摘要:

AbstractParotid glands of adult pigs were studied by light and electron microscopy. The parenchyma consists of acini, intercalated ducts, striated ducts, and excretory ducts.Acini had little affinity for periodic acid‐Schiff and were alcian blue‐negative at pH 2.6 or 0.5. These results indicate a paucity of neutral mucins and an absence of sialo‐ and sulfomucins. Histologically, acinar cells had vacuoles which corresponded ultrastructurally to large electron‐lucent secretory granules. The latter contained electron‐dense bodies and lipid droplets. Acinar cells differed histochemically and ultrastructurally from typical serous cells and were classified as special serous.Intercalated duct cells near acini contained electron‐dense secretory granules and numerous microfilaments. Cells in distal segments lacked secretory granules.Striated ducts were lined by two types of columnar epithelial cells, light cells and dark cells. Light cells were characterized by numerous infoldings of the basal plasma membrane, mitochondria between the infoldings, and electron‐lucent vesicles in the apical cytoplasm. The mitochondria contained tubular cristae. Dark cells were characterized by an abundance of microfilaments and numerous infranuclear processes which extended to the basement membrane.Excretory ducts, in addition to light and dark cells, also contained basal cells and goblet cells. Mitochondria in the light cells had flattened rather than tubular cristae.The pig parotid is a unique salivary gland and the most atypical mammalian parotid gland studied thus far. Mitochondria with tubular cristae and vacuolated special serous cells with lipid in the secretory granules are hallmarks of th

ISSN:0002-9106    

DOI:10.1002/aja.1001520402

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

年代:1978

数据来源: WILEY

摘要:

AbstractThis study investigated the relationship between alterations in a basicranial line and changes in the upper respiratory system of selected non‐human primates and of man. This was done through multivariate analysis of craniometric measurements which describe midline exocranial flexion, and compares the analytical results with previous postmortem findings on upper respiratory structure and function.Craniometric analysis has shown that the skulls of the non‐human primate species studied and those of newborn human infants are relatively non‐flexed exocranially between the posterior border of the hard palate and foramen magnum. This finding corresponds to the relatively high position of their upper respiratory structures. In this group the tongue lies entirely within the oral cavity, and the epiglottis is found intranarial.After approximately the second year, humans exhibit marked exocranial flexion between the hard palate and foramen magnum. These basicranial changes coincide with concomitant changes occurring in the positional relationships of the upper respiratory system. After the second year the tongue and larynx have descended considerably into the neck, greatly altering their functional relationships.There thus appears to be a relationship between the exocranial orientation of the basicranium and the positioning of upper respiratory structures. There also appears to be a direct structural, and possible functional, relationship between (1) the position of the larynx, (2) the orientation of the pharyngeal constrictor muscles, and (3) the orientation of the basioc

ISSN:0002-9106    

DOI:10.1002/aja.1001520403

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

年代:1978

数据来源: WILEY

摘要:

