distinguished from all other primate forms—a distinction correlating with the unique functional activity of the human shoulder.Although this analysis separates various primate taxonomic groups below familial level, the particular locomotor features themselves do not (either singly or in combination) differentiate between Prosimii and Anthropoidea, nor between prosimian infraorders, or superfamilies of the Anthropoidea.However, other features of the shoulder girdle may make such a differentiation, and if so, a fossil form, studied in relation thereto and in relation to the analysis of locomotor features set out in this present study, could be interpreted both taxonomically and in terms of probable shoulder activ

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1966.tb02908.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

During late foetal life and at birth the gonads of both Grey and Common seals are enlarged, and there are indications of stimulation in the rest of the reproductive tract. The enlargement of the gonads is due mainly to the presence of very large numbers of cells resembling interstitial cells. The presence of groups of small round cells resembling lymphocytes and of cells intermediate between them and fully developed interstitial cells suggests that the small round cells may be the precursors of the latter. Whether these cells are lymphocytes or primitive mesenchymal cells cannot be stated with certainty. The ovaries of foetal Common and Grey seals contain no follicles beyond the stage where oocytes are ensheathed in a single layer of epithelial cells, but more marked follicular development was present in the ovaries of a still‐born Californian sea lion. No evidence of spermatogenesis was seen in the testes of any foetal or neonatal male seal. Regression occurs rapidly after birth and is nearly complete at the age of two weeks. The interstitial cells disappear by a process similar to fatty degeneration. Retrogression is accompanied by a remarkable obliteration of many blood vessels supplying the outer part of the medulla and the cortex of the ovary. The stimulus responsible for the precocious enlargement of the foetal gonads is removed with the birth of the young. The rapid decrease of endocrine influence after birth suggests that the placenta may be implicated.In the adult Common and Grey seal the corpus luteum persists until the end of pregnancy and begins to degenerate a few days after parturition. Follicular development occurs in the maternal ovaries towards the end of pregnancy and in the immediate post‐parturient period. The maternal ovaries are probably a source of oestrogens, both before, during, and after parturition, and such oestrogens could cross the placenta and affect foetal tissues.The prostate of all male foetuses of both species towards the end of pregnancy and immediately after birth is markedly enlarged. There is proliferation and hypertrophy of the prostatic alveoli, dilation of the tubules, and an increase in the size of the epithelial cells. A week after birth the weight of the gland is reduced by more than one‐half. Persistence and hyperplasia of the uterus masculinus occurs in some foetal and newborn pups of the Common seal, but no similar enlargement was seen in the Grey seal.The thyroid in the late foetal and neonatal Common and Grey seals showed wide differences in their histological appearances. The thyroid glands from an adult lactating seal of each species were widely different. In the Grey seal it was almost completely atropic but in the Common seal it appeared to be intensely active.The amount of medulla present in the adrenal of foetal seals is small by comparison with that of the cortex. A large number of cortical islands packed with lipid is present in the medulla, often containing more lipid than the cortex itself. The capsule of the adrenal varies considerably in thickness in different parts of the gland and in individuals of similar age. It is relatively thick in the glands of young animals and becomes much thinner in those of older individuals. In some specimens the capsule contains islands of cells containing transitional stages between capsular and glomerular cells. This supports the conception of a capsular origin of the cortical cells. The adrenal in seals is lobulated and folded, particularly in the adults. Large connective tissue trabeculae extend into the medulla from the capsule, accompanied by folds of the zona glomerulosa. The zona glomerulosa is very well‐developed and the large size of this zone may be associated with the seal's marine habitat. Pigment occurs in the cortex of a number of seal adrenals, more frequently in Grey than in Common seals, and appears to bear no relation to age or sex.The pituitaries from five Common seals were examined, and evidence was found that the neurosecretory material present in the hypothalamus and pituitary was considerably more conspicuous than in, for example, the dog. This may be correlated with the elaboration of posterior pituitary principle, and perhaps of antidiuretic hormone. It is possible that the capacity of the seal to secrete these principles is already well‐developed at birth and might be expected in the offspring of an aquatic mammal. In the adenohypophysis the maturity of the pars distalis at birth is striking, and the pars tuberalis and the pars intermedia are relatively large as compared, for example, with those of the dog. The α‐ and ß‐cells in the pars distalis of a newborn seal are comparatively mature. It is not, however, thought that the foetal and neonatal pituitary can alone be the cause of the gonadal hypertrophy, since the hypertrophy subsides rapidly after birth. It must therefore be concluded that the stimulus causing the hypertrophy before birth is derived primarily from an extra‐foetal source, but that a part may possibly be played by the foetal pituitary cannot be completely excluded. Anatomically, histologically, and behaviourally, the young seal is born in a remarkably mature state, probably more advanced comparatively than in most other mammals. It may thus well be that the endocrine system is so developed in the late foetal and neotal seal that it is particularly sensitive to the hormonal influences from the maternal side of the placenta, or originating in the placenta itself, or perhaps passing to the foetus

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1966.tb02909.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY