Variation in pattern of mystacial vibrissae in mice. A quantitative study of ICR stock and several inbred strains

We report on the variation in the pattern of mystacial vibrissae in ICR mice, of which one-half of the about 600 animals investigated showed one or more supernumerary whiskers (SWs). The SWs and their follicles--in all respects identical to the units of the standard pattern except for their smaller size--occurred at a restricted number of sites. In addition, a limited number of mice from two BALB/c strains were analyzed. Half of them also had one or more SWs, but mainly at one site. Mice of the C3H/HeJ and DBA/2J(a) strains were virtually without SWs, whereas animals from the NMRI strain were standard without exception. Nearly all animals of the C57BL/6J strain lacked between 1 and 4 vibrissae, always from one or two of the same adjacent sites. There was a slight overall predominance for the left side of the face to bear SWs and there was no clear-cut association with sex; the entire population was without obvious defects. The sites where extra or lacking whiskers occur are associated with the lines of fusion between the medial and the lateral nasal fold, and between the latter and the maxillary arch. Where tested, we always found a topologic equivalency between the pattern of the whisker follicles and the contralateral pattern of the "barrels"--multineuronal units in layer IV of the parietal cerebral cortex--whether the pattern was standard, "enriched," or lacking in elements. The data presented in this paper provided a basis for several studies carried out subsequently on animals that are the offspring of those characterized here, studies suggesting that the occurrence of supernumerary and of lacking whiskers has a genetic basis

Hair organ regeneration via the bioengineered hair follicular unit transplantation

Organ regenerative therapy aims to reproduce fully functional organs to replace organs that have been lost or damaged as a result of disease, injury, or aging. For the fully functional regeneration of ectodermal organs, a concept has been proposed in which a bioengineered organ is developed by reproducing the embryonic processes of organogenesis. Here, we show that a bioengineered hair follicle germ, which was reconstituted with embryonic skin-derived epithelial and mesenchymal cells and ectopically transplanted, was able to develop histologically correct hair follicles. The bioengineered hair follicles properly connected to the host skin epithelium by intracutaneous transplantation and reproduced the stem cell niche and hair cycles. The bioengineered hair follicles also autonomously connected with nerves and the arrector pili muscle at the permanent region and exhibited piloerection ability. Our findings indicate that the bioengineered hair follicles could restore physiological hair functions and could be applicable to surgical treatments for alopecia

Maturation of the neuronal metabolic response to vibrissa stimulation in the developing whisker-to-barrel pathway of the mouse

We examined functional maturation in the mouse whisker-to-barrel pathway from P2 (P0 is the day of birth) to adulthood using the autoradiographic deoxyglucose (DG) method. After intraperitoneal DG injection, left whiskers C1-3 and E1 were stimulated. Sections were cut transversely through the brainstem, and coronally or tangentially through the parietal cortex. After autoradiography, the sections were stained for Nissl or for cytochrome oxidase (CO) activity. In subnuclei caudalis and interpolaris of the spinal trigeminal nucleus ipsilateral to stimulation, DG uptake evoked by the deflection of whiskers C1-3 was present at P2; in subnucleus oralis, nucleus principalis and the contralateral nucleus ventrobasalis of the thalamus, at P4; and in the contralateral barrel cortex, at P7. The first stimulus-dependent DG uptake appeared a few days after the appearance of whisker-related patterns seen in the CO- or Nissl-stained sections. In subnuclei caudalis and interpolaris, areas of stimulus-dependent DG uptake were initially larger than the CO segments representing the stimulated whiskers. Later, areas of stimulus-dependent DG uptake and CO segments matched well. DG uptake evoked by the stimulation of whisker E1 appeared 2-3 days later than that evoked by stimulation of whiskers C1-3. In nucleus principalis, one large area of stimulus-dependent DG uptake covered the representations of the caudal whiskers of all five rows--an observation made at all ages studied. In thalamus, stimulus-dependent DG uptake was found laterally in nucleus ventrobasalis. In barrel cortex, at P7, stimulus-dependent DG uptake was restricted to layers III and IV, but covered more barrels than whiskers stimulated. At P9, a second spot of high DG uptake was seen in deep layer V in register with that in layers III and IV. From P10 onwards, stimulus-dependent DG uptake stretched from layer II to layer VI, and in layer IV, in which it was highest, it was restricted to the barrels C1-3 and E1. In all stations, stimulus-dependent DG uptake decreased in magnitude after P10. While the onset of stimulus-dependent DG uptake is the result of the establishment of functional projections up to that station, the subsequent changes in size of the responding areas may well be due to the partial elimination of terminals, the maturation of local inhibitory circuits, and/or the development of cortical projections to the nuclei of termination and to the thalamic relay

