Angiostrongylus costaricensis and Experimental Infection of Sarasinula marginata II. Elimination Routes

Angiostrongylus costaricensis   intermediate hosts are terrestrial mollusks mostly belonging to the Veronicellidae family. In the present investigation we focused on the mechanisms of larval expulsion from Sarasinula marginata infected with A. costaricensis. Twenty-five mollusks were individually infected with 5000 L1 and sacrificed at 30 min and 1, 2, 4, 6, and 8 h post-infection and at days 1, 2, 4, 5, 6, 8, 10, 11, 12, 14, 15, 16, 20, 21, 22, 25, 26, 28, and 30 post-infection; the mollusks were then fixed and stained. Diverse organs involved throughout the course of the migratory routes of larvae from oral penetration on were specified and the mechanisms of larval access to the fibromuscular layer through the kidney, rectum, and vascular system were defined. The elimination of L3, derived from oral and/or cutaneous infections, appears to depend on granulomas located close to the excretory ducts of mucous cells

Penetration Sites and Migratory Routes of Angiostrongylus costaricensis in the Experimental Intermediate Host (Sarasinula marginata)

The intermediate hosts of Angiostrongylus costaricensis are terrestrian molluscs, mostly of the family Veronicellidae. The present work aimed at clarifying more accurately the sites of penetration and the migratory routes of A. costaricensis in the tissue slugs and at verifying the pattern of the perilarval reaction at different times of infection. Slugs were individually infected with 5,000 L1, and killed from 30 min to 30 days after infection. From 30 min up to 2 hr after infection, L1 were found within the lumen of different segments of the digestive tube having their number diminished in more advanced times after exposition until complete disappearance. After 30 min of exposition, percutaneous infection occurred, simultaneously to oral infection. Perilarval reaction was observed from 2 hr of infection around larvae in fibromuscular layer, appearing later (after 6 hr) around larvae located in the viscera. A pre-granulomatous reaction was characterized by gradative concentration of amebocytes around larvae, evolving two well-organized granulomas. In this work we confirmed the simultaneous occurrence of oral and percutaneous infections. Perilarval reaction, when very well developed, defined typical granulomatous structure, including epithelioid cell transformation. The infection also caused a systemic mobilization of amebocytes and provoked amebocyte-endothelium interactions

Angiostrongylus costaricensis and experimental infection of Sarasinula marginata II: elimination routes

Angiostrongylus costaricensis intermediate hosts are terrestrial mollusks mostly belonging to the Veronicellidae family. In the present investigation we focused on the mechanisms of larval expulsion from Sarasinula marginata infected with A. costaricensis. Twenty-five mollusks were individually infected with 5000 L1 and sacrificed at 30 min and 1, 2, 4, 6, and 8 h post-infection and at days 1, 2, 4, 5, 6, 8, 10, 11, 12, 14, 15, 16, 20, 21, 22, 25, 26, 28, and 30 post-infection; the mollusks were then fixed and stained. Diverse organs involved throughout the course of the migratory routes of larvae from oral penetration on were specified and the mechanisms of larval access to the fibromuscular layer through the kidney, rectum, and vascular system were defined. The elimination of L3, derived from oral and/or cutaneous infections, appears to depend on granulomas located close to the excretory ducts of mucous cells

Histological Analyses Demonstrate the Temporary Contribution of Yolk Sac, Liver, and Bone Marrow to Hematopoiesis during Chicken Development

<div><p>The use of avian animal models has contributed to the understanding of many aspects of the ontogeny of the hematopoietic system in vertebrates. However, specific events that occur in the model itself are still unclear. There is a lack of consensus, among previous studies, about which is the intermediate site responsible for expansion and differentiation of hematopoietic cells, and the liver's contribution to the development of this system. Here we aimed to evaluate the presence of hematopoiesis in the yolk sac and liver in chickens, from the stages of intra-aortic clusters in the aorta-genital ridges-mesonephros (AGM) region until hatching, and how it relates to the establishment of the bone marrow. <i>Gallus gallus domesticus</i> L. embryos and their respective yolk sacs at embryonic day 3 (E3) and up to E21 were collected and processed according to standard histological techniques for paraffin embedding. The slides were stained with hematoxylin-eosin, Lennert's Giemsa, and Sirius Red at pH 10.2, and investigated by light microscopy. This study demonstrated that the yolk sac was a unique hematopoietic site between E4 and E12. Hematopoiesis occurred in the yolk sac and bone marrow between E13 and E20. The liver showed granulocytic differentiation in the connective tissue of portal spaces at E15 and onwards. The yolk sac showed expansion of erythrocytic and granulocytic lineages from E6 to E19, and E7 to E20, respectively. The results suggest that the yolk sac is the major intermediate erythropoietic and granulopoietic site where expansion and differentiation occur during chicken development. The hepatic hematopoiesis is restricted to the portal spaces and represented by the granulocytic lineage.</p></div

Chicken liver development without hematopoietic activity from E9 to E 14.

