摘要:

AbstractExisting data on integumental nerve endings provide a basis for classification of the visible epidermal appendages (hairs and dermatoglyphic pads) in mice. Hairs that have long tips (tylotrichs and bristles) are surrounded by large encapsulated cylinders of coarse nerve fibers. Half of these hairs (tylotrichs) are associated with disk‐shaped dermatoglyphic pads, which contain innervated Merkel cells. Hairs that have short tips are surrounded by small cylinders of fine nerve fibers, but contiguous dermatoglyphic pads and dermal capsules are missing. Constrictions in the shafts of short‐tipped hairs vary unpredictably and are not readily correlated with nerve endings.Analysis of the distribution, structure and physiology of nerve endings and dermatoglyphic pads makes possible (1) the recognition of meaningful features of hair structure (e.g., contour of the tip) that are involved in the transmission of mechanical energy to tactile receptors, and (2) the disregard of equivocal features of hair structure (e.g., 1 constriction in the shaft), which vary between the sexes, among body regions and among inbred stra

ISSN:0022-104X    

DOI:10.1002/jez.1401800302

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

年代:1972

数据来源: WILEY

摘要:

AbstractFrom 88 superovulated, mated CFI (Carworth) females, 2643 eggs were collected at two hourly intervals between 12 and 36 hours after administration of human chorionic gonadotrophin and then fixed, stained and examined as whole‐mounts by light microscopy. Mating and ovulation were essentially complete at 10 and 14 hours respectively.Metaphase II oocytes continued to decrease in number until 20 hours. Telophase II, a maximum at 16 hours (22% of all oocytes), was not seen after 20 hours. Pronuclei first appeared at 16 hours and at 24 hours, 87% of the ova were pronuclear. Metaphase of first cleavage, first detected at 28 hours, represented 17% of the ova at 32 hours. The first cleavage division occurred between 30 and 34 hours.The pronuclear chromatin network, which is always visible, is more diffuse in the larger, male pronucleus. During first cleavage prophase, the chromatin strands shorten and distinct chromosomes appear, those of male origin being less condensed. The two chromosome groups then combine to form first cleavage metaphase. Pronuclear fusion was not observed.Twenty‐three per cent of the ova had not undergone first cleavage by 36 hours: 6% were at earlier stages and presumably arrested while 14% were fragmented or had degenerated metaphase II chromosomes. Anomalies of oocyte maturation and fertilization accounted for 1.6% of all

ISSN:0022-104X    

DOI:10.1002/jez.1401800303

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

年代:1972

数据来源: WILEY

摘要:

AbstractChloramphenicol (CAP) produced an unusual cleavage anomaly inRana pipiensembryos involving re‐fusion of normal looking 6 to 12 hour blastomeres into irregularly shaped syncytial mounds. This occurred whether the CAP was added then or earlier. The condition was usually terminal, but often at lower doses or following CAP removal the mounts re‐cleaved and the embryos resumed development. Preliminary histological verification of blastomere fusion has been obtained.The same anomaly was produced by two other inhibitors, rotenone and the L‐isomer of CAP. These are without effect on mitochondrial protein synthesis in other systems but do share with high doses of D‐CAP a direct inhibition of respiration at the NADH oxidase level. Another such inhibitor, amytal, failed to affect cleavage, presumably because of poor penetration. Instead, amytal produced uniform developmental arrest at later stages characteristic for each dose. Similar but less uniform results were obtained with lower doses of D‐ and L‐CAP, rotenone, cyanide, and dinitrophenol. All of these, however, also produced cleavage arrest at higher doses, including prevention of first cleavage altogether at high enough concentrations of each.This disagrees with the older literature in the case of cyanide, to which early cleavage is purported to be insensitive and the onset of gastrulation unusually sensitive. There is also an apparent conflict between our cyanide‐rotenonechloramphenicol results, suggesting that cleavage is dependent on respiration, and the work of others on cleavage under anaerobiosis, suggesting not. Several hypotheses which would resolve this conflict, including that of an oxidative reserve in the eggs, are presented

ISSN:0022-104X    

DOI:10.1002/jez.1401800304

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe effects of a new dominant gene in the rat are described. This gene, restricted (Hr e), causes a marked restriction of the colored areas of the body in the hooded, irish and self color patterns. Males with this restricted color pattern (Re) exhibit testicular tubular dysgenesis with consequent sterility, and a slightly reduced growth rate. The histological structure of the testis is described. Various experimental studies with the Re males are presented. These studies indicate that the cause of the sterility is a relative insensitivity of the germinal epithelium to pituitary follice‐stimulating hormone. There is a high incidence of heterochromia in Re rats with cream coat color and ruby ey

ISSN:0022-104X    

DOI:10.1002/jez.1401800305

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

年代:1972

数据来源: WILEY

摘要:

