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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID
Egr4tm1Jmi
targeted mutation 1, Jeffrey Milbrandt
MGI:2450146
Summary 1 genotype
Jump to Allelic Composition Genetic Background Genotype ID
hm1
Egr4tm1Jmi/Egr4tm1Jmi involves: C57BL/6 MGI:2658746


Genotype
MGI:2658746
hm1
Allelic
Composition
Egr4tm1Jmi/Egr4tm1Jmi
Genetic
Background
involves: C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Egr4tm1Jmi mutation (0 available); any Egr4 mutation (13 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
reproductive system
• adult homozygotes exhibit a significant reduction in the number of maturing spermatocytes
• homozygotes exhibit early apoptotic changes in early-mid pachytene spermatocytes that are often associated with significantly degenerated cells in the testis
• many germ cells display marked aggregation/margination of nuclear contents and early fragmentation of the cytoplasm
• ploidy analysis by flow cytometry confirmed that 70%-80% of primary spermatocytes are lost to apoptosis during prophase I of meiosis after chromosomal doubling
• male germ apoptosis precedes the onset of puberty and occurs during the first round of spermatogenesus in mutant mice
• moreover, the extent of spermatocyte apoptosis is not significantly altered in a p53-null background
• however, both spermatogonia and Sertoli cells appear morphologically intact in all tubules examined
• most seminiferous tubules contain highly degenerated cells that cannot be staged
• adult homozygotes display distortion of the seminiferous epithelium architecture
• mutant testes exhibit relatively small tubules with open lumina due to a significant reduction in the number of maturing spermatocytes
• mutant testes exhibit Leydig cell hyperplasia relative to wild-type testes
• adult homozygotes display microrchidia
• at >8 weeks of age, mutant testes weigh 43% of wild-type
• a 26% reduction in mutant testis weight is first evident at P14, after germ cells have entered the first round of spermatogenesis but prior to the onset of puberty
• male homozygotes exhibit a nearly complete germ cell maturation arrest at the early-mid pachytene stage
• while many early-mid pachytene spermatocytes appeear to degenerate, the maturation arrest is not complete, as some late pachytene spermatocytes are still identifiable
• most homozygotes contain frequent immature germ cells and negligible numbers of mature spermatozoa in their cauda epididymides
• however, a sufficient number of mature spermatozoa are still present for morphologcal analysis
• spermatozoa obtained from mutant cauda epididymides are significantly reduced in number and display a variety of structural defects
• mutant flagella are often sharply kinked, fragmented, or exhibit tightly coiled distal ends
• frequently, mutant sperm heads are either detached completely or bent sharply back on the flagellum to obscure the acrosomal cap
• 70%-80% of mutant primary spermatocytes fail to transgress the early-mid pachytene stage of meiotic prophase due to massive germ cell death
• male, but not female, homozygotes are infertile
• occasional male homozygotes sire very small litters (4-5 pups) but never with the frequency of wild-type males

endocrine/exocrine glands
• however, both spermatogonia and Sertoli cells appear morphologically intact in all tubules examined
• most seminiferous tubules contain highly degenerated cells that cannot be staged
• adult homozygotes display distortion of the seminiferous epithelium architecture
• mutant testes exhibit relatively small tubules with open lumina due to a significant reduction in the number of maturing spermatocytes
• mutant testes exhibit Leydig cell hyperplasia relative to wild-type testes
• adult homozygotes display microrchidia
• at >8 weeks of age, mutant testes weigh 43% of wild-type
• a 26% reduction in mutant testis weight is first evident at P14, after germ cells have entered the first round of spermatogenesis but prior to the onset of puberty

homeostasis/metabolism
N
• adult male homozygotes display no significant differences in serum LH and FSH levels relative to wild-type males, as measured by radioimmunoassays

cellular
• spermatozoa obtained from mutant cauda epididymides are significantly reduced in number and display a variety of structural defects
• mutant flagella are often sharply kinked, fragmented, or exhibit tightly coiled distal ends
• frequently, mutant sperm heads are either detached completely or bent sharply back on the flagellum to obscure the acrosomal cap
• adult homozygotes exhibit a significant reduction in the number of maturing spermatocytes
• most homozygotes contain frequent immature germ cells and negligible numbers of mature spermatozoa in their cauda epididymides
• however, a sufficient number of mature spermatozoa are still present for morphologcal analysis
• 70%-80% of mutant primary spermatocytes fail to transgress the early-mid pachytene stage of meiotic prophase due to massive germ cell death
• homozygotes exhibit early apoptotic changes in early-mid pachytene spermatocytes that are often associated with significantly degenerated cells in the testis
• many germ cells display marked aggregation/margination of nuclear contents and early fragmentation of the cytoplasm
• ploidy analysis by flow cytometry confirmed that 70%-80% of primary spermatocytes are lost to apoptosis during prophase I of meiosis after chromosomal doubling
• male germ apoptosis precedes the onset of puberty and occurs during the first round of spermatogenesus in mutant mice
• moreover, the extent of spermatocyte apoptosis is not significantly altered in a p53-null background





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last database update
11/19/2024
MGI 6.24
The Jackson Laboratory