摘要:

AbstractThe effects of trauma on antlers, pedicles and/or frontal bones in roe‐, red‐ and fallow‐deer during the period of antler growth were investigated. The following results were obtained: (1) antler regeneration originates from the osseous part of the pedicle or frontal bone and is not restricted to the hypothetical “Bildungssaum” or so‐called regenerative rim. (2) Unilateral trauma of a growing antler stimulates a trophic response on the control side only when the base of the pedicle, that is, the generative region of antler production, has been heavily injured. In such circumstances supernumerary and dislocated pedicles may be produced. Not infrequently the abnormality caused by unilateral trauma to the germinative bud may reappear in the next antler cycle in the same place but in a more intensified form. In general it may be found that there is a direct correlation between the trophic response to trauma and the stage of antler growth, i.e., the earlier the period of growth the more vigorous the trophic response to the trauma. Moreover, it may be that the antler cycle on the one pedicle may be accelerated or slowed down owing to trauma or other factors so far unknown. There are even cases on record where the antler on one side only may be affected differently by hormonal factors than the opposite side. All these findings have led the authors to the conclusion that each of the frontal bones, as a base for the pedicles and antlers, may have a center of antler stimulation of its own. It is assumed that in these centers (dispositions) a “pattern of antler form” is integrated. This is the only possible explanation for the memory of antler injuries on the one hand and the unilateral disturbances of antler growth on the other. It is suggested that the hormones which influence antler growth exert their effects via neural trophic centers and may thus be directed only to one antler or to a certain zone of it. Conversely, it is possible that the specific hormone may be prevented by the neural trophic centers from acting on the tissues of one antler or a certain zone of it. The site of such trophic centers is supposed to be t

ISSN:0022-104X    

DOI:10.1002/jez.1401590302

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe life stages ofAureliawere raised under controlled conditions in a chemically defined salt solution. Scyphistomae have thrived for three years in this medium, budding and strobilating normally. Ephyrae developed into mature medusae within a four month period. A description of all the life stages of aknownspecies of jellyfish was obtained for the first time.Laboratory cultured medusae underwent developmental changes very similar to medusae in nature. The development of new structures occurred in a chronological sequence which consistently appeared in this order: marginal veil and oral arms, circular canal, margin tentacles, marginal lappets and special sensory lappets, subgenital pits, eight‐partition scalloping of the bell, ruffling of the oral arms, and sexual products. Gastric filaments, nematocysts and mesogloea continually increased in number and amount throughout development.Laboratory cultured medusae differed from those developing in nature in that they (1) reached a maximum growth of 55 mm at the time of sexual maturation, (2) did not develop as many tentacles at the bell margin, and (3) did not yield as many planulae.It was not possible to correlate closely either the age or size of the medusae with the development of any specific morphological structure.All medusae underwent spontaneous deterioration. The extrusion of gastric filaments along with the release of sexual products indicated that medusae may starve to death since gastric filaments are believed necessary for digestion of food.The flexibility and variety of growth systems occurring inAureliaunder controlled conditions provide new opportunities for the study of basic mechanisms involved in normal and abnormal growt

ISSN:0022-104X    

DOI:10.1002/jez.1401590303

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

年代:1965

数据来源: WILEY

摘要:

AbstractRepresentatives of 30 species of fish were examined for their content of LDH isozymes. One major isozyme system was found in all fish. In addition, two minor systems restricted to eyes and to gonads were found in many fish. Fish may be classified into four groups on the basis of their possession of one, two, three, or five major isozymes of LDH. The major isozyme patterns can be attributed to the polymers of two protein subunits under the control of two genes, as in mammals and birds, but the variety of heteropolymers produced varies in different species. The fluke and other flatfish are exceptional in that they synthesize only one kind of subunit which polymerizes to form a single variety of LDH. All other fish produced at least two major isozymes presumably the homopolymers ofAandBsubunits. The three‐isozyme fish produce, in addition, a single heteropolymer. A few fish produce three heteropolymers and two homopolymers to produce the characteristic pattern of five isozymes seen in mammals.In populations of the whiting, which has five major isozymes, two mutant alleles at theBlocus were discovered. Each of these alleles produced polypeptides with characteristic electrophoretic mobilities. Consequently, heterozygous individuals contained more than 15 isozymes.A variety of minor isozymes that appear on zymograms may represent modifications of the major isozymes. However, the minor isozyme systems of the gonad and the eye seem to be genetically distinct molecular systems, separate from and in addition to the major isozyme syste

ISSN:0022-104X    

DOI:10.1002/jez.1401590304

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe ovaries of females homozygous for any of the mutant alleles of thefusedgene produce tumorous chambers. Tumor incidence increases with age, and the frequency of tumors infuovaries 0–12 days of age is six times that observed in the ovaries offu59females of the corresponding age. Ovaries offu/fuandfu59/fu59females were transplanted into hosts homozygous for the + allele offusedto determine if the extra‐ovarian environment has any relation to the rate at which tumors appear. The rates remain the same in each case indicating that the rate is a genetic characteristic of the cells of the ovary and is not affected by the extra‐ovarian enviro

