All Phenotypes Thrb<tm4Few> MGI Mouse

increased thyrotroph cell number ( J:85158 )

• the number of anterior pituitary cells expressing the TSH-beta subunit is increased by 1.3 fold over control animals

• an overall enlargement is observed

abnormal pituitary gland physiology ( J:85158 )

• after daily intraperitoneal supplementation with excess injected triiodothyronine (T₃) hormone, expression of serum TSH and TSH subunit mRNA levels were not suppressed, indicating severely compromised feedback regulation in the pituitary by thyroid hormone

increased circulating thyroid-stimulating hormone level ( J:85158 )

• basal serum thyroid-stimulating hormone levels are increased 20-fold compared to control animals, suggestive of central thyroid hormone resistance

abnormal retina cone cell morphology ( J:85158 )

• lack of M opsin (found in green cones)

• significantly increased levels of S opsin (found in blue cones) in the dorsal retina to levels roughly equivalent to ventral retina

• increased and more uniform distribution of S opsin

abnormal cochlea morphology ( J:85158 )

decreased cochlear outer hair cell number ( J:85158 )

• a significant loss of outer hair cells in the basal third of the cochlea is seen; in the areas corresponding to the highest frequency regions, no outer hair cells remain

abnormal pillar cell morphology ( J:85158 )

• abnormalities in the position of the outer pillar feet are seen

degeneration of organ of Corti supporting cells ( J:85158 )

• a collapse of the outermost supporting cells of the cochlea is seen

spiral ligament degeneration ( J:85158 )

• in the basal half of the cochlea, fibrocyte degeneration in the spiral ligament is seen

abnormal tectorial membrane morphology ( J:85158 )

• abnormally shaped tectorial membrane

enlarged tectorial membrane ( J:85158 )

• enlarged membrane

increased or absent threshold for auditory brainstem response ( J:85158 )

• ABR threshold elevations of 60 dB over controls are seen at all frequencies

increased or absent distortion product otoacoustic emission threshold ( J:85158 )

• significantly elevated thresholds are seen at frequencies greater than ~10kHz

absent distortion product otoacoustic emissions ( J:85158 )

• 7 of 14 mice exhibited no DPOAE responses at the highest sound pressure level tested

sensorineural hearing loss ( J:85158 )

• profound hearing losses with threshold elevations of approximately 60dB at all test frequencies