Selective breeding for variations in patterns of mystacial vibrissae of mice. Bilaterally symmetrical strains derived from ICR stock

The establishment of certain patterns of mystacial vibrissae in mice has been the aim of an extensive breeding program carried on in this laboratory since 1977. In a companion paper we have reported on variations in this pattern in an outbred population of ICR mice. Starting with 21 ICR animals we bred, mostly by brother-sister mating, for 13 bilaterally symmetric patterns of mystacial vibrissae characterized by the presence (or absence) of supernumerary whiskers (SWs). The strains are classified as follows: I, a mouse strain with the standard pattern; II, eight strains bred for the occurrence of SWs at a given site or sites; and III, four mouse strains bred for a maximal number of SWs in different regions of the whiskerpad. Commonly, SWs occur in regions that coincide with the zones of mergence between the three facial processes except for two class II strains in which we bred for SWs in the "straddler" row of vibrissae, and for one class III strain, in which we cultivated the tendency (that appeared late in our program) to have SWs at the crest of a facial process. For classes I and II we analyzed the results for about 18 generations in terms of "improvement," meaning an increase in the percentages of animals with the desired phenotype together with a decreased frequency of undesired SWs. For class III, success in breeding meant the increase of the mean number of the desired SWs. All results led to the same conclusion: there is a genetic basis for the occurrence of SWs. The side preference of a particular SW is not strain dependent. It disappears in those class I and II strains in which almost 100% of animals obtained the desired phenotype. The increase in number of SWs in one zone of mergence does not depend on the presence of SWs in the other. Where tested, we almost always found a representation of an SW in a topologically equivalent location within the "barrelfield" area of the somatosensory cerebral cortex. Except for some diseases early in the breeding program, and some side effects of inbreeding that were eliminated, the population was without obvious defects. Where tested, there was no correlation between the occurrence of SWs and sex. The observed variations in pattern of mystacial vibrissae and their genetic background led us to propose a morphogenetic model for the formation of the pattern of mystacial vibrissae

A magnetic device to stimulate selected whiskers of freely moving or restrained small rodents: its application in a deoxyglucose study

After receiving an intraperitoneal injection of [14C]2-deoxy-D-glucose (2-DG), a total of 28 mice which had pieces of metal wire glued to certain whiskers (all others were clipped) were exposed to magnetic field bursts. The stimulated whiskers were B1 (freely moving mice, set I) or whiskers C1-3 and E1 (restrained mice, set II) on the left side. In set I, stimulated mice were compared with animals of various control groups. Autoradiography demonstrated an activation of columnar shape overlying the presumed corresponding barrel contralateral to stimulation; in a part of the ipsilateral barrelfield, 2-DG uptake was depressed significantly. In the subnuclei caudalis and interpolaris of the trigeminal brainstem complex a spot of activation was observed ipsilaterally but there was no depression contralaterally. Whereas several animals of the control groups showed some aspects of these responses, they were consistent only in stimulated mice. In set II, animals received stimulation with different intensities. 2-DG uptake was higher in barrels C1-3 than in E1. It increased with increasing intensity. The same observations were made in two nuclei of termination. The device we describe here can be used to study stimulus-specific responses at various levels of the somatosensory pathway