摘要:

AbstractThe weights of 75 human fetal thyroids were analyzed in relation to crown‐rump length, foot length, weight, and estimated gestation age. The ratio of thyroid weight to body weight was lower in the smaller fetuses and gradually increased until the fetus was 70–90 mm in crown‐rump length when the ratio attained a value close to that found in the newborn and adult. This period of development when the relative weight of the thyroid becomes constant coincides with the time of appearance of colloid and the onset of ability to concentrate iodine.A comparison of estimated age of fetuses in the Danish material and the formalin‐fixed fetuses from the Carnegie Collection shows the Danish fetuses under 40 mm in crown‐rump length to be four to six days older than the average given by Streeter. Streeter may have made his average too low and probably the relative ages of the two groups are c

ISSN:0003-276X    

DOI:10.1002/ar.1091480202

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

年代:1964

数据来源: WILEY

摘要:

AbstractCongenital malformations of the hamster eye, consisting of microphthalmia and anophthalmia have been noted consistently in the offspring of pregnant hamsters treated with intravenous injections of colchicine, Vinacaleukoblastine (VLB) and Vincristine (VCR) on the eighth day of gestation. In an attempt to compare the mitotic‐arresting activity of these three compounds on the lens and retina of the fetal hamster eye, various concentrations of the drugs were injected into pregnant hamsters on the fourteenth day of gestation and the fetuses recovered after three hours. Mitotic counts were done on comparable sections of lens and retinas of the fetuses. Colchicine has the most marked mitosis‐inhibiting activity of these three drugs. The most effective mitosis‐inhibiting dosage of colchicine also correlates with its most effective teratogenic dose. VLB and VCR do not inhibit mitosis in the fetal hamster eye as markedly as colchicine and their most effective mitosis‐inhibiting dosages are equal to or above levels which cause a 95–100% embryonic mortality. It is possible that some common biological mechanism other than inhibition of mitosis may be responsible for the similar teratogenic activity of these compounds. The natural resistance of the golden hamster to colchicine does not appear to be manifest in the developing embryo

ISSN:0003-276X    

DOI:10.1002/ar.1091480203

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

年代:1964

数据来源: WILEY

摘要:

AbstractBody weight and length, weights of 14 organs and 15 linear measurements are presented from 97Amblystoma tigrinum melanosticumbefore metamorphosis and 57 specimens after metamorphosis. These data are compared with similar measurements (previously published) on adult salamanders.Body weight and weights of the digestive tube and its subdivisions, liver, pancreas, spleen, eyeballs and brain are heavier in the larvae. The body weight decreases more than many of the organs and hence the percentage weights of the heart, lungs, liver, spleen, kidneys, gonads, eyeballs and brain are larger, relatively, in the post‐metamorphosis salamanders.Since body length is not significantly changed, the percentage lengths are much the same. Length of the digestive tube and its parts, jaw width and the width of the body at pectoral, belly and pelvic regions are all longer in the larvae. The limbs are the only percentage lengths greater in the post‐metamorphosis salamanders.All of the weights and all of the linear measurements are significantly correlated with body weight or length, respectively.Four organs show increases in percentage weights at all three periods: gonads, lungs, liver and spleen. Two others have an increase in post‐metamorphosis: heart and kidneys. The digestive tube and its parts and the pancreas have a relative decrease at the end of metamorphosis. The eyeballs are relatively largest in the post‐metamorphosis, and smallest in the

ISSN:0003-276X    

DOI:10.1002/ar.1091480204

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

年代:1964

数据来源: WILEY

摘要:

AbstractA marginal sinus, formed by the anastomosed terminations of white pulp capillaries, bounds the inner edge of the marginal zone. The endothelial lining on the nodular surface is complete. Pores appear along the lateral aspect thus allowing blood to pass freely into the interstices of the marginal zone. A dense aggregation of Marshall's metalophil cells occurs in the region of the marginal sinus. Such cells are lacking in the marginal zone.Intravenous injections of particulate matter were used to determine the course of blood flow and phagocytic potential. Ten minutes after injections, particles were found to be dispersed among the cells of the marginal zone. None were found in the marginal metalophils. In four hours the particles had cleared the marginal zone and were within red pulp macrophages. In a few rats, the marginal metalophils reacted positively to tests for iron. It is concluded that marginal metalophils represent a large reserve of potential phagocytes situated at a point where blood first leaves capillaries to enter tissue interstices.

ISSN:0003-276X    

DOI:10.1002/ar.1091480205

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

年代:1964

数据来源: WILEY

摘要:

AbstractIntimal proliferation in dog coronary arteries occurred in the vessel having the greatest range of motion. Within an involved segment of the artery, intimal proliferation could be related to the anatomy of the muscle bundles. Arterial muscle bundles originate from the adventitia, spiral around the artery and insert distally into the adventitia. The adventitia and the internal elastic lamina course along the long axis of the artery and are connected by elastin‐collagen fibers. Intimal thickening developed under the muscle insertion sites in regions where the adventitia was apparently placed under tension. In these regions, the net force of a muscle bundle contraction increases and shearing would occur between a muscle bundle at its insertion site and the remaining bundles gliding past it. This local shear force would then be transmitted to the internal elastic lamina through the elastin‐collagen fibers which connect it to the adventitia. Deformation and apparent injury of the internal elastica would follow and cause a fibrous tissue response. In the smaller arteries and arterioles, intimal proliferation occurred most prominently in the vessels supplying a mobile structure, i.e., anterior papillary muscle of the left ventri

ISSN:0003-276X    

DOI:10.1002/ar.1091480206

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

年代:1964

数据来源: WILEY

摘要:

AbstractA control group of guinea pigs ovulated 3.43 ± 0.41 ova or 1.72 ova per ovary. Unilateral ovariectomy (semispaying) on day 1 resulted in the ovulation of 3.71 ± 0.37 ova from the remaining ovary, whereas after semispaying on days 5 and 10, 2.80 ± 0.12 eggs were ovaluated. Unilateral ovariectomy during days 12, 14 and just prior to ovulation resulted in the same number of ova being ovulated from the remaining ovary as from the initial ovary removed. Semispaying at any day during the cycle did not alter cycle length.At day 1, all follicles from the previous cycle were atretic. At day 5 the current population of follicles were well developed with no atresia present. Ovaries removed on days 5, 10, and 12 had approximately the same distribution of large follicles with atresia appearing in all size ranges. At day 14, the number of large follicles was markedly decreased. However, after semispaying at day 5, the remaining ovary at day 14 had twice the number of Graafian follicles and twice the amount of atresia in these size ranges as the normal day 14 ovary.It is therefore likely that the compensatory response after unilateral ovariectomy in the guinea pig is due to an increase in the rate of proliferation of smaller sized follicles into larger ones. Day 12 seems to be the critical period of the guinea pig cycle. At this time, regression of the corpora lutea occurs, and perhaps of significance, the ability of the animal to compensate for unilateral ovariectomy is also lo

ISSN:0003-276X    

DOI:10.1002/ar.1091480207

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe luminal and glandular epithelia of the rat uterus during delayed implantation have been studied with the electron microscope. The tall columnar cells of the luminal epithelium are characterized by a distinct zonation of organelles. On the free surface there are short microvilli and occasional cytoplasmic extrusions, with terminal bars joining adjacent cells at their apical margins. Beneath the free surface are numerous pinocytotic vesicles and mitochondria. Above the nucleus are a prominent Golgi apparatus with large dilated vacuoles, and numerous dense inclusion bodies. Large clusters of lipid droplets and aggregations of mitochondria occupy the basal zone of the cell.The apical portion of the gland cell has fewer pinocytotic vesicles and the Golgi is smaller than in the luminal epithelial cells. Dense bodies are numerous above the nucleus. The basal portion of the gland cell is devoid of lipid, but there are often one or more enlarged mitochondria. Although a dense PAS+ substance fills the lumina of the glands, there is no obvious evidence of secretory activity in the glands during delay.The relationships of the epithelia to the environment of the blastocysts during delay is discussed.

ISSN:0003-276X    

DOI:10.1002/ar.1091480208

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

年代:1964

数据来源: WILEY

摘要:

AbstractThis report on the early human ilium is based on the Streeter collection, Carnegie Institution of Washington, Department of Embryology, Baltimore. The five phases in chondrogenesis, described by Streeter for the humerus ('49) and the horizons (Streeter, '42) are used in the description of the changes observed in the ilium. From horizon XV (7–8 mm, 30–32 days) to horizon XVIII (14–16 mm, 36–38 days) component cells of the ilium are mesoblasts. In horizon XIX (17–20 mm, 38–40 days) young cartilage cells have appeared. Both phase 1 and phase 2 cells appear in horizon XX (21–23 mm, 40–42 days), the former characterized mainly by the first appearance of intercellular material, the latter by their slender shape and arrangement in tiers. Phase 3 cartilage cells, cuboidal with many vacuoles, appear in horizon XXI (22–24 mm, 42–44 days). Increasing vacuolization of the cytoplasm of cells is noted throughout horizons XXII and XXIII until, in horizon XXIII (28–30 mm, 46–48 days) total disintegration of cells, a feature of phase 5, is evident. Thus the phases of cartilage differentiation described for the humerus are pr

ISSN:0003-276X    

DOI:10.1002/ar.1091480209

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

年代:1964

数据来源: WILEY

摘要:

AbstractUnilaterally ovariectomized and intact cattle were injected with 1,500 i.u. gonadotropins to induce superovulation, inseminated at estrus and autopsied 30 to 60 days post ovulation. The allantochorion was dissectedin situand the viability and position of embryosin uteromeasured. There was no difference between the intact and unilaterally ovariectomized animals in the number of corpora lutea. One to ten embryos were recovered per cow; intact animals had more embryos than the ovariectomized ones. One to two embryos migrated per uterine horn; the percentage of transuterine migration was lower in the intact animals than in the ovariectomized ones. In unilaterally ovariectomized and intact animals, a single uterine horn could sustain only one or two embryos. When the uterine horn contained one embryo, the embryo occupied the middle or upper two‐thirds of the horn. With the increase of the number of embryos the sites of embryos were unevenly spaced and overcrowded. This phenomenon led to a high rate of fetal mortality especially when the uterine horn contained more than two fetuses and transuterine migration failed to occur. The results are discussed in relation to endocrine mechanisms and species differences as they affect uterine contraction

ISSN:0003-276X    

DOI:10.1002/ar.1091480210

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

年代:1964

数据来源: WILEY

摘要:

AbstractIn seven human fetuses of C.R. lengths ranging from 38 mm to 100 mm primary ossification of the ilium has been described.In the 38 mm fetus the perichondrium at the caudal border of the ilium in the vicinity of the greater sciatic notch is intensely basophilic and contains osteoblasts. In another 38 mm fetus in the same area new bone is present.In the 50 mm fetus bone has spread cephalad over the internal and external surfaces of the ala of the ilium without invading the underlying cartilage.In the 58 mm fetus pores are present in the bone and through them osteoblasts and vascular elements are invading the disintegrated cartilage to form the primary marrow cavity.In the 66 mm fetus the primary marrow cavity has spread into the ala of the ilium.The whole process is similar to that seen in the primary ossification of the shaft of a typical long bone and follows the sequence described by Streeter ('49).

ISSN:0003-276X    

DOI:10.1002/ar.1091480211

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

年代:1964

数据来源: WILEY