|Embryology - 18 Oct 2018 Expand to Translate|
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The rat (taxon - rattus) is readily available as inbred, outbred and mutant strains. They have been generally beaten as a model by their rodent mice brethren, as the molecular tools that became available (stem cells, knockout genes, etc).
Rat embryos do have the advantage of being much larger than mouse embryos and easy to breed. Another advantage of rats is in vision development studies, as that retinal development continues postnatally (most vertebrate neurological systems are difficult to access during periods of development). Rat development is also generally 1 day behind that of mouse. (The table below gives details relating to the staging of rat development). Below this are a list of internet resources relating to the rat.
|Rat Links: rat | Rat Stages | Rat Timeline | Category:Rat|
Some Recent Findings
|More recent papers|
This table shows an automated computer PubMed search using the listed sub-heading term.
References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.
Rat Estrous Cycle
See the review of the rat estrous cycle. One of the best characterised polyestrous reproductive cycles, though different species of rats may differ in reproduction. In general, puberty occurs at 6-8 weeks when the estrous cycle commences each cycle is 4-5 days. The estrous cycle is polyestrous, more than one estrous cycle during a specific yearly time, with an estrous period of approximately 12 hours.
Species Stages Comparison
The table below gives an approximate comparison of human, mouse and rat embryos based upon Carnegie staging.
|Note these Carnegie stages are only approximate day timings for average of embryos. Links: Carnegie Stage Comparison|
|Postnatal Animal Models||mouse||rat||pig|
|Pregnancy period (days)||18 – 21||21 – 23||110 – 118|
|Placenta type|| Discoidal, decidual
| Discoidal, decidual
|Litter size||6 – 12||6 – 15||11 – 16|
|Birth weight (g)||0.5 – 1.5||3 – 5||900 – 1600|
|Weaning weight male/female (g)||18 – 25/16 – 25||55 – 90/45 – 80||6000 – 8000|
|Suckling period (days)||21–28||21||28–49|
|Solid diet beginning (days)||10||12||12 – 15|
|Puberty male/female (week)||4 – 6/5||6/6 – 8||20 – 28|
|Life expectancy (years)||1 - 2||2 - 3||14 – 18|
|Table data - Otis and Brent (1954) Links: timeline|
Rat oocytes showing metaphase plate
- Links: Rat Timeline
For review of the rat placenta.
Adrenal and Gonad Development
Adrenal and gonad steroidogenic factor 1 expression
- Casanova EA, Okoniewski MJ & Cinelli P. (2012). Cross-species genome wide expression analysis during pluripotent cell determination in mouse and rat preimplantation embryos. PLoS ONE , 7, e47107. PMID: 23077551 DOI.
- Hamanaka S, Yamaguchi T, Kobayashi T, Kato-Itoh M, Yamazaki S, Sato H, Umino A, Wakiyama Y, Arai M, Sanbo M, Hirabayashi M & Nakauchi H. (2011). Generation of germline-competent rat induced pluripotent stem cells. PLoS ONE , 6, e22008. PMID: 21789202 DOI.
- Fujinaga M, Brown NA & Baden JM. (1992). Comparison of staging systems for the gastrulation and early neurulation period in rodents: a proposed new system. Teratology , 46, 183-90. PMID: 1440421 DOI.
- Hubscher CH, Brooks DL & Johnson JR. (2005). A quantitative method for assessing stages of the rat estrous cycle. Biotech Histochem , 80, 79-87. PMID: 16195173 DOI.
- Otis EM and Brent R. Equivalent ages in mouse and human embryos. (1954) Anat Rec. 120(1):33-63. PMID 13207763
- Webb RL, Findlay KA, Green MA, Beckett TL & Murphy MP. (2010). Efficient activation of reconstructed rat embryos by cyclin-dependent kinase inhibitors. PLoS ONE , 5, e9799. PMID: 20333307 DOI.
- Furukawa S, Hayashi S, Usuda K, Abe M, Hagio S & Ogawa I. (2011). Toxicological pathology in the rat placenta. J Toxicol Pathol , 24, 95-111. PMID: 22272049 DOI.
- Val P, Lefrançois-Martinez AM, Veyssière G & Martinez A. (2003). SF-1 a key player in the development and differentiation of steroidogenic tissues. Nucl. Recept. , 1, 8. PMID: 14594453 DOI.
Kito S, Yano H, Ohta Y & Tsukamoto S. (2010). Superovulatory response, oocyte spontaneous activation, and embryo development in WMN/Nrs inbred rats. Exp. Anim. , 59, 35-45. PMID: 20224168
Ahmed RP, Haider KH, Shujia J, Afzal MR & Ashraf M. (2010). Sonic Hedgehog gene delivery to the rodent heart promotes angiogenesis via iNOS/netrin-1/PKC pathway. PLoS ONE , 5, e8576. PMID: 20052412 DOI.
Search Pubmed: Rat Development
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
- Rat Genome Database RGD