摘要:

AbstractReciprocal interspecific F1hybrids of deermice (Peromyscus maniculatus) and oldfield mice (P. polionotus) differ significantly and substantially in fetal and placental, as well as adult, size and weight. Hybrid fetal mortality is associated with large conceptus size. Skin grafts were exchanged between and within the two species to ascertain whether any relationship exists between mean graft retention time and body size of fetuses and adults.P. maniculatusskin grafted toP. polionotusrejected significantly earlier than the reciprocal xenograft. All interspecific graft combinations rejected significantly earlier than intraspecific grafts. Pre‐immunization of femaleP. maniculatuswith con‐ and trans‐specific paternal spleen cell antigens reduced fetal, placental, neonatal, and ten‐day size compared with controls. Size, weight, fertility, and graft rejection data were compared with several theoretical models. The data were consistent with the hypothesis that immunological disparity between the species could produce marked size variations in reciprocal hybrids. Multiple minor histocompatibility factors can account for large placental size and fetal mortality inPeromyscushybrids. Physiological reproductive isolation may result from immunological differences between closely allied

ISSN:0022-104X    

DOI:10.1002/jez.1402240102

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe extensor muscle and chela of unoperated and transplanted regenerated limbs from two species ofUcawere examined to test the theory of neurotrophic control on crustacean muscle. Initially, tuberculation patterns, sensory hair number, and claw shape of the transplanted regenerated limb resembled those of the donor. Sarcomere lengths were donorlike except when the transplant was from male to female. Eventually the transplanted regenerated limb acquired some recipientlike features, although the claw shape and sarcomere length measurements of secondary regenerates resembled those of the donor. Because of these findings, it is no longer possible to hypothesize that innervation alone controls the growth and differentiation of muscle.

ISSN:0022-104X    

DOI:10.1002/jez.1402240103

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

年代:1982

数据来源: WILEY

摘要:

AbstractQuail–chick chimeras are created by transplanting pieces of quail tissue to chick. We have used antibodies combined with a cell surface marking technique [modified after Molday et al.('75)], to facilitate scanning electron microscopic (SEM) identification of quail cells in such chimeras. First, antibodies to quail RBCs were raised in rabbits by intravenous injection. Rabbit anti‐quail RBC serum was precipitated by ammonium sulfate, purified by DEAE chromatography, and cross‐absorbed with chicken RBCs. Second, sheep anti‐rabbit IgG was purchased commercially and further purified by affinity chromatography. Third, 900‐Å‐diameter latex beads were synthesized by aqueous emulsion copolymerization of methacrylates. Spheres were bound with diaminoheptane to create an extension arm which was further derivatized in a two‐step glutaraldehyde procedure. Purified sheep IgG was bound to the aldehyde‐activated spheres, with uncoupled sheep IgG removed by sucrose density centrifugation. To test the marker, rabbit anti‐quail IgG was added to 1% diluted quail RBCs. After washing, sheep anti‐rabbit IgG bound spheres were introduced. Washed cells were fixed in one‐half strength Karnovsky's and processed for SEM. Quail RBCs were uniformly decorated with beads, containing 2,000 beads per cell. Similarly treated chick RBCs show no binding to beads. Likewise, quail RBCs not pre‐treated with the rabbit IgG do not bind beads. Prefixed quail RBCs still bind latex‐conjugated beads, although at somewhat reduced levels. When mixtures of quail and chick RBCs were processed for identification: (1) sphere labeling was an “all or none” phenomenon; (2) the proportion of bead‐decorated cells observable in the SEM was the same as the proportion of quail RBCs provided in the initial mix; and (3) morphologically distinguishable embryonic chick RBCs did not label whereas under the same conditions, quail RBCs do. We further demonstrate that rabbit antibodies prepared by injection of stage 4 quail primitive streaks can be used to specifically label quail epiblast and mesoblast cells, providing markers for at least two germ layers. It is now possible to combine grafting techniques of known success,

ISSN:0022-104X    

DOI:10.1002/jez.1402240104

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

年代:1982

数据来源: WILEY

摘要:

