摘要:

AbstractA study of 40 racing Greyhounds and 60 mongrel dogs provided comparative data on the respective components of the canine electrocardiogram. Additional data revealed that the Greyhound had a heart weight — body weight ratio of 1.25 gm, a heart rate of 115 beats per minute, a systolic blood pressure of 254 mm of Hg, and a diastolic pressure of 139 mm of Hg. These findings in an athletic animal are compared with similar observations in untrained animals. The significance of this basic information is presented and discusse

ISSN:0003-276X    

DOI:10.1002/ar.1091490202

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

年代:1964

数据来源: WILEY

摘要:

AbstractAlthough melanoctyes appear to be limited to the hair folicles of adult belly skin of the PET mouse, they are found throughout the integument of the newborn. Trauma applied to the ventral belly skin of newborn PET mice results in the maintenance and augmentation of the melanocytes within the skin, even after the formation and growth of hair. The area immediately surrounding the site of trauma shows an increase in the number of melanocytes, apparently due in part to the disruption of the developing follicles and the consequent release of their pigment cells to the skin. UV irradiation also maintains a system of melanocytes within the ventral belly skin of PET mice.The significance of the maintenance and augmentation of melanocytes from the newborn into the adult by surgical trauma or UV radiation is discussed.

ISSN:0003-276X    

DOI:10.1002/ar.1091490203

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

年代:1964

数据来源: WILEY

摘要:

AbstractEmbryonic thymus provides a distinct advantage over the definitive thymus because the earliest formation of lymphocyte and lymphocytic precursors can be observed in a relatively simple and uncomplicated situation. Special cytological techniques combined with light, phase, and electron microscopy have been performed in this investigation involving over 150 chick embryos between 5 and 18 days of embryonic development.Sequential cytological changes in the development of the thymus into an active lymphocytopoietic organ indicate that lymphoblasts develop by the gradual proliferation and transformation of “undifferentiated” epithelial cells comprising the primordial thymus. Lymphoblastic transformation begins on the seventh day of embryonic development in the chick and is characterized by increased cytoplasmic and nucleolar basophilia and chromatin condensation. “Undifferentiated” epithelial cells undergo two distinct lines of differentiation between the seventh and tenth days: into lymphoblasts and into stellate reticular‐epithelial cells which constitute the organ parenchyma. All stages of lymphocytic maturation may be observed by 10–11 days as the thymus assumes a predominately lymphocytic character. Absence of lymphocytes or lymphocytic precursors in the connective tissue surrounding the embryonic thymus before and during the period of initial lymphoblastic transformation; presence of a continuous basement membrane surrounding the developing thymus; and absence of cells passing through this membrane during this phase of development indicate that the lymphocytic elements appearing in the embryonic thymus parenchyma are of epithelial rather than mesenchymal derivation. Although a contribution of mesenchymal elements to the lymphocytic population via vascular invasion and lobular formation in later stages of thymic development is unlikely, this question cannot be answered at this time. In spite of functional immunological distinctions between the lymphocytes of the chick thymus and bursa of Fabricius, the similarity of origin of the lymphocytic elements of these lympho‐epithelial organ

ISSN:0003-276X    

DOI:10.1002/ar.1091490204

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

年代:1964

数据来源: WILEY

摘要:

AbstractWhile studying the electrocardiograms of developing hearts it was noted that an adult type ECG could not be obtained in an embryonic heart which could not be blocked with digitalis. The need to know more about heart‐block was obvious. Intact embryos of 36 to 120 hours were floated on to glass plates and treated with digoxin‐Tyrode solution. Before 36 ± hours no dissociation of beat could be produced. The heart just stopped. At 40 ± hours a conal block followed by a midventricular block appeared. At 42 ± hours conal and midventricular blocks were followed by the first appearance of AV block. It was intermittent. At 47 ± hours conal block jumped to an incisive AV block. Midventricular block was rare. At 72 hours conal and then AV block occurred. Combinations such as four atrial to two ventricular to one conal beat could be readily produced while blood circulated.Electrocardiograms and cinephotomicrographs were taken of 72 and 96 hour hearts. Most striking was the fact that the typical Wenckebach phenomenon of adult heart‐block could be duplicated, i.e., an increase of PR interval preceding AV block followed by a shorter PR interval which again gradually increased preceding AV block. This sequence was repeated over and over. An explanation of these events i

ISSN:0003-276X    

DOI:10.1002/ar.1091490205

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe histology of the anterior hypophysis, thyroid and gonads of dwarf (dw) and Ames dwarf (df) mutants ofMus musculuswas compared. Orange G, aldehyde fuchsin and PAS stains were used to differentiate cells of the hypophysis. In both types of dwarf the anterior hypophysis was small, acidophils were lacking and the number of thyrotropic hormone producing cells was reduced. The thyroids were reduced in size, the follicles were small and some tissue was not organized into follicles. Testes were nearly normal. Ovaries were small and large follicles and corpora lutea were lacking.Growth hormone (STH) and thyrotropic hormone (TSH) were administered to both types of dwarfs. The treatment had no effect on the anterior hypophysis but number and size of follicles in the thyroid was increased The response was greater indfdwarfs; STH and TSH had more effect than STH alone. Testes of treated mice were only slightly changed but most of thedfand somedwmales became fertile. The ovaries became large and functional. Thyroids of dwarfs treated with thyroxine were not changed.It is concluded that the primary hormone deficiencies in both types of dwarf are the same, but that there are physiological differences as revealed by responses to STH and TSH treatment.