AbstractExtensive investigation of the sensitivity of the descended testis to abdominal temperature, and of its thermo‐regulation by the scrotum, has so far failed to explain the adaptive significance of the scrotal state. The present viewpoint, derived primarily from comparative anatomical and from experimental studies, suggests a different line of reasoning – that descent into a scrotum has been influenced primarily by the need for migration of the cauda epididymidis to this cooler location; testicular descent is seen as a merely mechanistic event which enables the cauda epididymidis to project from the body, but has no significance for the biological function of the testis as such.The possibility that some advantage derived by the sperm‐storage region of the epididymis has been a prime determinant in the evolution of the scrotum is suggested by at least three anatomical features. This is indicated firstly by the relationship of testis and cauda epididymidis to each other in cryptorchid and in scrotal species. In natural cryptorchids (e.g., many insectivores and hystricomorph rodents) which express the transitional stage in testicular descent, the cauda generally precedes the testis within the cremasteric sac, thereby lying closest to the integument. In the scrotum, the disposition of the cauda epididymidis ensures that it occupies the coolest site there also. A second consideration concerns the curious course traced by the Wolffian duct in cryptorchid and scrotal mammals; for its diversionary route along and beyond the border of the testis would seem illogical and unnecessary were descent into a scrotum related solely to the function of the testis. This U‐shaped disposition of the duct, which retraces its course from the acute flexure of the cauda, is seen here as a device which permits the cauda epididymidis to occupy a cooler site, whether this be subintegumental or scrotal. Thirdly, although evidenced to different degrees and not in all species, a variety of scrotal features, e.g., a circumscribed hormonally‐determined baldness, exaggerated dartos responsitivity and, occasionally, black pigmentation of the peri‐caudal surface, as well as the presence of a fat pad between cauda and testis, each appear to favor controlled cooling of the caudal epididymidis. In no animal, by contrast, does the form of the scrotum and the disposition of its content seem designed for preferential cooling of the testis.These considerations do not explain the adaptive significance of the scrotum or the reasons for its variable occurrence among mammals. However, with a few exceptions found particularly amongst marine mammals, a scrotum characterizes polygynous species in which a dominant male achieves all or most of the fertile matings in a large group, and also those known to engage in multiple ejaculatory coitus with one female. Conversely, our limited knowledge of their habits notwithstanding, the frequency of sexual interaction for the males of most ascrotal species would appear to be relatively low. In light of its suggested relationship to the function of the cauda epididymidis, the possibility is raised that the scrotal state may be linked to the sexual capacity of the male, in particular the ability to produce fertile ejaculates repeatedly within a limited per

ISSN:0002-9106    

DOI:10.1002/aja.1001520404

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe effects of body temperature on sperm maturation and sperm storage in the epididymis have been studied in rats and rabbits by surgical reflection of the epididymis into the abdomen without disturbing its continuity with a functional scrotal testis. Rats so treated remained fertile during a period of 13 months, as judged by a sequence of normal litters born to their female cage mates, and cryptepididymal rabbits remained fertile for four months or more according to the individual, as evidenced by eggs fertilized and litters born after artificial insemination or natural mating. By contrast, spermatozoa confined by ligatures within an abdominal cauda epididymidis never retain their potential for motility for more than a brief period (5 days in rat; 8–10 days in rabbit), as compared with several weeks in contra‐lateral scrotal controls. It is uncertain whether their early death at abdominal temperatures resulted primarily from a suppressive effect of the temperature on the spermatozoa themselves, or on the caudal epithelium.Because of an increasing presence of apparently immature spermatozoa in the ejaculate of the first cryptepididymal rabbit between 7 and 11 months postoperatively, the rate of sperm transport through the epididymis of seven cryptepididymal rabbits was estimated by labelling with tritiated thymidine. As judged by the time of appearance of labelled spermatozoa in the ejaculate, transposition of the rabbit epididymis to the abdomen ultimately causes a progressive increase in the rate of sperm transport through it from a normal of nine days to two to five days in the cryptepididymal state.Thus, although maturation may eventually be compromised to some degree because of an increased rate of sperm passage, and sperm storage is inhibited, abdominal temperature apparently does not alter the essential biochemical nature of the epididymal milieu required for maturation. These results are reviewed in light of the suggestion (Bedford, '78) that the cauda epididymidis has been the prime mover in scrotal evolut

ISSN:0002-9106    

DOI:10.1002/aja.1001520405

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe retinal pigmented epithelium of the fetal guinea pig was examined for evidence of phagocytosis and degradation of outer segments. Beginning at the early stages of outer segment formation and continuing through the remaining fetal period, pigment epithelial cells contained large and small phagosomes with multi‐lamellated internal structure. Thus, mammalian retinal photoreceptor cells which normally develop and mature in utero in the absence of light undergo a process of phagocytosis of outer segment fragments comparable to that found in species whose retinae mature postnatally outside of the uteru

ISSN:0002-9106    

DOI:10.1002/aja.1001520406

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

年代:1978

数据来源: WILEY

摘要:

AbstractAccording to the staining intensities for AChE, the motor end‐plates of the rat diaphragm can be classified into strong (S) and pale (P) types. About 34% of the total end‐plates of the rat diaphragm are of S type and 50% of P type. The P end‐plates differ from S end‐plates in two aspects. First, the secondary subneural clefts of the S end‐plates are well developed. They are numerous, long, closely packed and often branched. On the other hand, the secondary subneural clefts of the P end‐plates are short, sparse and usually unbranched. Secondly, there seems to be a variation in AChE activity in the P end‐plates. Focal negative AChE areas are found in the subneural apparatus of some P end‐plates. It is concluded that the less well developed secondary subneural clefts and focal areas of negative AChE activity contribute to the paler staining of t