AbstractElectrical parameters were simultaneously measured with unidirectional fluxes of Cl−and Na+through isolated short‐circuited skin of a marine teleost, the shanny (Blennius pholisL.). The mean transepithelial potential TEP developed across the skin was 10.6 ± 0.4 mV (n = 6) in open‐circuit conditions. When the skin was short circuited, the mean short circuit current Iscwas 35.1 ± 2.7 μamp·cm−2, which represented the difference between mean Cl−and Na+net fluxes (1.2 ± 0.2 μEq·hour−1·cm−2equivalent to 32.5 ± 5.4 μamp·cm−2). The junctional complexes between the different cells of the epidermis were also studied. Epithelial cells were linked to each other by tight junctions as well as epithelial and accessory cells. In contrast, junctions between chloride and accessory cells were characterized as shallow junctions. The Na+and Cl−transport through the skin of the shanny is discussed with reference to the implication of the junctiona

ISSN:0022-104X    

DOI:10.1002/jez.1402240105

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

年代:1982

数据来源: WILEY

摘要:

AbstractIntracellular recordings and Lucifer dye injections were used to locate five of the six tonic abdominal flexor motoneurons, as well as several of the extensor motoneurons in the fourth abdominal ganglion of the crayfish,Procambarus clarkii.Each motoneuron was identified by its morphology and root records, and each was characterized by its inputs from identified flexion and extension‐evoking interneurons (command fibers). Finally its connections to other motoneurons were examined by current injection experiments.As indicated by others, the somata of most of the tonic flexor motoneurons are electrically silent; recordings were, therefore, made from neuropilar branches, but at unknown locations.The majority of motoneurons were found to be polysynaptically connected to the command neurons, although several apparent monosynaptic excitatory and inhibitory connections were also seen. Coupling between motoneurons was confirmed, but the major functional input to the motoneurons was from premotor interneurons. Coupling between motoneurons and interneurons is also indicated by the data, and may be responsible for the inhibition of some motoneurons seen during depolarizing current injections into other motoneurons. Again, such coupling is shown to be a minor influence in the overall organization of the behavior.The data suggest that flexion and extension behavior is predominantly organized via interneurons including the command fibers rather than by connections among the motoneurons themselve

ISSN:0022-104X    

DOI:10.1002/jez.1402240106

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe eyes ofBullaexpress a circadian rhythm in optic nerve impulse frequency.Bullaalso exhibit a circadian rhythm in locomotor behavior. In order to determine what role the ocular oscillators play in controlling rhythmic behavior, the eyes were removed and locomotor activity was recorded during free runs and while entrained to light‐dark cycles. We find that eye removal leads to a disorganization of the free‐running locomotor rhythm, suggesting that the ocular oscillators are involved in timing this behavior. EyelessBullain the presence of light cycles exhibit locomotor rhythmicity but there is a switch from predominantly nocturnal to diurnal activity. While diurnal behavior in eyelessBullareveals the presence of extraocular photoreceptors, we presently find no evidence that a circadian pacemaker mediates this diurnal activ

ISSN:0022-104X    

DOI:10.1002/jez.1402240107

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

年代:1982

数据来源: WILEY

摘要:

AbstractCross‐reinnervation studies performed ex ovo with newly hatched chicks demonstrate that peripheral motor neurons control the phenotypic characteristics of avian muscles. The present experiments were designed to determine whether or not nerves play a similar role during the initial expression of muscle fiber types. Previous experiments indicated that differentiation of specific fiber types occurs during the first week of embryogenesis, temporally coincident with the penetration of nerves within muscle masses. These observations suggested that peripheral nerves may be associated with the initial differentiation of fiber types. To test this hypothesis directly, anterior limb buds of the chick embryo were rendered aneurogenic by deletion of the brachial segment of the neural tube. To ensure a completely aneurogenic environment for developing brachial muscles, surgery was performed at day 2 in ovo before the exit of ventral root fibers. Experimental and control embryos from Stage (St) 25 (4.5 d) through St 45 (19d) were analyzed histochemically by a silver‐cholinesterase reaction to detect nerves and by the myosin ATPase reaction, following alkali and acid preincubation, to determine the fiber type composition of the muscles. In addition, the total volume of aneurogenic and control muscles was compared. Results demonstrate that the characteristic myosin ATPase profiles of individual aneurogenic and innervated (control) muscles were identical throughout the entire period analyzed. Therefore, we conclude that these enzymic profiles are endogenously expressed and are not under neuronal control during early embryogenesis. Furthermore, the entire sequence of events from the migration of myogenic cells to the anterior limb bud through the division of the primary muscle masses to form individual brachial muscles proceeded on schedule in the absence of nerves. Since the growth of aneurogenic muscles was impaired, we conclude that during embryogenesis peripheral motor nerves are necessary initially for the proper growth of muscles and ultimately, for their survival. They are not involved, however, with either the initial formation or initial differentiation of individual brachial musc

