In the developing human musculoskeletal system, cell death with macrophage accumulation occurs in the thigh muscle and interdigital area. To comprehensively clarify the distribution of macrophages, we immunohistochemically examined 16 pairs of upper and lower extremities without the hip joint (left and right sides) obtained from 8 human fetuses at approximately 10-15 weeks of gestation. Rather than in muscles, CD68-positive macrophages were densely distributed in loose connective tissues of the flexor aspects of the extremities, especially in the wrist, hand and foot. In contrast, no or fewer macrophages were evident in the shoulder and the extensor aspects of the extremities. The macrophages were not concentrated at the enthesis of the tendon and ligament, but tended to be arranged along other connective tissue fibers. Deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling revealed apoptosis in the hand lumbricalis muscles, but not in the area of macrophage accumulation. Likewise, podoplanin-positive lymphatic vessels were not localized to areas of macrophage accumulation. Re-organization of the connective tissue along and around the flexor tendons of the hand and foot, such as development of the bursa or tendon sheath at 10-15 weeks, might require the phagocytotic function of macrophages, although details of the mechanism remain unknown.
Apoptosis ; Cell Death ; Connective Tissue ; Deoxyuracil Nucleotides ; Deoxyuridine ; Extremities ; Fetus ; Foot ; Hand ; Hip Joint ; Humans ; Ligaments ; Lower Extremity ; Lymphatic Vessels ; Macrophages ; Muscles ; Musculoskeletal System ; Pregnancy ; Shoulder ; Tendons ; Thigh ; Wrist

BACKGROUND: Cis-AB is very rare among caucacians and found relatively often among Korean and Japanese populations. The molecular genetic characteristics of Japanese cis-AB were reported recently. All the Japanese cis-AB analyzed so far had identical polymorphisms. This work was performed to disclose the genetic polymorphisms in Korean cis-AB individuals. METHODS: DNA was extracted from 8 cis-AB Koreans. A and O transferase genes were amplified with GA0IN/GA14 allele-specific primer set, and B and cis-AB genes were amplified with GA0IN/GA13 allele-specific primer set. Restriction enzymes including BstPI, KpnI, BssHII, BsaHI, HapII, AluI, and MvaI were used for PCR-RFLP to find out the coexistence of O gene and to determine the nucleotides at nps 467, 526, 703, and 796. Exon 7 was divided into 2 regions and amplified to perform PCR-SSCP. RESULTS: All of the Korean cis-AB analyzed had identical genetic polymorphisms to those reported on Japanese cis-AB. PCR-RFLP with GA0IN/GA13 showed that all cis-AB samples had the allele with A-specific nucleotides at nps 526,703 and 796, and B-specific nucleotides at np 803. Other genetic polymorphisms showed that all of those with cis-AB allele had T at np 467 (leucine at amino acid position 156). CONCLUSION: Genetics polymorphisms reported on 29 Japanese cis-AB so far and 8 Koreans cis-AB analyzed in this study had identical mutations. This may imply that the cis-AB often found in Korea and Japan have single origin. It is plausible that a group of Korean people immigrated from the southwest part of Korea to the western part of Japan through a sea route in the past.
Alleles ; Asian Continental Ancestry Group ; DNA ; Exons ; Genetics ; Humans ; Japan ; Korea ; Molecular Biology* ; Nucleotides ; Polymorphism, Genetic ; Transferases