<p>The embryonic day (E) is indicated in the upper right corner in each picture. Hp, hepatoblasts; CV, central vein; sinusoidal capillaries (asterisks); PV, portal vein; CT, connective tissue. (<b>A</b>) Lennert's Giemsa and (<b>B</b>–<b>F</b>) Hematoxylin-eosin stains. Bars 20 µm.</p

Scheme of hematopoiesis in the yolk sac, liver, and bone marrow during chicken development.

<p>Bars indicate the temporal distribution of this activity in the AGM region, yolk sac (YS), liver (L), and bone marrow (BM). Black dotted lines indicate the presence of both erythropoiesis and granulopoiesis in the YS (<b>C</b>–<b>F</b>) and BM (<b>E</b>–<b>G</b>). The blue dotted line is to draw attention to the granulopoiesis in the L. (<b>A</b>) At E4, immature erythropoietic cells, incomplete erythropoietic foci, and rare granulocytes are distributed in the YS. (<b>B</b>) From E6, the YS shows complete erythropoietic foci (all maturation stages are seen) and some granulocytes. (<b>C</b>) From E7, complete erythropoietic and granulopoietic foci are distributed in the YS. (<b>D</b>) At E10, erythropoietic and granulopoietic foci are seen in the YS. Granulocytes at different stages of maturation are noted in the BM. At E11, basophilic cells are also seen in the BM. (<b>E</b>) At E15, both erythropoietic and granulopoietic foci are frequently observed in the YS and BM. In this phase, granulopoiesis begins in the L around the portal vessels. (<b>F</b>) At E17, hematopoiesis is reduced in the YS. Granulopoiesis persists in the L portal spaces, and both erythropoietic and granulopoietic activities are noted in the BM. (<b>G</b>) At E21, granulopoietic foci are seen in L connective tissues, both erythrocytic and granulocytic activities are observed in the BM, and the YS is no longer a hematopoietic site.</p

Chicken liver development without hematopoietic activity from E3 to E8.

<p>The embryonic day (E) is indicated in the upper right corner in each picture. (<b>A</b>, <b>C</b>, <b>D</b>) Numerous mitosis (arrows) are seen in hepatoblasts (Hp). (<b>B</b>) Mitosis in circulating erythrocyte (arrow). (<b>E</b>) Immature hematopoietic circulating cells (arrows) in sinusoidal capillaries (vessels located between hepatoblast cords, Hp). Note the large and irregular lumen of the sinusoidal capillaries. (<b>F</b>) Foci of immature erythropoietic cells in circulation (limited by arrows). Hp, hepatoblasts; VD, venous duct; sinusoidal capillaries (asterisks). (<b>A</b>, <b>C</b>, <b>F</b>) Hematoxylin-eosin and (<b>B</b>, <b>D</b>, <b>E</b>) Lennert's Giemsa stains. Bars 20 µm.</p

(A–K) Erythropoiesis (Ery) and (E–L) granulopoiesis (Gr) in chicken yolk sac between E3 and E20.

<p>The embryonic day (E) is indicated in the upper right corner in each picture. Thin arrows show mitosis in erythrocytes (<b>A</b>, <b>D</b>, <b>E</b>, <b>I</b>, <b>K</b>) and in a granulocyte (<b>H</b>). (<b>A</b>) Predominance of basophilic cells with a slight acidophily. (<b>B</b>, <b>C</b>) Numerous pro-erythroblasts and basophilic erythroblasts (Ery) between artery (Art) and endoderm (End). (<b>C</b>) Note a cell band leukocyte (arrowhead). (<b>D</b>) Erythrocytic (Ery) focus showing mature erythrocyte (arrowhead). (<b>F</b>, <b>G</b>) Cell band leukocyte (arrowhead). (<b>H</b>) Eosinophil granules into granulocytic cells at different stages of maturation show the cytoplasm of these cells in red-orange color. (<b>I</b>) Promyelocyte (arrowhead). (<b>J</b>, <b>K</b>) Foci of erythrocytic (white asterisks) and granulocytic (black asterisks) differentiation are present in equivalent numbers at this stage. (<b>K</b>) Mature leukocyte (arrowhead). (<b>L</b>) Myelocyte (arrowhead). (<b>E</b>–<b>K</b>) Note that granulocytic and erythrocytic lineages do not mix. End, endoderm; Art, artery. (<b>A</b>–<b>E</b>, <b>G</b>, <b>I</b>, <b>L</b>) Lennert's Giemsa, (<b>F</b>, <b>J</b>, <b>K</b>) Hematoxylin-eosin, and (<b>H</b>) Sirius Red stains at pH 10.2. Bars 20 µm.</p

(A–H) Panoramic view of chicken yolk sacs between E3 and E19.

<p>The embryonic day (E) is indicated in the upper right corner in each picture. Histological sections of yolk sacs show endoderm (End), vessels (Art), and areas of hematopoietic foci (arrows). (<b>A</b>–<b>E</b>) The areas occupied by these foci are shown gradually increasing in the photomicrographs between E3 and E12, and (<b>F</b>–<b>H</b>) decreasing in onwards stages. (<b>G, H</b>) Atrophic vessels (arrowheads). (<b>F</b>–<b>H</b>) Yolk (Y). Hematoxylin-eosin. Bars 100 µm.</p