{"id":5211,"date":"2021-05-12T22:41:22","date_gmt":"2021-05-12T20:41:22","guid":{"rendered":"https:\/\/meddists.com\/learn\/clinical\/hematology\/hematopoiesis-ontogenesis-and-reticulocyte-counting\/"},"modified":"2021-05-22T16:07:11","modified_gmt":"2021-05-22T14:07:11","slug":"hematopoiesis-ontogenesis-and-reticulocyte-counting","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/clinical\/internal-medicine\/hematology\/hematopoiesis-ontogenesis-and-reticulocyte-counting\/","title":{"rendered":"Hematopoiesis, ontogenesis and reticulocyte counting"},"content":{"rendered":"<span class=\"block-heading\" id=\"header_1\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Embryology (ontogenesis)<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_1\">\n\n\n<p class=\"wp-block-paragraph\">Early embryogenesis begins in the yolk sac. Definitive hematopoietic cells are derived from stem cells in the AGM (aorto-gonado-mesonephros) region, populating the liver and spleen and eventually migrating to the bone marrow.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Yolk sac: appear by day 10, continues up to 2 months (hemocytoblasts)<\/li><li>Liver and spleen: appear by week 5, overlap with the yolk sac, continue up to 7 months<\/li><li>Bone-marrow: appear by week 11, overlap with the liver and spleen, most important from 6 months<\/li><li>The liver and spleen can continue until 2 weeks after birth<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Before childhood, all bone marrow is hemopoietic; after childhood, only the central skeleton and proximal femur and humerus remain hematopoietic (&#8220;red-marrow&#8221;), while the rest is replaced with adipose tissue (&#8220;yellow-marrow&#8221;).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In the setting of severe or prolonged blood-loss, yellow marrow can transform back to red marrow.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_2\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Hematopoiesis<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_2\">\n\n\n<ul class=\"wp-block-list\"><li>Starts with a pluripotent stem cell, CD34 positive.<\/li><li>They differentiate into hemopoietic progenitor cells (myeloid and lymphoid).<\/li><li>Myeloid linage gives rise to RBCs, granulocytes (neutrophils, eosinophils, basophils), monocytes, platelets.<\/li><li>Lymphoid lineage gives rise to B and T lymphocytes and NK cells.<\/li><li>Stem cells are able to move around the body and can be found in the blood in low numbers.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_3\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Hemoglobin<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_3\">\n\n\n<p class=\"wp-block-paragraph\">Hemoglobin consists of heme (<em>iron <\/em>+ <em>protoporphyrin<\/em>) + globin.<\/p>\n\n\n\n<ul class=\"wp-block-list\" id=\"block-dc58ba66-243a-4939-9842-30e92061b6c3\"><li><strong>Primitive hemopoiesis<\/strong>: 2 pairs of zetta-epsilon (Hb-Gower1) or alpha-epsilon (Hb-Gower2) or zetta-gamma (Hb-Portland)<\/li><li><strong>Fetal<\/strong>: 2 pairs of alpha-gamma (HbF)<\/li><li><strong>Adult<\/strong>: 2 pairs of alpha-beta (HbA) or the much less common alpha-delta (HbA2)<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Z G<br>Z E<br>A E<br>A G<br>A B<br>A D<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"529\" src=\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/05\/oxygen-hemoglobin-1024x529.png\" alt=\"\" class=\"wp-image-5432\" srcset=\"https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/05\/oxygen-hemoglobin-1024x529.png 1024w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/05\/oxygen-hemoglobin-300x155.png 300w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/05\/oxygen-hemoglobin-768x397.png 768w, https:\/\/meddists.com\/learn\/wp-content\/uploads\/2021\/05\/oxygen-hemoglobin.png 1043w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption><strong>Figure 1.<\/strong> Hgb-O2 affinity<\/figcaption><\/figure>\n\n\n<\/span><span class=\"block-heading\" id=\"header_4\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Pathologies<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_4\">\n\n\n<ul class=\"wp-block-list\"><li>Left-shift (higher affinity) in thalassemias<\/li><li>Right-shift (lower affinity) in sickle-cell disease<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_5\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Reticulocyte counting<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_5\">\n\n\n<p class=\"wp-block-paragraph\">Reticulocytes are immature RBCs. They stay in peripheral blood for up to 1 day. They have no nucleus but they do have scattered RNA inside their cytoplasm. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Reticulocyte count refers to a procedure in which the number of reticulocytes is counted from peripheral blood. It reflects the erythropoietic activity of the bone marrow.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Reticulocyte analysis includes measurements of mRNA content and the maturity of reticulocytes, cell volume, hemoglobin concentration, and content. <\/li><li>The reticulocyte hemoglobin content provides an indirect measure of the functional iron available for new red blood cell production over the previous 3-4 days. <\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_6\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Results<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_6\">\n\n\n<p class=\"wp-block-paragraph\">The normal values are between <strong>0.5-2.5%<\/strong> (up to 6% in the newborn), or 50\u2013150G\/L.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Elevated RC is seen in hemolysis and blood loss.<\/li><li>Decreased RC is seen in:<ol><li>Aplastic anemia<\/li><li>Exposure to irradiation and chemotherapy<\/li><li>Chronic infections<\/li><\/ol><\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_7\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Methods<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_7\">\n\n\n<ul class=\"wp-block-list\"><li>In the past, the reticulocytes were counted in a microscopic slide; nowadays we use automated flow cytometry.<\/li><li>To demonstrate reticulocytes, stain and incubate the sample (a procedure known as <em>supra-vital staining<\/em>); reticulocytes take up the stain, showing the RNA as dark inclusions.<ul><li>The staining used is typically <em>new methylene blue<\/em>, <em>Brilliant Cresyl Blue<\/em>, or <em>Pure azure B<\/em>.<\/li><li>Smears of the mixture are prepared and examined under a microscope by counting the number of reticulocytes per 1000 red blood cells.<\/li><\/ul><\/li><\/ul>\n<\/span><div id=\"the_titles\" style=\"display:none;\"><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Embryology (ontogenesis)<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Hematopoiesis<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Hemoglobin<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Pathologies<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Reticulocyte counting<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Results<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Methods<\/h4><\/div>","protected":false},"excerpt":{"rendered":"<p>Embryology (ontogenesis) Early embryogenesis begins in the yolk sac. Definitive hematopoietic cells are derived from stem cells in the AGM (aorto-gonado-mesonephros) region, populating the liver and spleen and eventually migrating to the bone marrow. Yolk sac: appear by day 10, continues up to 2 months (hemocytoblasts) Liver and spleen: appear by week 5, overlap with [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":4472,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-5211","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.9 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Hematopoiesis, ontogenesis and reticulocyte counting &#8211; Meddists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/meddists.com\/learn\/clinical\/internal-medicine\/hematology\/hematopoiesis-ontogenesis-and-reticulocyte-counting\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/\",\"name\":\"Hematopoiesis, ontogenesis and reticulocyte counting &#8211; Meddists\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/meddists.com\\\/learn\\\/wp-content\\\/uploads\\\/2021\\\/05\\\/oxygen-hemoglobin-1024x529.png\",\"datePublished\":\"2021-05-12T20:41:22+00:00\",\"dateModified\":\"2021-05-22T14:07:11+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/hematopoiesis-ontogenesis-and-reticulocyte-counting\\\/#primaryimage\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/wp-content\\\/uploads\\\/2021\\\/05\\\/oxygen-hemoglobin.png\",\"contentUrl\":\"https:\\\/\\\/meddists.com\\\/learn\\\/wp-content\\\/uploads\\\/2021\\\/05\\\/oxygen-hemoglobin.png\",\"width\":1043,\"height\":539,\"caption\":\"Figure 1. 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