Harderian gland dependency of immunoglobulin A production in the lacrimal fluid of chicken

Involvement of the Harderian gland (HG) in the production of lacrimal immunoglobulin (especially IgA) was investigated. The lacrimal concentration of each immunoglobulin class was not affected by surgical bursectomy but was reduced by cyclophosphamide (CY) and testosterone (TP) treatments. Surgical removal of the Harderian gland caused a remarkable reduction of both the lacrimal concentration of each immunoglobulin class and the specific antibody titre, and and IgA was almost undetectable. The lacrimal concentration of each immunoglobulin class, as well as the specific antibody titre, was not affected by surgical removal of the Lacrimal gland (LG). The route of antigen administration produced no difference in the class of lacrimal immunoglobulin produced. The results indicate that the production of immunoglobulin in chicken tears may be dependent on the HG and that lacrimal immunoglobulin may be synthesized and secreted locally in the HG. Lymphocytes of the HG are of bursa of Fabricius origin and are seeded into the HG prior to hatching and its lymphocytes do not appear to be involved in systemic immunity.     

Comparative chromosome mapping of sex-linked genes and identification of sex chromosomal rearrangements in the Japanese wrinkled frog (Rana rugosa, Ranidae) with ZW and XY sex chromosome systems

There are regional variations of sex chromosome morphologies in the Japanese wrinkled frog, Rana rugosa (2n = 26): heterogametic ZZ/ZW-type and XX/XY-type sex chromosomes, and two different types of homomorphic sex chromosomes. To search for homology between the ZW and XY sex chromosomes and the chromosome rearrangements that have occurred during sex chromosomal differentiation in R. rugosa, we performed chromosome mapping of sexual differentiation genes for R. rugosa by FISH. Three genes, AR, SF-1/Ad4BP and Sox3, were localized to both the ZW and XY chromosomes, and their locations were all different between the Z and W and between the X and Y. AR and SF-1/Ad4BP were located on the short arms of the W and X and the long arms of Z and Y, and Sox3 was mapped to the different locations on the long arms between the Z and W and between the X and Y, probably as a result of multiple rearrangements that occurred during the process of sex chromosome differentiation. However, the chromosomal locations of three genes were almost consistent between the Z and Y and between the W and X, indicating that the Z and Y chromosomes and the W and X chromosomes were respectively derived from the same origins. Dmrt1, which is located on avian sex chromosomes, was localized to autosomes in R. rugosa with both the ZW and XY sex chromosomes, suggesting that Dmrt1 might not be related to sex determination in this species.     

De novo interstitial deletion of 4q[46,XX,del(4)(q27q28.2)] with intact blood group-MN locus,confining its locus to 4q28.2–4q31.1

We report a malformed female infant withde novo interstitial deletion of 4q[46,XX,del(4)(q27q28.2)]. The MN blood type analysis of the family members showed that the patient had an intact blood group-MN locus. The locus of the gene responsible for the MN antigen activity is confined to a 4q28.2–4q31.1 segment on the basis of the result of this patient and the previous mapping data.     

Hepatic microvascular development in relation to the morphogenesis of hepatocellular plates in neonatal rats

The development of hepatic microvascular heterogeneity after birth, and its temporal relationship to the development of parenchymal cell plates have received little attention. As a result, the morphogenesis of some of the parameters contributing to this heterogeneity in suckling and weaned rats was studied as a function of time between postpartum days 4 and 30 using in vivo light microscopic, electron microscopic, and immunocytochemical methods. During the early suckling period, the sinusoid network is highly anastomotic, with little evidence of zonation, and the parenchymal cell plates contain multiple cells and are irregularly arranged throughout the lobule. Sinusoidal endothelial fenestration is sparse at 4 days, but phagocytic Kupffer cell (KC) function already exists and exhibits zonal heterogeneity, with more cells located in the periportal zone. With increasing age, endothelial fenestrae increase and organize as sieve plates. Widened centrilobular radial sinusoids form through a loss ("drop-out") of intersinusoidal sinusoids (ISS). Concomitantly, the associated cell plates straighten and become one cell thick. Hepatocyte DNA synthesis and mitosis are higher in the periportal zone, which retains thickened cell plates and anastomotic sinusoids. The centrilobular sinusoids may widen to accommodate the increased volume of blood that results from the loss of ISS as well as the increased numbers of periportal sinusoids containing flow that feed these vessels. KC phagocytic activity increases during the suckling period concomitant with an increase of gut-derived endotoxin in the portal blood, which suggests that the KCs may be releasing mediators that affect sinusoid diameter, blood flow, endothelial fenestration, and perhaps parenchymal growth either directly or through the stimulation of growth factors.     

