摘要:

AbstractThe relationship between vitamin A deficiency and estrogen as etiological agents of uterine stratified squamous metaplasia (keratinizing metaplasia) was studied using the rat. This is the initial attempt to correlate plasma levels of vitamin A with the uterine lesions. From the results the following conclusions can be drawn. Uterine metaplastic lesions which develop in estrogen‐treated rats are not a result of generalized hypovitaminosis A, since plasma levels of vitamin A are not altered in animals treated with estrogen. Estrogen per se can cause uterine keratinizing metaplasia. The histopathologic lesions occur more frequently in vitamin Adeficient estrogenized rats having decreased plasma vitamin A levels as compared to rats with normal vitamin A intake. The two insults are complementary in producing epithelial metaplasia of the endometrium of the ra

ISSN:0003-276X    

DOI:10.1002/ar.1091520102

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

年代:1965

数据来源: WILEY

摘要:

AbstractA descriptive study of a 5.5 mm, Horizon XIV human embryo with myeloschisis was made. It is the smallest specimen ever recorded with this anomaly which is considered the embryonic forerunner of the common lumbo‐sacral meningomyelocele. The lesion extended from the twenty‐fifth existing somite caudally for 1 mm and was characterized by an everted neural plate, a loss of cellular polarity, asymmetry with a spread of neural tissue to the left and possibly a defective external limiting membrane of the neural tube. These findings indicate the lesion occurred before closure of the neural tube and are consistent with the observations of Patten ('53). They definitely do not support Gardner's ('60) hypothesis that rupture of a closed neural tube causes these lesi

ISSN:0003-276X    

DOI:10.1002/ar.1091520103

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

年代:1965

数据来源: WILEY

摘要:

AbstractGross and microscopic observations of graft and surrounding area were made after grafting during various stages of the hair growth cycle.All grafts were successful although temporary disturbance was observed when grafting was done during late anagen.Biopsies showed epidermal breakdown, even in telogen grafts, with repair being accomplished primarily by diversion of hair follicles to epidermal production. The later in anagen a graft was done, the less likely the follicles were to return to hair production later.Permanent loss of pigment was seen in some grafts, particularly those done in late anagen. Loss of pigment cells or their attachments from scraping the graft undersurface is a possible explanation, as is loss or damage to melanocytes while the follicles are producing epidermis.Delays and irregularities in hair growth cycles were also observed in host skin surrounding grafts. An explanation involving loss of inhibitor during grafting is proposed.The authors feel that hair growth activity in either donor or host is not an adequate explanation for graft rejection. It is also emphasized that hair growth is a poor criterion for graft survival.

ISSN:0003-276X    

DOI:10.1002/ar.1091520104

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

年代:1965

数据来源: WILEY

摘要:

AbstractFetal and neonatal endocrine pancreas of the golden hamster (Mesocricetus auratus) was evaluated cytochemically with regard to maturation of beta cell granulation (aldehyde fuchsin technique) and the structural findings were related to the release of insulin‐like activity (ILA)in vitro(rat epididymal fat pad bioassay).In the fetal pancreas 12 hours before birth, beta cells could not be distinguished histochemically although considerable ILA was released. In the absence of distinct islands of Langerhans at birth, a few cells showed AF+ granulation which was accompanied by a slight increase in the ILA. Maximal release of ILA occurred approximately on the second postnatal day when the AF+ granulation was denser and more abundant than at earlier periods. Beyond the second day, the rate ofin vitroILA secretion decreased although islets and beta cells showed progressive structural maturation. There was also a relative increase in the amount of exocrine tissue in the portions of pancreas used for bioassay. Advancing proteolytic inactivation may have accounted for the decrease in effective ILA when the latter was expressed per unit weight of tissue.The data indicate that in the golden hamster, beta cells are biochemically competent before they demonstrate cytochemical maturit

ISSN:0003-276X    

DOI:10.1002/ar.1091520105

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

年代:1965

数据来源: WILEY

摘要:

AbstractDetailed cytological studies of serial sections have been performed on 85 golden hamster embryos ranging between 9 and 16 days (4–27 mm) of embryonic development.Sequential cytological changes in the development of the thymus of the hamster into an active lymphocytopoietic organ indicate that lymphoblasts develop by the gradual proliferation and transformation of “undifferentiated” epithelial cells comprising the primordial thymus. The “undifferentiated” epithelial cells undergo two distinct lines of differentiation during early development of the thymus: into lymphoblasts and into stellate reticular‐epithelial cells which form the organ parenchyma. Transformation, both of lymphoblasts and reticular‐epithelial cells begins during the eleventh day of development prior to the separation of the thymus and parathyroid.That the lymphoblastic and lymphocytic elements appearing in the embryonic thymus of the hamster are of epithelial rather than mesenchymal derivation is indicated by the following: (1) the absence of lymphocytes, lymphoblasts and hemopoietic activity in the connective tissue surrounding the embryonic thymus before and during the period of initial lymphoblastic formation; (2) the presence of a continuous basement membrane surrounding the developing thymus; (3) absence of cells passing through the basement membrane during this phase of development; (4) the absence of vascularity or vascular invasion of the thymus until after the appearance of lymphoblasts in the thymic parenchyma; (5) the demonstration of a sequential series of morphological transitions between “undifferentiated” epithelial cells and lymphoblasts and (6) the subsequent homoplastic proliferation and maturation of the lymphocytic elements from lymphoblasts in the

ISSN:0003-276X    

DOI:10.1002/ar.1091520106

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

年代:1965

数据来源: WILEY

摘要:

AbstractFrom each of five litters of Sprague‐Dawley rats, littermates were sacrificed at 1, 3, 6, 12 and 24 weeks of age. The musculi extensor carpi radialis longus, soleus and plantaris were treated with glycerine while attached to the extremities and then dissected out and fixed in formalin. A transverse section through the thickest portion of the belly of each muscle was projected by a microprojector on graph paper. The entire section and the individual muscle fibers in representative areas within it were outlined. From this the total cross sectional area of the muscle; the number of fibers contained within it; the size, in terms of cross‐sectional area, of fibers; and the ratio of muscle to connective tissue were calculated.As the animals mature, there is an enlargement of the cross‐sectional area of the entire muscle and of the individual fibers. There is a definite increase in the number of muscle fibers during the first three weeks after birth which is the result of the differentiation into myofibers of myoblasts present in muscle fiber bundles at birth. A steady increment in the percentage of muscle to connective tissue throughout the entire growth period is pr

ISSN:0003-276X    

DOI:10.1002/ar.1091520107

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

年代:1965

数据来源: WILEY

摘要:

AbstractCritical examination of the fine structure of the outer segments of human rods shows that the membranes of at least some and probably most of the flattened saccules filling the outer segment are neither connected with the cell membrane nor with that of other saccules. The saccules typically possess a scalloped edge. The nine pairs of filaments in the ciliary connective become nine singlets in the base of the outer segment and lose their precise orientation before terminating somewhere in the length of the outer segment. The centriolar base in the inner segment possesses nine triplets of filaments and irregular numbers of club‐like, fibrous satellites. Rarely tubules insert in the satellite bodies and these may connect to the cell membran

ISSN:0003-276X    

DOI:10.1002/ar.1091520108

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe thyroid gland of normal specimens of the teleost, Seriola quinqueradiata, about 50–70 cm in length, obtained in April, were studied with the electron microscope. The apical surface of the follicular cell is irregular in outline and has fewer microvilli than that in higher vertebrates. The rough‐surfaced endoplasmic reticulum is well developed throughout the cytoplasm of the follicular cell, as in the higher vertebrates, and free ribosomes are widely distributed in the matrix of the cytoplasm.In all the follicular cells, there are several less dense or moderately dense droplets which are considered to be derived from Golgi elements. In some droplets occur aggregates of numerous wavy, fine filaments and crystal consisting of groups of thick needle‐like fibrils. Each fibril is 110–120 Å in diameter and composed of three layers comprising a less dense layer 35–40 Å thick, between two layers 35–40 Å in thickness. Dense granules such as those commonly found in the higher vertebrates were not observed in the thyroid cell of this fish, though a few round or oval bodies, which might be lysosomes, containing small vesicles, membranous structures, or wrapped whorled lamellae were noticed.The fine structure of the pericapillary region is similar to that of the higher vertebrates, though the endothelial pores ar

ISSN:0003-276X    

DOI:10.1002/ar.1091520109

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

年代:1965

数据来源: WILEY

摘要:

AbstractA study was made of the normal development of the lateral motor column (LMC) in the lumbo‐sacral region of the European grass frog,Rana temporaia.The results were then compared with the development of the LMC inRana pipiens(Beaudoin, '55), in order to determine if the difference in life cycle between the two species would result in differences in development of the column. The results show that the overall developmental pattern inR. temporariais no different from that found in other anura. There is a general decrease in the large number of cells present early in the larval period and a concomitant increase in the size of the remaining cells during development through metamorphosis. During metamorphosis, at least 80% of the original population of cells are lost. Immediately following forelimb emergence, nuclear area is at least 52% larger than the nuclear area of cells found at the earliest stage. In both species, the largest decrease in cell number and increase in cell size is at the time the circulating thyroid hormone concentration is at its highest level. Although the pattern of development in the two species is similar, the number and size of the LMC cells differ significantly between the two species during the late larval stages. This difference can be attributed to the difference in life cycle betweenR. pipiensandR. temporari

ISSN:0003-276X    

DOI:10.1002/ar.1091520110

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

年代:1965

数据来源: WILEY

摘要:

AbstractFetuses removed by Caesarean section (between days 17 and 21 of pregnancy) were compared with litter‐mates removed at autopsy (between days 21 and 23).In one diabetic group, all rats were treated with a large dose of insulin until Caesarean section when insulin treatment was stopped. No fetuses removed by Caesarean section showed glycogen infiltration when blood sugar was less than 240 mg/100 ml. At autopsy, glycogen appeared in all fetuses from mothers which had blood sugar levels above 240 mg/100 ml for two days or longer; no glycogen appeared in fetuses from mothers which had blood sugar levels below 240 mg/100 ml.In another diabetic group, all rats were treated with insulin, but the insulin dose was increased immediately after Caesarean section. All fetuses removed by Caesarean section showed glycogen infiltration when the blood sugar level was greater than 240 mg/100 ml. At autopsy, glycogen had disappeared in fetuses from mothers which had blood sugar levels less than 240 mg/100 ml for 2 to 3 days; glycogen persisted in fetuses from mothers which had blood sugar levels above 240 mg/100 ml.It is concluded that glycogen appears in fetal islets if blood sugar level is greater than 240 mg/100 ml for two days or longer. This change is both preventable and reversible and is influenced by the level of blood sugar and by the duration of hyperglycemi

ISSN:0003-276X    

DOI:10.1002/ar.1091520111

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

年代:1965

数据来源: WILEY