Digestive system of <i>Neocaridina heteropoda</i> with the midgut epithelium.

<p>(A) <i>Neocaridina heteropoda</i>. XMT. Bar = 2 mm. (B-C) A fragment of the digestive system of <i>N</i>. <i>heteropoda</i>. (B) XMT. Bar = 2 mm. (C) Stereomicroscopy. Bar = 272 µm. (D) The beginning of two diverticles of the hepatopancreas (arrows). Light microscopy. Bar = 28 µm. (E) Diagrammatic representation of epithelia in the intestine and zones of hepatopancreas. Intestine (in), hepatopancreas (hp), stomach (white arrow), midgut lumen (l), intestine epithelium (in), basal lamina (arrowhead).</p

Secretion in the midgut epithelium.

<p>(A-B) Apocrine secretion in the intestine. Digestive cells (dc) with distinct evaginations of the apical membrane (arrows). (A) TEM. Bar = 1.7 µm. (B) TEM. Bar = 1.3 µm. (C) Microapocrine secretion: small bulges of microvilli (arrows) of the digestive cells (dc). TEM. Bar = 0.33 µm. Autophagosome (au), midgut lumen (l), microvilli (mv), nucleus (n), cortical layer of the apical cytoplasm (star), smooth septate junction (arrowhead).</p

Changes in the fibrillar (fc) and storage (sc) cells according to their distance from the differentiation region of the tubule in <i>N</i>. <i>heteropoda</i>.

<p>TEM. (A) Bar = 1.7 µm. (B) Bar = 1.14 µm. (C) Bar = 1 µm. (D) Bar = 5.4 µm. (E) Bar = 6.5 µm. (F) Bar = 1.44 µm. (G) Bar = 1.32 µm. Hepatopancreatic lumen (l), microvilli (mv), basal lamina (bl), nucleus (n), reserve material (rm), vacuole (v), mitochondria (m), cisterns of the rough endoplasmic reticulum (RER), Golgi complexes (d), residual bodies (rb).</p

The scanning parameters used during the tests using X-ray microtomography.

<p>The scanning parameters used during the tests using X-ray microtomography.</p

Differentiation region of hepatopancreatic tubules in <i>N</i>. <i>heteropoda</i>.

<p>(A) Cross section through the differentiation region. Light microscopy. Bar = 26 µm. (B) Longitudinal section through the differentiating region of tubule. TEM. Bar = 2.2 µm. (C) Cytoplasm of undifferentiated cells. TEM. Bar = 1.7 µm. (D) A higher magnification of (B). Apical membrane without any folds or microvilli (arrowhead) and distinct smooth septate junctions (arrows) between adjacent cells. TEM. Bar = 0.9 µm. (E) Cytoplasm rich in organelles. Gap junctions (arrows) between adjacent cells. TEM. Bar = 0.7 µm. (F) Sporadic regenerative cells (rc) with cytoplasm that was poor in organelles. TEM. Bar = 1 µm. Undifferentiated cells (uc), hepatopancreatic lumen (l), basal lamina (bl), nucleus (n), cisterns of the rough (RER) and smooth (SER) endoplasmic reticulum, mitochondria (m), Golgi complexes (d).</p

Proximal region of hepatopancreatic tubules in <i>N</i>. <i>heteropoda</i>.

<p>(A) Two types of cells were distinguished in the epithelium of the proximal region in hepatopancreatic tubule: type I—fibrillar cells (fc) and type II—storage cells (sc). TEM. Bar = 1.8 µm. (B) Fibrillar cells (fc) and storage cell (sc). TEM. Bar = 2.7 µm. (C) A higher magnification of (B). Fibrillar cells (fc)—a cortical layer with electron-lucent vesicles (v) and storage cell (sc). TEM. Bar = 1.5 µm. (D) The cytoplasm of fibrillar (fc) and storage (sc) cells. TEM. Bar = 0.7 µm. (E) Gap junctions (arrow) and septate junctions (arrowheads). TEM. Bar = 0.5 µm. (F) Fibrillar cells (fc). Basal membrane with small folds (arrows). TEM. Bar = 2.7 µm. (G) Autophagosomes (au) accumulated above the nucleus (n). TEM. Bar = 1.7 µm. Hepatopancreatic lumen (l), microvilli (mv), nucleus (n), basal lamina (bl), smooth septate junctions (arrows), reserve material (rm), cisterns of the rough (RER) and smooth (SER) endoplasmic reticulum, Golgi complexes (d), mitochondria (m), autophagosome (au).</p

Distal region of hepatopancreatic tubules in <i>N</i>. <i>heteropoda</i>.