Increased osteocyte apoptosis during the development of femoral head osteonecrosis in spontaneously hypertensive rats

We investigated the presence of osteocyte apoptosis in the necrotic trabeculae of the femoral head of spontaneously hypertensive rat (SHR) using the in situ nick end labeling (TUNEL) method and transmission electron microscopy. The occurrence of osteonecrosis and ossification disturbance was significantly higher in SHR compared with Wistar Kyoto (WKY) rats, and Wistar (WT) rats used as control animals (P < 0.01). A high population of TUNEL positive osteocytes was detected mainly in 10- and 15-week-old SHRs. Sectioned examination of the femoral head of SHRs and WKY rats by electron microscopy revealed apoptotic cell appearances such as aggregation of chromatin particles and lipid formation. In contrast, a positive reaction was significantly lower in osteocytes in the femoral heads of WT rats (P < 0.01). Our results indicate that apoptosis forms an important component of the global pathologic process affecting the femoral head of SHR, which leads to osteonecrosis in this region.     

Rho kinases regulate endothelial invasion and migration during valvuloseptal endocardial cushion tissue formation.

Rho-associated kinase (ROCK) is a downstream effector of small Rho-GTPases, and phosphorylates several substrates to regulate cell functions, including actin cytoskeletal reorganization and cellular motility. Endothelial-mesenchymal transformation (EMT) is a critical event in the formation of valves and septa during cardiogenesis. It has been reported that ROCK plays an important role in the regulation of endocardial cell differentiation and migration during mouse cardiogenesis (Zhao and Rivkees [2004] Dev. Biol. 275:183-191). Immunohistochemistry showed that, during chick cardiogenesis, ROCK1 and -2 were expressed in the transforming and migrating endothelial/mesenchymal cells in the outflow tract (OT) and atrioventricular (AV) canal regions from which valvuloseptal endocardial cushion tissue would later develop. Treatment with Y27632, a specific ROCK inhibitor, of cultured AV explants or AV endothelial monolayers of stage 14-minus heart (preactivated stage for EMT) on three-dimensional collagen gel perturbed the seeding of mesenchymal cells into the gel lattice. In these experiments, Y27632 did not suppress the expression of an early transformation marker, smooth muscle alpha-actin. Moreover, Y27632 inhibited the mesenchymal invasion in stage 14-18 AV explants, in which endothelial cells had committed to undergo EMT. ML-9, a myosin light chain kinase inhibitor, also inhibited the mesenchymal invasion in cultured AV explants. These results suggest that ROCKs have a critical role in the mesenchymal cell invasion/migration that occurs at the late onset of EMT.     

Responsiveness of the ANP providing system to volume load in conscious dogs

We examined in detail changes in arterial plasma ANP concentration in response to volume load in conscious dogs. In a 5-min volume load experiment, 18 ml/kg of isosmotic and isooncotic 3% Dextran 40 in saline was infused over a period of 5 min. Mean left atrial pressure (MLAP) increased transiently by 7.6±0.9 mm Hg. Plasma ANP level (P-ANP) did not significantly increase. Assayed P-ANP levels were corrected for hemodilution. Corrected P-ANP (C-ANP) significantly increased from 206±17 to 348±34 pg/ml. However, the level of C-ANP did not reach a steady state. No significant linear correlation was found between increases in MLAP and normalized C-ANP. In a 45-min volume load experiment, the elevated level of MLAP caused by the 5-min volume load was maintained for 40 min by supplemental infusion. C-ANP significantly increased from 196±18 pg/ml to 435±73 ng/ml. The level of C-ANP reached a steady state. A close linear correlation was observed between increases in MLAP and normalized C-ANP. However, the peak time of C-ANP lagged 10 min behind MLAP. These results indicate that it takes 10 min for P-ANP to reach a steady state in fully responding to a volume load, and that the long-term volume load is a prerequisite to the response of the ANP providing system.