ISSN:0003-276X    

DOI:10.1002/ar.1091490206

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe medullae from the right adrenal glands of hamsters given one or three injections of reserpine were prepared for electron microscopy by fixation in buffered osmic acid while the contralateral left glands were fixed in formol‐dichromate for light microscopic determinations of the chromaffin reaction. The adreno‐medullary cells of these animals were compared with cells of untreated hamsters in order to determine if catecholamine loss was accompanied by changes in the electron opaque cytoplasmic granules.Ten and 15 hours following one reserpine injection (1 mg/kg) the chromaffin reaction was positive, whereas after 20 hours the reaction was negative, reflecting a catecholamine reduction. The negative chromaffin reaction was accompanied by alterations in granule ultrastructure. The dense central core of the granules was less electron opaque compared with those of control medullary cells. The decreased density likely reflected a catecholamine loss since the opaque appearance of the granules is attributed to the presence of the amines. Following three injections (1 mg/kg daily; three days) the chromaffin reaction was negative and most granules had disappeared from the cytoplasm. The results give evidence that, after limited reserpine injections (1 mg/kg; one injection), catecholamines can be released from the medullary cells without granule disappeara

ISSN:0003-276X    

DOI:10.1002/ar.1091490207

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe cytoplasm of the megakaryocyte in the rat spleen possesses three zones, the perinuclear, intermediate and marginal. The perinuclear zone is characterized by the presence of Golgi apparatus, ribosomes, endoplasmic reticulum, and mitochondria. These organelles are found also in the more voluminous intermediate zone which in addition exhibits platelet granules and an extensive development of vesicles from smooth‐surfaced endoplasmic reticulum to form demarcation membranes by coalescence. The marginal zone is almost devoid of the organelles and inclusions present elsewhere. Shedding of platelets appears to occur by extension of a paired demarcation membrane from the intermediate zone to the cell membrane and subsequent separation of its lamellae so that all of the essential organelles and inclusions of the intermediate zone may be included within the platelet. In addition, platelets contain vesicles which are probably pinocytotic in nature. Platelets are sometimes engulfed by the cytoplasm of phagocytic cell

ISSN:0003-276X    

DOI:10.1002/ar.1091490208

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

年代:1964

数据来源: WILEY

摘要:

AbstractThis study was undertaken to determine the relationship between Marshall's metalophilic reticular cells and the cells exhibiting non‐specific esterase and acid phosphatase activity in the rat spleen. Untreated and stimulated animals were used. Observations were made chiefly on the marginal metalophils of Snook. These cells showed strong acid phosphatase activity but only slight non‐specific esterase activity in untreated animals. Following stimulation non‐specific esterase activity increased in these cells. Within the nodules metalophilic reticular cells were always more numerous than cells with enzyme activity. Many of these metalophilic cells developed enzyme activity following stimulation. By the use of a restaining technique it was shown that all reticular cells possessing enzyme activity were also metalophilic but that the converse was not true. No mitotic activity was present in these cells.The results suggest that Marshall's metalophils are cells of the reticuloendothelial system in various stages of maturation and that, following stimulation, they may differentiate into mature phagocytic

ISSN:0003-276X    

DOI:10.1002/ar.1091490209

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

年代:1964

数据来源: WILEY

摘要:

AbstractThe tensor tympani muscle of the cat has been studied using histological and electrophysiological techniques. Histological studies revealed the presence of striated and smooth muscle fibers. The striated muscle fibers could be classified structurally as “Fibrillenstruktur” and “Felderstruktur” fibers, suggesting that both “fast” phasic and “slow” tonic fibers were present. Histochemical studies showed that some of the smaller (25–40 μ) Fibrillenstruktur fibers possessed relatively large end‐plate receptor areas which stained heavily for acetylcholinesterase. The membranes and cytoplasm of even smaller diameter fibers (9–25 μ) stained for acetylcholinesterase, similar to its distribution in muscle spindles of other muscles.Intracellular recordings showed that there were two distribution peaks of the resting membrane potentials — one at 40–50 mV, the other at 70–80 mV. When the nerve to the tensor tympani was stimulated by single square wave pulses, small junctional potentials (40 mV) followed by an after‐hyperpolarization, were recorded only from fibers with low resting membrane potentials — presumably slow Felderstruktur fibers. Large (70–90 mV) potentials which showed overshoot of zero potential, and which were preceded by initial long depolrizing potentials, were recorded from fibers with large resting membrane potentials. These fibers, which showed occasional spontaneous activity were presumably smooth muscle fibers. Potentials similar to those recorded from fast muscle fibers in other muscles were also occasionally recorded.It was concluded that the cat tensor tympani possessed slow and fast striated muscle fibers, smooth muscle fibers, and possibl

ISSN:0003-276X    

DOI:10.1002/ar.1091490210

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

年代:1964

数据来源: WILEY

摘要:

AbstractA cyanotic child and a newborn puppy were found to have a complicated cardiac malformation of essentially identical design. There was situs inversus of the cardiac chambers, hypoplasia of the anatomic left heart with transposition of the great vessels, pulmonary atresia, patent ductus arteriosus and drainage of all pulmonary veins into the anatomic right atrium. There was situs inversus totalis with pivotal levocardia in the child and dextrocardia in the puppy.The patient was markedly improved by a systemic‐pulmonary arterial anastomosis indicating the feasibility of palliative surgery in spite of the servere cardiac abnormality.The association of visceral heterotaxy with an identical complicated malformation of the heart in the human and canine species appears to indicate a common developmental deviation and thus is considered to be of teratologic significanc

ISSN:0003-276X    

DOI:10.1002/ar.1091490211

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

年代:1964

数据来源: WILEY