Expression of HNK1 epitope by the cardiomyocytes of the early embryonic chick: In situ and in vitro studies

Monoclonal antibody HNK1 reacts with a carbohydrate epitope in cell surface glycoproteins and glycolipids. During development, in various species the HNK1 epitopes are expressed in migrating neural crest cells and in the developing conduction cardiomyocytes. The conduction system is generally thought to be developed from cardiomyocytes, but some investigators have hypothesized that it is derived from the neural crest because conduction myocytes express neural antigens, including HNK1. Using immunohistochemistry, we examined the spatiotemporal expression of HNK1 in early chick cardiogenesis (stages 4 to 18) and whether cultured precardiac mesoderm does or does not express HNK1 as well as sarcomeric myosin (MF20). HNK1 was first expressed in the premyocardium at stage 8. At stage 10, HNK1‐positive cardiomyocytes were scattered along the straight heart tube. By stage 18, HNK1‐positive cardiomyocytes had become restricted to the atrium and sinus venosus. Atrioventricular cushion mesenchyme also expressed an HNK1 epitope. Immunostaining of HNK1 and MF20 in cultured precardiac mesoderm showed that there are at least three types of cells: 1) cardiomyocytes without HNK1 expression, 2) cells possessing both HNK1‐ and MF20‐immunoreactivity, and 3) mesenchymal cells with HNK1. Immunogold electron microscopy showed that cardiomyocytes containing sparsely distributed myofibrils associated with the Z‐band react with anti‐HNK1 antibody. Our observations showed a direct evidence for the first time that the precardiac mesoderm generates HNK1‐positive cardiomyocytes with morphological features similar to those of conduction cardiomyocytes. Anat Rec 263:326–333, 2001. © 2001 Wiley‐Liss, Inc.     

Formation of hematopoietic colonies of donor's type in the bone marrow of irradiated chicks after transplantation of quail yolk sac and limb bud cells into their bone marrow

Ability to form hematopoietic cell colonies from the yolk sac and limb bud of a quail embryo at the 60 h incubation stage (i.e., before establishment of a closed circulation) was studied in the bone marrow of sublethally irradiated 3-week-old chicks. The experimental results are based on the ability to distinguish between quail and chick cells by means of a natural marke (Feulgen-positive nucleolus). After transplantation of limb bud cells roughly 3 times more hematopoietic colonies were found to be formed than after transplantation of yolk sac cells of the quail embryo. With the dose of irradiation used, about 75% of exogenous (quail) and 25% of endogenous (chick) hematopoietic colonies were identified in the bone marrow.Department of Histology and Cytology, Moscow University. (Presented by Academician of the Acad of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny Vol. 88, No. 10, pp. 432–434, October, 1979.     

Examining the combinatorial model of motor neuron survival by expression profiling of trophic factors and their receptors in the embryonic Gallus gallus

During embryogenesis, limb‐innervating lateral motor column (LMC) spinal motor neurons (MN) are generated in excess and subsequently nearly half of them die. Many motor neuron survival factors (MnSFs) have been shown to suppress this default programmed cell death (PCD) program through their receptors (MnSFRs), raising the possibility that they are involved in matching specific MNs with their target muscles. Published observations suggest a combinatorial model of MnSF/Rs function, which assumes that during the PCD phase, MNs are expressing combinations of MnSFRs, whereas the limb muscles innervated by these MNs express cognate combinations of MnSFs. We tested this model by expression profiling of MnSFs and their receptors in the avian lumbosacral spinal cord and limb muscles during the peak PCD period. Our findings highlight the complexity of MnSF/Rs function in the control of LMC motor neuron survival. Developmental Dynamics 239:965–979, 2010. © 2010 Wiley‐Liss, Inc.     

Phenotypical changes of embryonic chick adrenal medullary cells in vitro induced by nerve growth factor and ciliary neuronotrophic factor

This study investigates the survival properties and changes in the morphological phenotype of adrenal medullary (chromaffin and neuronal) cells cultured from embryonic chicks at different developmental ages (embryonic days E8 to E16) in response to nerve growth factor (NGF) and ciliary neuronotrophic factor (CNTF). The 4-day survival of medullary cells from all embryonic ages except E8 was about 80% of the seeded cells and was only slightly enhanced by the addition of saturating doses of CNTF (10 ng/ml). With no factors, after 4 days 10-30% of the surviving medullary cells extended neurites. NGF (100 ng/ml) and, even more, CNTF (10 ng/ml) and their combination substantially increased the proportions of neurite-bearing cells (up to 70%). The effect of the factors were maximal at E10 and E12 and declined at older developmental ages. Neurite growth was virtually unaffected by NGF and CNTF at E8. These results show that in vitro survival and neurite growth of chick adrenal medullary cells in response to trophic factors is developmentally regulated.