ISSN:0022-104X    

DOI:10.1002/jez.1401590305

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe nerve fibers present at the amputation surface of the upper arm of the land stage and larval newt were counted and compared with values previously published by one of us on the adult. When expressed per unit area of surface, it was observed that the limb of the larva and the small land forms is more highly innervated than that of the adult. The values were 75.5, 47.6, and 27.7 fibers per (100 μ)2respectively for the larval, small land stage, and adult animals. The number of fibers per unit area of the larger land forms resembled that for the adult showing that the innervation ratio stabilizes at a time before the animal returns to water.Calculations were also made of the number of motor and sensory fibers in the individual brachial nerves of the younger animals. Assuming the same quantitative threshold of nerve fibers is required to evoke regeneration of the limb in the young animal as is needed in the adult, it was possible to predict the effectiveness of each nerve and nerve component in supplying the neural requirement for regeneration. For example, we found that nerve 5, ineffective in itself to cause regeneration in adults, should evoke regrowth in younger forms, particularly in larvae. The predicted results correspond with experimental ones already published in the literature. The quantitative studies reported herewith are evaluated and discussed against the background of the important action of the nerve in regeneration of a body part

ISSN:0022-104X    

DOI:10.1002/jez.1401590306

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe effects of hypophysectomy and of hormone treatments on the interrenal ofTilapia mossambicawere studied, utilizing measurements of mean interrenal nuclear diameter as an index of interrenal function.Hypophysectomy ofTilapiamaintained in isotonic Ringer's solution resulted in a significant decrease in interrenal nuclear diameter after 21 days. This decrease was prevented by treatment of hypophysectomized fish with mammalian ACTH. Mammalian ACTH significantly increased the interrenal nuclear diameters of intact fish maintained in fresh water, but failed to do so in intactTilapiakept in isotonic Ringer's solution.Administration of cortisol acetate to intactTilapiareduced the mean nuclear diameter of interrenal cells. The degree of response was both dose and time dependent. Administration of 0.04 mg/day of deoxycorticosterone acetate for 21 days also significantly reduced the mean interrenal nuclear diameter. Treatment with the same dose of DCA for only 14 days, or with a smaller dose for 21 days, failed to induce interrenal atrophy.These results suggest that a pituitary‐interrenal axis, resembling the pituitary‐adrenocortical axis of mammals, exists inTilapia mossamb

ISSN:0022-104X    

DOI:10.1002/jez.1401590307

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the spermatozoon of Ascidia nigra is described. The head of this sperm contains an elongated nucleus flanked and surrounded by a single large mitochondrion. No other mitochondria are present. An acrosome is seen to extend over a large portion of the nucleus. The tail shows the typical 9 + 2 arrangement of fibrils, and in some region carries fins.

ISSN:0022-104X    

DOI:10.1002/jez.1401590308

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

年代:1965

数据来源: WILEY

摘要:

AbstractMitochondria of rat sperm tail middle‐piece remain associated with the flagellum after penetration of the egg by the spermatozoon and during the time of the first cleavage. During two‐ to four‐cell stages the middle‐piece mitochondria gradually swell while they separate in large clusters from the axial filament. The swelling of the male mitochondrial elements becomes more extreme during the cleavage divisions, and they finally seem to disintegrate. Thus all mitochondria found in the developing rat embryo may originate from

ISSN:0022-104X    

DOI:10.1002/jez.1401590309

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

年代:1965

数据来源: WILEY

摘要:

AbstractThe spermatozoa ofAscidia nigracontain only one mitochondrion. Phase contrast and electron microscopical evidence is presented showing that the spermatozoon loses its mitochondrion before it enters the perivitelline space. Thus, in these organisms, the paternal mitochondrion plays no role in the development of the zygote and cannot contribute mitochondrial DNA to the genetic repertory of the zygote.

ISSN:0022-104X    

DOI:10.1002/jez.1401590310

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

年代:1965

数据来源: WILEY

摘要:

AbstractTritiated thymidine (H3‐T) autoradiography has been applied to the duodenal progenitor population (crypts of Lieberkühn) in four age groups of male Swiss albino mice to determine: (1) the size and distribution of the progenitor cell pool; and (2) to characterize the role of individual progenitor cells in previously reported age‐related alterations in the proliferative activity of the population.The progenitor cells which incorporated H3‐T extended from the first cell below the crypto‐villal junction to the last cell (Paneth) at the cryptal base in each age group. However, the majority of labeled progenitor cells were restricted to the central region of the crypt, while a smaller number was found in both the upper and basal portions. Thus, the crypt wall was divided into three zones according to the incidence of labeled cells; (1) zone of minimum cell proliferation (upper region), (2) zone of maximum cell proliferation (central region), and (3) zone of Paneth cells (basal region). The labeling incidence of the maximum zone was 3–5 times that of the minimum or Paneth regions.Comparison of the labeling incidence at the different ages revealed an age‐related decrease in the overall frequency of labeled cells throughout the crypt, and particularly in the maximum zone. Estimations of the progenitor cycle duration from the ratio of S‐phase duration to the DNA synthetic index revealed an increase in the progenitor cycle duration with age. It appears that the cycle duration increase, rather than a decrease in the size of the functional progenitor pool, may be the reason for theage‐related change in the proliferative activity.The labeling frequency of progenitor cells was least (about 1%) at the cryptovillal junction and highest (about 50%) in the central region of the crypt. It is concluded that factors in the microenvironment of the duodenal epithelial cell population may be regulating the proliferative activity of the

ISSN:0022-104X    

DOI:10.1002/jez.1401590311

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

年代:1965

数据来源: WILEY