ISSN:0002-9106    

DOI:10.1002/aja.1001520407

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

年代:1978

数据来源: WILEY

摘要:

AbstractVarious growth parameters of the rat extensor digitorum longus muscle were studied during the first week of neonatal growth, including changes in weight, length, girth and fiber number. These quantitative studies were supplemented by ultrastructural analysis of fiber diameter and morphology in an attempt to determine the source of “new” muscle fibers in the neonate. In the 2‐day‐old extensor digitorum longus many of the myofibers were enclosed with other filamented cells (a satellite myofiber and/or myotube) in a common basement membrane, forming a cluster. Clusters accounted for 40% of the total independent filamented cells and clusters in 2‐day‐old muscles, for 2% in the 5‐day‐old, and for less than 1% in the 8‐day‐old. The decrease in the percentage of clusters occurred concomitantly with an increase in the number ofindependentfilamented cells. In the 2‐day‐old there were 2,932 ± 130 independent cells and clusters; this number increased by 90% in the 8‐day‐old muscle. Mean diameters of filamented cells (whether found independently or as part of a cluster) increased from 6.5 μm to 7.4 μm and to 9.5 μm on days 2, 5, and 8 respectively. Increased filamented cell diameter between days 2 and 5 was a result of growth of the smallest filamented cells into the medium‐size compartment. Between the fifth and eighth day postpartum, the increase was due to the growth of both small and medium‐size filamented cells. The largest fibers did not increase in diameter during the first week of postnatal development, maximal fiber diameter in the 2‐day‐old being 15.9 μm and in the 8‐day‐old, 16.1 μm. At two‐days the area through the widest girth of the muscle occupied by filamented cells was 35% of the total cross‐sectional area of the extensor digitorum longus. At eight days muscle fibers occupied 59% of the cross‐sectional area. To accommodate the myofibers the muscle belly increased its girth, and there was a decrease in the percentage of the area occupie

ISSN:0002-9106    

DOI:10.1002/aja.1001520408

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the hamster efferent ducts and epididymis was studied and the results were correlated with previously published data on the composition of luminal fluid obtained by micropuncture. Samples of the efferent ducts and parts of the epididymis designated initial segment, caput, corpus, proximal cauda, distal cauda, and “epididymal vas” were prepared. The efferent ducts contained principal cells characterized by a profusion of apical vesicles and numerous very large vacuoles that were distributed throughout the cytoplasm. Ciliated cells had few vesicles and vacuoles. Occasional cells contained many particles resembling glycogen. In the epididymis, the following trends were observed. The height of the epithelium and the size of the principal cells declined from initial segment to distal cauda. Apical vesicles and vacuoles with a light content were extremely numerous in principal cells of the initial segment and decreased progressively in the more distal regions. In the initial segment, basal and perinuclear rough endoplasmic reticulum was abundant and was distended with a material that resembled newly synthesized protein. Further distally in the epididymis cisternae of the rough endoplasmic reticulum were narrow and contained little intracisternal material. Light cells containing many vesicles, vacuoles, and lysosome‐like structures were very prominent in the caudal segments. The epithelium of the epididymal vas had features intermediate between cauda epididymidis and ductus deferens. The cytoplasmic droplet in luminal sperm began to migrate caudally between the caput and corpus epididymidis and reached the posterior extremity of the middle piece in the distal cauda. Some degenerating sperm were observed in the lumen of the distal segments of the epididymis.The abundance of cytoplasmic vesicles and vacuoles in principal cells of the efferent ducts and initial segment of the epididymis correlated with the site of greatest fluid absorption as determined by micropuncture studies, suggesting that these structures are involved in absorption of fluid from the lumen. Between the caput and distal cauda epididymal segments, where absorption of sodium and potassium but not of fluid occurred, there were few vesicles and vacuoles in principal cells, but the “light” cells were large and numerous and contained many vacuoles. The principal cells of the initial segment were best equipped with rough endoplasmic reticulum to synthesize

