Postnatal development of hypoplastic thymus in semi-lethal dwarf pet/pet males.
The petit rat (pet/pet) is a new semi-lethal dwarf mutant with anomalies in the thymus and testes, defects inherited as a single autosomal recessive trait. At birth, these pet/pet rats show low birth weight and extremely small thymuses; at 140 days of age, their thymuses show abnormal involution. In the present study, we examined early postnatal development of hypoplastic pet/pet thymuses. In addition to being hypoplastic at birth, pet/pet thymus growth was almost completely impaired during the early postnatal period. As shown by cellular incorporation of BrdU, the mitotic activity was lower in pet/pet than in normal thymuses, and terminal deoxynucleotidyl transferase dUTP nick end labeling assays showed that apoptosis occurred more often in pet/pet than in normal thymus cells during the first few days after birth. These results indicate that postnatal development of the hypoplastic pet/pet thymus is defective due to the reduced proliferation and increased apoptosis of thymic cells.
Laboratory of Veterinary Physiology, Nippon Veterinary and Life Science University, Tokyo 180–8602, Japan.
Junko
J
Chiba
Hiroetsu
H
Suzuki
Hiroaki
H
Aoyama
Kentaro
K
Katayama
Katsushi
K
Suzuki
D000015:Abnormalities, Multiple / Q000235:genetics / Q000473:pathology*; D000818:Animals; D004392:Dwarfism / Q000235:genetics*; D008297:Male; D008938:Mitosis; D051381:Rats; D013950:Thymus Gland / Q000002:abnormalities* / Q000166:cytology / Q000254:growth & development*