<p>(A) Longitudinal section through the distal (arrows) and differentiating (arrowheads) regions of tubule with regenerative cells (rc). Light microscopy. Bar = 26 µm. (B) Cross section through the distal region with regenerative cells (rc). Light microscopy. Bar = 19 µm. (C) Regenerative cells (rc). TEM. Bar = 3.15 µm. (D) Regenerative cells (rc). TEM. Bar = 2.43 µm. (E) Septate junctions (arrow) between regenerative cells. TEM. Bar = 1 µm. Hepatopancreatic lumen (l), visceral muscles (mc), intestine (in), basal lamina (bl), nucleus (n), mitochondria (m), cisterns of the rough endoplasmic reticulum (RER).</p

Histochemical staining of the midgut epithelium of <i>N</i>. <i>heteropoda</i>.

<p>(A) Intestine. PAS. Light microscopy. Bar = 10 µm. (B) Intestine. Sudan Black B. Light microscopy. Bar = 10 µm. (C) Intestine. BPB. Light microscopy. Bar = 12 µm. (D) Hepatopancreas. PAS. Light microscopy. Bar = 19 µm. (E) Hepatopancreas. Sudan Black B. Light microscopy. Bar = 12 µm. (F) Hepatopancreas. BPB. Light microscopy. Bar = 21 µm. Midgut epithelium (e), midgut lumen (l), basal lamina (bl), positive reaction (arrows).</p

Regenerative cells in the intestine of <i>N</i>. <i>heteropoda</i>.

<p>(A-C) Regenerative cells (rc) situated between the basal regions of the digestive cells (dc). (A) Light microscopy. Bar = 12 µm. (B) TEM. Bar = 0.76 µm. (C) The cytoplasm of the regenerative cells (rc) poor in organelles. TEM. Bar = 0.6 µm. (D) Dividing regenerative cell (rc), digestive cell (dc). TEM. Bar = 3 µm. Nucleus (n), basal lamina (bl), mitochondria (m), cisterns of the rough endoplasmic reticulum (RER).</p

Structure and Ultrastructure of the Endodermal Region of the Alimentary Tract in the Freshwater Shrimp <i>Neocaridina heteropoda</i> (Crustacea, Malacostraca)

<div><p>The freshwater shrimp <i>Neocaridina heteropoda</i> (Crustacea, Malacostraca, Decapoda) originates from Asia and is one of the species that is widely available all over the world because it is the most popular shrimp that is bred in aquaria. The structure and the ultrastructure of the midgut have been described using X-ray microtomography, transmission electron microscopy, light and fluorescence microscopes. The endodermal region of the alimentary system in <i>N</i>. <i>heteropoda</i> consists of an intestine and a hepatopancreas. No differences were observed in the structure and ultrastructure of males and females of the shrimp that were examined. The intestine is a tube-shaped organ and the hepatopancreas is composed of two large diverticles that are divided into the blind-end tubules. Hepatopancreatic tubules have three distinct zones – proximal, medial and distal. Among the epithelial cells of the intestine, two types of cells were distinguished – D and E-cells, while three types of cells were observed in the epithelium of the hepatopancreas – F, B and E-cells. Our studies showed that the regionalization in the activity of cells occurs along the length of the hepatopancreatic tubules. The role and ultrastructure of all types of epithelial cells are discussed, with the special emphasis on the function of the E-cells, which are the midgut regenerative cells. Additionally, we present the first report on the existence of an intercellular junction that is connected with the E-cells of Crustacea.</p></div