Phenotypes Associated with This Genotype

Genotype
MGI:2176815

• Allelic Composition: Fgf8^tm1.1Mrt/Fgf8^tm1.2Mrt
• Genetic Background: involves: 129P2/OlaHsd

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

mortality/aging

prenatal lethality, incomplete penetrance ( J:45909 )

• at E18.5, only 50% of the expected number of compound heterozygotes are found

growth/size/body

decreased embryo size ( J:45909 )

• embryos are categorized into 3 groups determined by severity of phenotype; embryos are generally smaller than wild-type littermates in the least severely affected group 1

• in group 2, embryos are very small and developmentally delayed compared to littermates but mesoderm-derived structures are present

• group 3 embryos which are the most severely affected group resemble Fgf8^tm1.2Mrt homozygotes

embryo

abnormal rostral-caudal axis patterning ( J:45909 )

• many group 2 embryos display a failure of posterior development

decreased embryo size ( J:45909 )

• embryos are categorized into 3 groups determined by severity of phenotype; embryos are generally smaller than wild-type littermates in the least severely affected group 1

• in group 2, embryos are very small and developmentally delayed compared to littermates but mesoderm-derived structures are present

• group 3 embryos which are the most severely affected group resemble Fgf8^tm1.2Mrt homozygotes

nervous system

abnormal pituitary gland morphology ( J:178252 )

• mutants exhibit severe abnormalities in the pituitary gland

• at E17.5, 2 of 6 mutants show a substantial reduction of anterior pituitary tissue and absence of the posterior lobe while 4 of 6 mutants show a mild pituitary gland phenotype

small embryonic telencephalon ( J:45909 )

• vesicles are abnormally small in group 1 embryos

abnormal midbrain morphology ( J:45909 )

• defects are usually more severe than in Fgf^tm1.1 homozygotes

absent inferior colliculus ( J:45909 )

• inferior collicular (posterior midbrain) tissue is deleted in group 1 embryos

abnormal hypothalamus morphology ( J:178252 )

• reduction of arginine vasopressin and oxytocin neurons in the supraoptic, suprachiasmatic, and paraventricular nuclei

absent cerebellum ( J:45909 )

• cerebellar tissue (anterior hindbrain) is absent in group 1 embryos; defects are usually more severe than in Fgf^tm1.1 homozygotes

cardiovascular system

abnormal heart development ( J:45909 )

• many group 2 embryos display cardiac abnormalities

limbs/digits/tail

syndactyly ( J:45909 )

• fusion of two digits is often observed

craniofacial

abnormal craniofacial development ( J:45909 )

endocrine/exocrine glands

abnormal pituitary gland morphology ( J:178252 )

• mutants exhibit severe abnormalities in the pituitary gland

• at E17.5, 2 of 6 mutants show a substantial reduction of anterior pituitary tissue and absence of the posterior lobe while 4 of 6 mutants show a mild pituitary gland phenotype