Arch Oral Biol. 2005 Feb;50(2):219-25. Epub 2005 Jan 04.
The supernumerary cheek tooth in tabby/EDA mice-a reminiscence of the premolar in mouse ancestors.
Peterkova R, Lesot H, Viriot L, Peterka M.
Department of Teratology, Institute of Experimental Medicine, Academy of Sciences CR, Videnska 1083, 14220 Prague, Czech Republic.
OBJECTIVE:: A supernumerary cheek tooth occurs mesially to the first molar in tabby/EDA (Ta) mice affected by hypohidrotic ectodermal dysplasia. The supernumerary tooth (S) has been hypothetically homologized to the premolar, which has disappeared during mouse evolution. DESIGN:: This hypothesis was tested using available morphological data on the lower cheek teeth in wild type (WT) and Ta mice. RESULTS:: The presence of S is accompanied by a reduction in the mesial portion of the M(1) in mutant mice. 3D reconstructions suggest that the S in Ta homo/hemizygous embryos originates from a split off the mesial portion of the first molar (M(1)) cap. In WT embryos, two vestigial tooth primordia are transiently distinct in front of the M(1). The distal vestige has the form of a wide bud and participates during the development of the mesial portion of the M(1). This bud has been homologized with the vestigial primordium of the fourth premolar of mouse ancestors. The premolar disappearance coincided with a mesial lengthening of the M(1) during mouse evolution. The incorporation of the distal premolar vestige into the mesial part of the M(1) in WT embryos can be regarded as a repetition of the premolar disappearance during evolution. CONCLUSION:: Ontogenetic and phylogenetic data support that the S in Ta mice arises due to the segregation of the distal premolar vestige from the molar dentition and thus represents an evolutionary throwback (atavism).
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15721153
The supernumerary cheek tooth in tabby/EDA mice-a reminiscence of the premolar in mouse ancestors.
Peterkova R, Lesot H, Viriot L, Peterka M.
Department of Teratology, Institute of Experimental Medicine, Academy of Sciences CR, Videnska 1083, 14220 Prague, Czech Republic.
OBJECTIVE:: A supernumerary cheek tooth occurs mesially to the first molar in tabby/EDA (Ta) mice affected by hypohidrotic ectodermal dysplasia. The supernumerary tooth (S) has been hypothetically homologized to the premolar, which has disappeared during mouse evolution. DESIGN:: This hypothesis was tested using available morphological data on the lower cheek teeth in wild type (WT) and Ta mice. RESULTS:: The presence of S is accompanied by a reduction in the mesial portion of the M(1) in mutant mice. 3D reconstructions suggest that the S in Ta homo/hemizygous embryos originates from a split off the mesial portion of the first molar (M(1)) cap. In WT embryos, two vestigial tooth primordia are transiently distinct in front of the M(1). The distal vestige has the form of a wide bud and participates during the development of the mesial portion of the M(1). This bud has been homologized with the vestigial primordium of the fourth premolar of mouse ancestors. The premolar disappearance coincided with a mesial lengthening of the M(1) during mouse evolution. The incorporation of the distal premolar vestige into the mesial part of the M(1) in WT embryos can be regarded as a repetition of the premolar disappearance during evolution. CONCLUSION:: Ontogenetic and phylogenetic data support that the S in Ta mice arises due to the segregation of the distal premolar vestige from the molar dentition and thus represents an evolutionary throwback (atavism).
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15721153
Vastaukset 4
Vanhimmat
Ettei pääse unohtumaan, niin vastasin kyselyysi aikaisemmassa avauksessani.
http://keskustelu.suomi24.fi/show.fcgi?category=1000000000000003&conference=1500000000000073&posting=22000000006966327
En ole englanninkielisestä versiosta löytänyt mainintaa.
En nyt äkkiä muista ulkoa sivunumeroa, mutta lausahdus on suomenkielisessä versiossa kappaleessa, joka on otsikoitu ja lihavoitu sanalla Embryologia. Tarkistan vielä sivunumeron ja laitan sen maanantaina tänne.
Onpa jännä juttu, jos suomentaja on mennyt lisäilemään tekstiä kirjaan. Tuntuisi kyllä oudolta ja asiattomalta, jos näin on.
Mayrin kirjan embryologiaa käsittelevä kappale alkaa sivulta 57 kirjan suomenkielisessä versiossa. Poimimani sitaatti löytyy sitten sivulta 60 lauseessa, jossa viitataan kuvaan 2.9 sivulla 59:
” Merirokon toukat ovat hyvin samankaltaisia kuin äyriäisten toukat ( kuva 2.9) ja sikiöillä on havaittu tuhansissa tapauksissa esimuodolta polveutuneita rakennelmia, joita ei kuitenkaan löydy enää aikuiselta yksilöltä.”
Tässä kohtaa alkaa kappalejako ja seuraavassa kappaleessa kerrotaan mitä virkaa näillä samankaltaisilla katoavilla rakenteilla on; kerrotaan kuinka ne organisoivat sikiön rakenteita siirryttäessä eteenpäin yksilönkehityksessä (rekapitulaatio, siis).