alexa Vitamin A deficiency results in the dose-dependent acquisition of anterior character and shortening of the caudal hindbrain of the rat embryo.


Anatomy & Physiology: Current Research

Author(s): White JC, Highland M, Kaiser M, ClagettDame M

Abstract Share this page

Abstract The developing nervous system is particularly vulnerable to vitamin A deficiency. Retinoid has been proposed to be a posteriorizing factor during hindbrain development, although direct evidence in the mammalian embryo is lacking. In the present study, pregnant vitamin A-deficient (VAD) rats were fed purified diets containing varying levels of all-trans-retinoic acid (atRA; 0, 0.5, 1.5, 6, 12, 25, 50, 125, or 250 microg/g diet) or were supplemented with retinol. Hindbrain development was studied from embryonic day 10 to 12.5 ( approximately 6 to 40 somites). Normal morphogenesis was observed in all embryos from groups fed 250 microg atRA/g diet or retinol. The most caudal region of the hindbrain was the most sensitive to retinoid insufficiency, as evidenced by a loss of the hypoglossal nerve (cranial nerve XII) in embryos from the 125 microg atRA/g diet group. Further reduction of atRA to 50 microg/g diet led to the loss of cranial nerves IX, X, XI, and XII and associated sensory ganglia IX and X in all embryos as well as the loss of hindbrain segmentation caudal to the rhombomere (r) 3/4 border in a subset of embryos. Dysmorphic orthotopic otic vesicles or immature otic-like vesicles in both orthotopic and caudally ectopic locations were also observed. As the level of atRA was reduced, a loss of caudal hindbrain segmentation was observed in all embryos and the incidence of otic vesicle abnormalities increased. Perturbations in hindbrain segmentation, cranial nerve formation, and otic vesicle development were associated with abnormal patterning of the posterior hindbrain. Embryos from VAD dams fed between 0.5 and 50 microg atRA/g diet exhibited Hoxb-1 protein expression along the entire neural tube caudal to the r3/r4 border at a time when it should be restricted to r4. Krox-20 protein expression was expanded in r3 but absent or reduced in presumptive r5. Hoxd-4 mRNA expression was absent in the posterior hindbrain, and the rostral limit of Hoxb-5 protein expression in the neural tube was anteriorized, suggesting that the most posterior hindbrain region (r7/r8) had been deleted and/or improperly patterned. Thus, when limiting amounts of atRA are provided to VAD dams, the caudal portion of the hindbrain is shortened and possesses r4/r5-like characteristics, with this region finally exhibiting r4-like gene expression when retinoid is restricted even more severely. Thus, regions of the anterior hindbrain (i.e., r3 and r4) appear to be greatly expanded, whereas the posterior hindbrain (r5-r8) is reduced or absent. This work shows that retinoid plays a critical role in patterning, segmentation, and neurogenesis of the caudal hindbrain and serves as an essential posteriorizing signal for this region of the central nervous system in the mammal. Copyright 2000 Academic Press. This article was published in Dev Biol and referenced in Anatomy & Physiology: Current Research

Relevant Expert PPTs

Relevant Speaker PPTs

  • Seema Narayan
    A comparative study of the link between real exchange rate of ASEAN countries and fossil fuel prices
    PDF Version
  • Navinchandra G. Ashar
    Comparative study of techno-economic evaluation of the production of liquid Sulphur Di Oxide
    PDF Version
  • Wei Gong
    Wei Gong-Huazhong-University-of-Science-and-Technology-China-Probabilistic-seismic-hazard-assessment-for-the-pseudo-negative-stiffness-control-of- a-steel-base-isolated-building-A-comparative-study-
    PPT Version | PDF Version
  • Abdullah Altin
    PPT Version | PDF Version
  • Nahla A El-Wakil
    Comparative study of enzymatic and chemical denaturation of wheat gluten and their cellulosic nanocomposites
    PPT Version | PDF Version
  • Krzysztof Wieczerzak
    A comparative transcriptome provides candidate genes for determination the cause of males infertility.
    PPT Version | PDF Version
  • Flavia Secco Tavares de Souza
    A Comparative Study Among Elective Conventional Surgery, Urgency/Emergency Conventional Approaching and Elective Videolaparoscopic Surgery on the Treatment of Hospitalized Patients at First Surgeric Clinic of Federal Hospital of Bonsucesso with a Diagnostic of Colorectal adenocarcinoma, between January 2010 and December 2012
    PPT Version | PDF Version
  • Rajendra K Ray
    Comparative Study And Improvement Of Shallow-Water Models
    PPT Version | PDF Version
  • Nisreen E. Mahmoud
    Parasitological and comparative pathological studies on monogenean infestation of cultured sea bream (Sparus aurata, Sparidae) in Egypt.
    PPT Version | PDF Version

Recommended Conferences

Relevant Topics

Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version