Abstract3‐acetylpyridine (3AP) causes severe muscular hypoplasiain vivoand seems to potentiate chondrogenic expression of limb bud cellsin vitro. In both cases nicotinamide completely relieves these effects. In cell cultures, 3AP causes a substantial drop in nicotinamide incorporation. This decreased incorporation represents not only decreased cellular pools of nicotinamide but also decreased DPN‐TPN pools. 3AP also decreases the rate of RNA, protein, and mucopolysaccharide synthesis. 3AP does not affect the rate of DNA synthesis which is constantly decreasing as chondrogenic expression increases. Even though the rates of macromolecular synthesis seem to be reduced, the specific activity of an obligatory enzyme for mucopolysaccharide assembly, UDP glucose pyrophosphorylase, dramatically increases with 3AP‐treatment. This is interpreted to mean that 3AP potentiates of cartilage synthesizing machinery which is observed as a potentiation of chondrogenic expression. These data are discussed with regard to nicotinamide's proposed role in affecting the development of chick limb mesodermal cells into muscle and cartilage producing phenotypes. It is proposed that alterations in local concentrations of essential molecules like nicotinamide, DPN, or TPN can control phenotypic expre

ISSN:0022-104X    

DOI:10.1002/jez.1401800306

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

年代:1972

数据来源: WILEY

摘要:

AbstractLiving lungfish (Osteichthyes: Dipnoi) are known to have a very large cell size and unusually large quantitities of DNA per cell (up to 40 times the mammalian content). The pattern of evolution of cell size in fossil Dipnoi has been examined in order to see what light it might possibly shed on the question of the origin and evolutionary significance of DNA multiplication in Dipnoi. In the Devonian, cell size was low and it increased only in the Carboniferous when the major dipnoan morphological and taxonomic diversifications were ebbing. If it can be shown that there is a functional relationship between cell size and DNA content, then the data suggest that increase in cellular DNA content have a retarding rather than stimulating effect on dipnoan evolution. Since large cell size and (by inference) high cellular DNA content are not a primary feature of the dipnoan stock, it is suggested that in those other vertebrates, such as certain amphibians, which show the same phenomenon, it is also a secondary feature.

ISSN:0022-104X    

DOI:10.1002/jez.1401800307

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

年代:1972

数据来源: WILEY

摘要:

AbstractA chromatographic analysis of the blood from seven species of turtles, representing four families, has revealed that all animals contained multiple hemoglobins. Members of the Emydidae family had two major components separated by a minor one. There was some variation to this pattern in the box turtles (Terrapenes). The musk, soft shelled, and the snapping turtles examined had three, five, and four hemoglobins respectively. In general, electrophoresis of these proteins in starch gels confirmed the results obtained from DEAE cellulose chromatography in minicolumns.Hemoglobins from the painted and Cumberland turtles were found to be quite resistant to dimerization on aging and to alkali denaturation. These proteins from the box turtles were seen to be moderately resistant to both types of molecular modification, while those from the musk, the soft shelled, and the snapping turtles polymerized readily on aging and denatured readily in alkali.

ISSN:0022-104X    

DOI:10.1002/jez.1401800308

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

年代:1972

数据来源: WILEY

摘要:

AbstractTadpoles of the bullfrog,Rana catesbiana, lose the ability to regenerate limbs at a very early stage of development. Non‐regenerating limbs either show rapid healing of connective tissue over the cut surface with no breakdown of skeletal structures, or else show dedifferentiative processes in the cartilage but the rudimentary blastema formed does not proliferate, and becomes separated from the epidermis by the regrowth of the connective tissue layer. This condition is termed the “critical stage.” When tadpoles were treated with NGF, enlargement of spinal ganglia resulted due to an increase in cell number. The density of nerve fibers in the limbs was likewise increased. This increase in nerve supply to the limbs resulted in a greater incidence of critical stage limbs over non‐regenerating ones, and in several cases, produced limbs which appeared histologically to be, in fact, regen

ISSN:0022-104X    

DOI:10.1002/jez.1401800309

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe histological organization and cytology of the submandibular glands of male and female Mongolian gerbils were described. A sexual dimorphism in the glands, limited specifically to the serous tubules, was noted. In the male, gonadectomy, propylthiouracil administration and a combination of the two treatments resulted in significantly reduced serous tubule diameters. Such reduction was accompanied by a decrease in the number of cells per tubule without any change in the height of individual serous cells. In the female similar treatments were without effect on these parameters of the serous tubules. Experimental treatments did not affect the cytology or the periodic acid‐Schiff and Alcian blue reactions of the submandibular glands in either se

ISSN:0022-104X    

DOI:10.1002/jez.1401800310

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

年代:1972

数据来源: WILEY

摘要:

AbstractRabbits were immunized with vaginal epithelium from ovariectomized and estradiol‐injected adult mice. A crude IgG solution was prepared from the immune serum and was used for immunofluorescence studies (indirect method) of the appearance of antigen(s) specific for the vaginal epithelium during the differentiation of the cervicovaginal epithelium in neonatal mice. In neonatal untreated mice, the appearance of the antigen could be correlated with the mitotic activity and morphological transformation of the vaginal epithelium.Estradiol injected into neonatal mice had a two‐fold effect: it caused a precocious appearance of visible specific antigen in the untransformed pseudostratified cervicovaginal epithelium; however, in some mice it prevented the appearance of any visible antigen in the cervical epithelium, possibly by way of its inhibiting effect on cell divisions in this region. It is suggested that the epithelial cells must pass a “crucial mitosis” before being able to synthesize the antigen.The distribution of the antigen was also studied in immature and adult ovariectomized and estradiol injected mice. Estradiol strongly increased the small amount of antigen seen in the superficial cell layer of ovariectomized

ISSN:0022-104X    

DOI:10.1002/jez.1401800311

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

年代:1972

数据来源: WILEY