ISSN:0002-9106    

DOI:10.1002/aja.1001520409

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe avian anterior latissimus dorsi (ALD) is unique amongst vertebrates since it has been considered to be a true slow (or tonic) skeletal muscle. While the structure and function of the extrafusal fibers in the ALD have been intensively investigated, the intrafusal fibers of its muscle spindles and their relationship to the surrounding extrafusal fibers in this muscle have been virtually neglected. Serial frozen sections of this muscle from normal adult domestic chickens were tested for two separate enzymes: myosin ATPase after preincubations at differing pH (Brooke and Kaiser, '69) and NADH‐tetrazolium reductase, a mitochondrial‐bound oxidative enzyme. Both enzyme reactions were able to detect two distinct categories of extrafusal fibers in this muscle, as well as two classes of intrafusal fibers in its muscle spindles.Neither of the extrafusal fiber‐types reacted like typical fast (or twitch) fibers for myosin ATPase; they did not show a characteristic reversal in their relative staining patterns throughout the alkaline (pH 9.4) to acid (pH 4.6 and 4.3) preincubation range. The majority of fibers (type 1) were significantly larger in their cross‐sectional size, consistently stained lightly for ATPase, and showed high NADH‐TR activity. They represented about 84% of the total fiber population (n = 3540 ± 75). The other set of extrafusal fibers (type 2) constituted the remaining 16% of the total fiber population. They were smaller in diameter, exhibited high myosin ATPase activity, and reacted less intensely for the oxidative enzyme.The histochemical characteristics of the two kinds of intrafusal fibers were profoundly different from those observed in the extrafusal fibers. Their crosssectional fiber diameters were not significantly different from each other, and they exhibited a reversal in their staining reactions for myosin ATPase following acid preincubation for this enzyme.The results of this study concur with recently published reports of extrafusal fiber heterogeneity in the slow ALD muscle of the chicken. In addition, this work clearly demonstrates a histochemical dichotomy amongst the intrafusal fibers of muscle spindles in t

ISSN:0002-9106    

DOI:10.1002/aja.1001520410

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

年代:1978

数据来源: WILEY

摘要:

AbstractA non‐random spatial distribution of mitoses in proliferating rat endometrium was found by means of a quantitative microscopic technique. Nulliparous Lewis/Mai rats, 60–90 days of age, were given an intraperitoneal injection of colchicine (1 mg/kg) five hours prior to death, to arrest mitosis at metaphase. The middle one‐third of the right uterine horn was removed and fixed in Bouin's fixative for 24 hours. Several 5‐μm microtome sections were cut from dehydrated, paraffin‐embedded uterine tissue from each rat and stained with hematoxylin and eosin. Microtome sections of uterine horn which showed high endometrial mitotic activity, i.e., those obtained from rats killed in the metestrus phase of the estrous cycle, were selected for microscopic analysis. Using a binocular microscope equipped with an eye‐piece graticle, maps of uterine horn cross‐sections (3 non‐adjacent microtome sections/rat) showing the spatial distribution of mitoses along the surface of the uterine lumen were prepared. Data collected from the mitotic maps were: (a) the frequency of graticle squares containing mitoses and bounded on either side by graticle squares without mitoses; (b) the frequency of sequences of two or more adjacent graticle squares with mitoses; and (c) the frequency distribution of mitotically‐inactive intervals (number of graticle squares) between graticle squares enclosing mitoses. The observed frequency distribution of adjacent graticle squares with mitoses and the observed frequency distribution of spacing intervals between graticle squares with mitoses were examined for non‐randomness by generating from these data the Poisson frequency distributions expected assuming a random distribution. Goodness of fit between observed and expected distributions was tested using Chi‐square analysis.These analyses revealed, in each case, a significant deviation from randomness. Our data support a non‐random spatial distribution of mitoses in uterine epithelium and indicate that mitotic activity in rat endometrium occurs in localized spatial regions separated by relatively long regions of mitotically inactive endometrium.Possible mechanisms of production of a non‐random tissue distributio

ISSN:0002-9106    

DOI:10.1002/aja.1001520411

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

年代:1978

数据来源: WILEY