ISSN:0022-104X    

DOI:10.1002/jez.1402240108

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

年代:1982

数据来源: WILEY

摘要:

AbstractIt has been proposed that movements of cells at the base of the developing wing cause the wing to rotate (Yander and Searls, '80a,b). It was suggested that rotation of the wing caused the dorsal muscle mass of the wing bud to become the posterior musculature of the proximal part of the wing. Rotation of the wing was investigated by grafting dorsal myogenic tissue from a wing labeled with tritiated thymidine into the dorsal myogenic region of an unlabeled wing in its original orientation. Grafts were made both with and without their original ectoderm. The location and shape of the graft was recorded at the time of the operation. After a period of growth and morphogenesis, the host wing and adjacent body wall were fixed, sectioned, and prepared as autoradiographs. The location of the grafted cells was determined by reconstructing the host wing and adjacent body wall. It was found that the graft increased in length on the axis of the humerus and did not increase rapidly on any other axis. During stage 25, a deep groove began to form ventral to somite 19 because of ventral and cranial movement of the lateral body wall proximal to the base of the wing. The distal border of this groove was recognized as the posterior margin of the proximal wing. If the graft extended to the base of the wing, the graft participated in the formation of this groove. Grafted cells on the distal border of the groove were on the posterior surface of the wing at the level of the humerus.

ISSN:0022-104X    

DOI:10.1002/jez.1402240109

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe ability of embryonic chick bone to respond to 25 hydroxy‐vitamin D3and 1,25 dihydroxyvitamin D3was assessed in organ culture. These metabolites were added to prelabeled chick embryo long‐bone explants, and the amount of calcium‐45 released into the medium after 24 or 48 h of hormone exposure was measured. For each time period a significant release of calcium‐45 from hormone‐treated bones was observed. The response to 25 hydroxyvitamin D3and 1,25 dihydroxyvitamin D3was always greater at 48 h and a clear dose‐dependency was established at this time as well. 1,25 dihydroxy vitamin D3was the more potent resorbing agent at all concentrations tested. The results from this study suggest that vitamin D metabolites may be involved in bone regulation in the c

ISSN:0022-104X    

DOI:10.1002/jez.1402240110

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe effect of estradiol on the spontaneous maturation of porcine oocytes was investigated. Cumulus‐enclosed (intact) and cumulus‐free (denuded) oocytes were cultured in the presence of estradiol‐17β (0 to 10μg/ml) in a chemically defined bicarbonate‐buffered medium that contained either dextran or BSA, or in a complex Hepes‐buffered medium that was supplemented with serum. After 24 hr, chromatin spreads were prepared and meiotic maturation was scored. The biochemical integrities of the cumulus cells were assessed by determination of the estradiol and progesterone content of spent media after culture of intact oocytes in the presence of 0.5 × 10−6M testosterone and 10 μg/ml follicle‐stimulating hormone.Estradiol did not significantly affect the onset of maturation of either intact or denuded oocytes that were cultured in medium containing either BSA or serum. In serum‐supplemented medium, however, the progression of maturation beyond metaphase I was significantly affected by the steroid in a dose‐dependent manner. The steroid significantly inhibited the release from meiotic arrest of both types of oocyte cultured in medium supplemented with dextran. Supplementation of all media with testosterone and FSH significantly stimulated the synthesis of estradiol by the cumulus cells, compared with that of control groups. The synthesis of progesterone, however, was significantly stimulated by testosterone and FSH only in the BSA and serum‐supplemented media. It is concluded that exogenous estradiol has the capacity to arrest meiosis in vitro but that this capacity can only be expressed if no exogenous protein(s) is present. In the absence of exogenous protein, progesterone synthesis by the adherent c

ISSN:0022-104X    

DOI:10.1002/jez.1402240111

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

年代:1982

数据来源: WILEY