摘要:

AbstractThe reason for the presence of the paranasal sinuses has been a controversial subject since the time of Galen, 130–201A.D.In a review of the literature, the diversity of the numerous functions ascribed to these air‐filled cavities was found to be astounding. Many functions were ascribed only on the basis of opinion rather than scientific investigation and recent studies have illustrated the fallacy of these opinions. To date, not one proposed function has been universally accepted to be the essential reason for their existence.This review of the literature deals mainly with those theories of anatomical and physiological significance of the paranasal sinuses having received the most consideration and many of which are currently considered tenable. These are, as follows: (1) impart resonance to the voice; (2) humidify and warm inspired air; (3) increase the area of the olfactory membrane; (4) absorb shock applied to the head for protection of sensory organs; (5) secrete mucus for keeping the nasal chambers moist; (6) thermally insulate the nervous centers; (7) aid facial growth and architecture; (8) exist as evolutionary remains and/or unwanted air spaces; and (9) lighten the bones of the skull for maintenance of proper balance of the h

ISSN:0002-9106    

DOI:10.1002/aja.1001240202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractStimulated by the needs of surgery, common variations in the sympathetic pathways to the heart have acquired a practical significance. The cervical and upper thoracic sympathetic trunk was dissected on 24 sides in human fetuses at term, and the cardiac rami together with their communications studied and illustrated. To enable us to classify the cervical rami according to their sites of origin, the cervical sympathetic trunk was subdivided midway between ganglia into portions called ganglionic divisions; these divisions keeping the names applied to the ganglia in the Nomina Anatomica.Intermediate ganglia were found on the visceral outflow of the sympathetic trunk and are referred to as “distalintermediate ganglia” to distinguish them from the intermediate ganglia that have been describedproximalto the sympathetic trunk.Thoracic cardiac rami were almost invariably present, the third and fourth thoracic ganglia most frequently providing substantial contributions. Some thoracic cardiac rami were traced as far as the left anterior descending coronary plexus.The question of bilateral symmetry was also examined. Whilst a variety of features are commonly present on both sides, the first dissection in a cervicothoracic sympathectomy is no reliable guide to the detailed anatomy of the second side. The sympathetic pathways to the heart are extremely variable in their topography, and the diversity of arrangements encountered accounts for the morphological contradictions in the literature. So numerous are the possible variations that the outcome of a sympathectomy is unpredictable. Where denervation is incomplete, collateral sprouting and regeneration of nerves could even lead to hyperstimulation via the sympathetic pathw

ISSN:0002-9106    

DOI:10.1002/aja.1001240203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractOvaries of fetal mice obtained during the twelfth to eighteenth day of gestation and from the first to third postnatal day have been studied by electron microscopy. The interrelationships of follicle cells to oögonia and to connective tissue cells have received special attention. On day 12, when the female gonad can first be distinguished, relatively few large oögonia are visible. These are loosely aggregated and are accompanied by only a few follicle cells.On days 13 and 14 loose groups of oögonia become better demonstrated, and now are always surrounded peripherally by follicle cells. Beginning on day 14 very thin cytoplasmic processes of the follicle cells are interposed between adjacent oögonia. Subsequently, by following this process the follicle cells are drawn into the groups of oögonia or oöcytes. Increasing numbers of connective tissue cells and capillaries are growing into the cortex from the medulla and hilar regions. By day 18 and postnatal day 1 this ingrowth has separated the groups of oöcytes and follicle cells further. By postnatal days 2 and 3 most oöcytes have become enclosed by a follicular epithelium of either flattened, cuboidal or columnar cells. Many stages of zona pellucida formation can be recognized. It is postulated that the manner of fetal and early postnatal differentiation of the ovary explains a number of follicular configurations which deviate from the normal. At no time have cords of cells been observed to originate from germinal epithelium. By contrast the underlying tunica albuginea is derived by ingrowth of cells from the

ISSN:0002-9106    

DOI:10.1002/aja.1001240204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractHuman nasal respiratory mucosa has a limited capacity for localization of stimuli and discrimination of sensory modalities. In order to obtain morphological data on its receptor organs, histochmeical and electron microscopical studies were undertaken in six individuals ranging in age from 18 to 39 years.It was found that the nasal respiratory mucosa was supplied by non‐myelinated nerves which approached the mucosa in fascicles containing up to 200 axons. These fascicles were devoid of perineurial sheaths. They ramified repeatedly producing only one type of receptor organ — a simple terminal arborization. The finest terminal fascicles of the plexus ended either in the cell free zone of the lamina propria or in the spaces between the epithelial cells next to the basement membrane. The axons in the fascicles and in the endings were only partly insulated from one another by Schwann cell folds. The axoplasm of the terminal and preterminal nerve fibers contained accumulations of fine vesicles, simple granules and clusters of mitochondria. All nerve fibers gave a positive acetyl‐ and a negative butyro‐cholinesterase reaction.The plexiform endings of the nasal respiratory mucosa are different from any receptor organ of the adult human skin. They are reminiscent of the transitory, yet functional plexiform endings of the fetal skin which are found prior to the formation of the definitive receptor

ISSN:0002-9106    

DOI:10.1002/aja.1001240205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractSmooth endoplasmic reticulum appears in interstitial cells and Sertoli cells of 22–24d testes of fetal guinea pigs before the beginning of morphological differentiation of the male reproductive tract at 29d (Price et al., '67), and before the appearance of demonstrable 3β‐hydroxysteroid dehydrogenase, an enzyme important in steroid biosynthesis, in the interstitial cells at 29d (Ortiz et al., '66). This enzyme has not yet been demonstrated in the Sertoli cells.The smooth reticulum of the interstitial cells increases in amount, filling the cells with tubules by 27d, and later forming some fenestrated cisternae which are occasionally seen in whorls. In Sertoli cells, the tubular reticulum shows signs of degeneration at 26d. After this time the cisternal endoplasmic reticulum in these cells increases in amount and by 45d is predominantly smooth‐surfaced. Yet it is never as prominent as the smooth reticulum of the interstitial cells.Scattered clusters of ribosomes or polyribosomes are seen on the surface of the tubular reticulum of these differentiating cells. These polyribosomes become more widely spaced as the smooth‐surfaced areas increase and may be associated with the production of smooth membranes.Smooth endoplasmic reticulum is known to play a role in the production of steroid hormones, and therefore the extensive development of smooth reticulum in fetal interstitial cells is consistent with experimental evidence that implicates these cells as the chief source of steroid hormones governing male reproductive tract differe

ISSN:0002-9106    

DOI:10.1002/aja.1001240206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractTwo groups of male albino rats of 26 days old, were kept at 5°C and 28°C respectively. Their growth was studied by weekly gross measurements and biweekly radiographic investigations for 16 weeks. Compared with the controls at 28°C, the rats kept at 5°C showed the following effects of cold in their growth: (1) Smaller measurements at all ages; (2) Slower growth rates in the first two to four weeks; (3) Relatively shorter tail and shorter feet but body weight was the same as the controls of the same body lengths irrespective of age; (4) Shorter but relatively thicker bones; (5) A disto‐proximal stunting gradient was observed in the tail and limb bones, showing more severe effect in the distal segments and decreasing effect in the proximal segments; (6) Retardation of skeletal maturational status in the naked appendages (tail and foot); (7) Decreased number (1.4) of ossified caudal vertebrae.The above phenomena were discussed as results of possible reduction of blood flow to the skeletal tissue on cold exp

ISSN:0002-9106    

DOI:10.1002/aja.1001240207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001240201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY