ISSN:0003-276X    

DOI:10.1002/ar.1091860102

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

年代:1976

数据来源: WILEY

摘要:

AbstractThis study covers the period from the fortieth day after ovulation to the thirty‐eighth day after birth. In addition, lungs of two mature monkeys have been analyzed. Birth occurs about the one hundred sixty‐eighth day (24 weeks after ovulation). By the fortieth day the patterns of the bronchopulmonary segments are well established. These are the tools of the investigator. The curve of growth for the first 60 days parallels that of the rhesus monkey but is steeper than the human curve. At 63 days (9 weeks) pairs of rosette‐like clusters of epithelial buds (future alveolar ducts) have appeared on peripheral branches of the segmental bronchi and continue to grow in size until the twelfth week. Then they resemble the paired rosettes of human acini of the seventeenth postovulatory week (Boyden, ′74) and probably represent the primitive unit from which the human was derived. In both man and monkey, canalization of the rosettes starts at about the samerelativetime (the 17th and 12th week, respectively) and spreads centralwards from the rosettes along the bronchioles of each segmental bronchus. In man, canalization formsacini(alveolar ducts and respiratory bronchioles). In the monkey, due to the monopodial pattern of branching, it producesracemesof alveolar ducts, each raceme ending basally in a pseudorespiratory bronchiole (127th day). By the one hundred fortieth day, enough surfactant has been secreted to support a premature infant. At one hundred fifty days, 11 generations of bronchi, followed by 16 of pseudorespiratory bronchioles, are present in the medial basal segment, followed in turn by 19 generations of prealveolar ducts (the latter provided with delicate spiral muscles) each giving off alternate branches of alveolar ducts. After one hundred fifty days of gestation, generations of bronchi, pseudorespiratory bronchioles, prealveolar ducts and cartilages (15) remain virtually constant for at least 38 days after birth. By the adult stage the number of generations of pseudorespiratory bronchioles has been reduced to three and the prealveolar ducts increased (at the former's expense) to 27. This study is concluded with a comparison of the lungs of the newborn monkey with those of the human/neonate an

ISSN:0003-276X    

DOI:10.1002/ar.1091860103

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

年代:1976

数据来源: WILEY

摘要:

AbstractQuantitative microscopic techniques were employed to determine relative mitotic activity of lobulo‐alveolar tissue in thick sections obtained from the inguinal mammary glands of colchicine‐treated post‐pubertal Lewis/Mai rats sacrificed at different phases of the estrous cycle. It was found that the magnitude of lobulo‐alveolar cell mitotic activity and the proportion of the lobulo‐alveolar tissue with mitotic activity undergo significant fluctuations during the estrous cycle. The frequency distribution of mitotic activity in lobulo‐alveolar tissue was different and heterogenous at each phase of the estrous cycle. The frequency distribution of nuclei in lobulo‐alveolar tissue during the estrous cycle showed only minor variations and could not explain the variation in mitotic activity. Similarly, no morphological differences were observed in the mammary gland which could account for the variation observed in mitotic activity.It was concluded that the variation in mitotic activity of lobulo‐alveolar tissue is probably related to alterations in the generation time of lobulo‐alveolar cells imposed by cyclical variation in ovarian hormones during

ISSN:0003-276X    

DOI:10.1002/ar.1091860104

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe fine morphological and cytochemical (acid phosphatase) changes occurring during holocrine cell lysis in the sebaceous preputial gland of the adult rat were investigated. When cells reach full differentiation cisternae of the widespread rough endoplasmic reticulum show invaginations of the wall. Cytoplasmi areas comprising such altered cisternae, normal RER and some mitochondria, are later sequestered into autophagic vacuoles, either surrounded by a single membrane (type I‐bodies), or by a thick wall formed by concentric membranes (type II‐bodies). Other vacuoles with similarly stratified wall and containing debris and acid phosphatase appear in cells at the next stage of involution. These autophagic vacuoles (type III‐bodies) are probably derived from type II‐bodies, and become gradually transformed into residual bodies rich in myelin figures, while the cell membrane and the nuclear envelope rupture. These findings show that prior to cell disintegration most of the cell cytoplasm, with the exception of the lipid and proteinaceous secretion granules and some mitochondria, is focally degraded within autophagic

ISSN:0003-276X    

DOI:10.1002/ar.1091860105

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe pars intermedia of non‐obese pigmented rats of the Zucker strain is described using transmission electron microscopy. Secretory cells appear similar to those described elsewhere in albino rodent hypophyses. Cells which may be equivalent to ACTH cells of non‐pigmented mice and rats are observed near theborder of the pars distalis. Melanocytes are observed to surround lobules of the pars intermedia and to penetrate among secretory cells. In addition, large granules which appear to be melanin are present within some pars intermedia cells. Portions of some cells near melanin or melanin‐like granules exhibit expanded rough endoplasmic reticulum and Golgi zones containing dense granules. Observations are discussed in relation to origin of the melanin, and its possible significance near cells known to produce melanocyte‐stimulating hormon

ISSN:0003-276X    

DOI:10.1002/ar.1091860106

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe relationship between developing spermatids and Sertoli cell junctional specializations was studied with the electron microscope during spermiogenesis and at spermiation. At stage I of the seminiferous cycle, the newly formed spermatids are found in apposition to junctional specializations at the lateral surfaces of the Sertoli cell. Visualization of the junctional site of this early stage appears to be dependent on orientation and plane of section. As differentiation proceeds, the spermatids elongate and come to lie within deep recesses of the Sertoli cell. At this time the junctional specialization is limited to the acrosomal portion of the spermatid. During the maturation phase, the spermatids, while maintaining the same relationship to the junctional specialization, approach the lumen. When stage VIII of the cycle is reached, the stage in which spermiation occurs, the spermatids are at the luminal surface. The relationship of the spermatid head to the junctional specializations is quite variable during this stage. Some spermatids are observed still attached to the Sertoli cell at the junctional site, while others are found completely or partially surrounded by Sertoli cytoplasm, but with no evidence of the normally interposed junctional specialization. Yet, in other instances, the spermatids are observed in a position slightly removed from the junctional site. Also evident are profiles of junctional specializations at a free surface of the Sertoli cell, there being no attached spermatid. In some instances the junctional specializations appeared in apposition to a residual body. In the case of the free surface profiles, the junctional specialization at times lined an empty cleft or crypt‐like recess, giving the impression that the spermatid head had just been dislodged from the junctional contact site. The findings indicate that the spermatid is in contact with a junctional specialization from its initial appearance and remains so until spermiation is initiated. It is postulated that spermiation is initiated through a physiological change in the junctional specialization resulting in loss of adhesion and consequent release of the sperm head from its attachment site. A similar mechanism is proposed in relation to the inter‐Sertoli junctional complex to account for the means by which the spermatocytes cross this barrier to reach the adluminal compartment of the seminiferous epithel

ISSN:0003-276X    

DOI:10.1002/ar.1091860107

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

年代:1976

数据来源: WILEY

摘要:

AbstractUsing a combination of single isotope and double isotope autoradiography after injection of3H‐thymidine and of3H‐ +14C‐thymidine, respectively, the cell cycle of normal and injured lens epithelial cells in the mouse was determined. Progenitor cells in the peripheral region of normal lens epithelium were found to traverse the replicative cycle in the same amount of time as the injury‐stimulated cells in both peripheral and central (wound) regions. The individual phases were also the same length, except for a slight shortening of G2in the injured epithelium. The durations of the phases were: S: 11–12 hours; G2: 1.5–2 hours; M: 4.2–5 hours; G1(derived): 38–44 hours; and total cycle: 55–61 hours. Two findings were significant in view of previous observations that injury to mouse lens seldom induces lens opacity. First, while the cell cycle duration was not affected by injury, a burst of proliferation of potentially active cells ensued. And, secondly, this burst of proliferation involved only one cell cycle. Only a small number of cells, equivalent to the normal progenitor compartment, continued into a second replicative cycle. The wound was healed, therefore, mainly by one division cycle involving a larg

ISSN:0003-276X    

DOI:10.1002/ar.1091860108

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe contribution of progenitor cells in the normal peripheral region of mouse lens epithelium to healing of a centrally located wound was studied using an autoradiographic technique designed to follow migrating3H‐thymidine labeled cells. It was found that few progenitor cells labeled before or at the time of injury migrate toward the wound and hence contribute little to the repair of the wound. Moreover, the central injury did not delay or reverse the normal migration of the labeled peripheral cells in the opposite direction into the bow. It is concluded from this and other studies that a central injury to the mouse lens is healed mainly by numerous local cells which are stimulated for the most part to traverse one replicative cycle of normal duration, and that the injury does not affect formation of new lens fibers. These findings are thought to be related to the observed low incidence of traumatic cataract in the mous

ISSN:0003-276X    

DOI:10.1002/ar.1091860109

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

年代:1976

数据来源: WILEY

摘要:

AbstractEarlier work has suggested that terminal nerve fibers in the periphery of the dental pulp are linked to one another and to odontoblasts by gap junctions although positive identification of the junctions was lacking. In this study, the lanthanum hydroxide tracer technique has been used to demonstrate that the junctions in this area do have the characteristic features of gap junctions, a wide dark intermediate line in transverse section, stippling in oblique section and a globular arrangement of sub‐units in tangential section. Other studies have shown these junctions to be of low electrical resistance although the functional importance of this characteristic in this situation has not been determine

ISSN:0003-276X    

DOI:10.1002/ar.1091860110

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

年代:1976

数据来源: WILEY

摘要:

AbstractBesides the well‐known striated muscle fibers, the cremaster muscle of the guinea‐pig contains smooth muscle fibers, which appear either as isolated elements or as networks. These smooth muscle fibers are embedded within a matrix of the compact fibrous coat of collagenous connective tissue which covers the vaginal surface of the striated muscle layer. Presumably the smooth muscle fibers maintain the initial, fast contraction produced by the striated muscle fibers, thus attaining an economical, tonic elevation of the testi

ISSN:0003-276X    

DOI:10.1002/ar.1091860111

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

年代:1976

数据来源: WILEY