Micro-computed tomography and histology to explore internal morphology in decapod larvae

Abstract

Traditionally, the internal morphology of crustacean larvae has been studied using destructive techniques such as dissection and microscopy. The present study combines advances in micro-computed tomography (micro-CT) and histology to study the internal morphology of decapod larvae, using the common spider crab (Maja brachydactyla Balss, 1922) as a model and resolving the individual limitations of these techniques. The synergy of micro-CT and histology allows the organs to be easily identified, revealing simultaneously the gross morphology (shape, size, and location) and histological organization (tissue arrangement and cell identification). Micro-CT shows mainly the exoskeleton, musculature, digestive and nervous systems, and secondarily the circulatory and respiratory systems, while histology distinguishes several cell types and confirms the organ identity. Micro-CT resolves a discrepancy in the literature regarding the nervous system of crab larvae. The major changes occur in the metamorphosis to the megalopa stage, specifically the formation of the gastric mill, the shortening of the abdominal nerve cord, the curving of the abdomen beneath the cephalothorax, and the development of functional pereiopods, pleopods, and lamellate gills. The combination of micro-CT and histology provides better results than either one alone.

Morphology and ultrastructure of the midgut gland ("hepatopancreas") during ontogeny in the common spider crab Maja brachydactyla Balss, 1922 (Brachyura, Majidae)

“…In both cases, the emergence of new tubules can be explained if the MGl contains basal cells; i.e., a cell type that remains dormant in the tubule walls, which when stimulated by physiological processes differentiates into E-cells that will form a new tubule from the walls of an existing tubule. In addition, at the ultrastructural level, M-cells share numerous similarities with the basal cells of the midgut tract and midgut caeca of M. brachydactyla such as small size, rounded shape, and cytoplasm poor in organelles (Castejón et al, 2018), and with the basal cells of the midgut tract and midgut caeca of other decapods (Pugh, 1962;Komuro and Yamamoto, 1968).…”

“…This study investigated the gross morphology and ultrastructure of the midgut gland of a brachyuran species at various stages of development. Micro-CT is a reliable technique for studying the anatomy of crustacean larvae because it reveals the threedimensional morphology of the internal anatomy, including the MGl and other organs (Castejón et al, 2018;Spitzner et al, 2018). In the larval stages, the gross morphology of the MGl of M. brachydactyla comprises14 blind-end tubules.…”

Functional cytology of the hepatopancreas of decapod crustaceans

“…The hepatopancreass originates from the midgut anlage near its junction with the stomach (Figure a,b). The morphogenesis of the hepatopancreas has been described for species from various higher taxa including the penaeid shrimps Penaeus setiferus (Linnaeus, 1767) (Lovett & Felder, ), Penaeus vannamei Boone, 1931 (Muhammad, Zhang, Shao, Dong, & Muhammad, ), and Ploeticus muelleri (Spence Bate, 1888) (Díaz, Fernandez Gimenez, Velurtas, & Fenucci, ), the caridean shrimp Lysmata amboinensis (de Man, 1888) (Tziouveli, Bastos‐Gomez, & Bellwood, ), the lobster Homarus americanus H. Milne Edwards, 1837 (Biesiot & McDowell, ; Factor, ), the spiny lobsters Palinurus ornatus (Fabricius, 1798) (Smith et al, ) and Jasus edwardsii (Hutton, 1875) (Nishida, Takahashi, & Kittaka, ) and the brachyuran crabs Carcinus maenas (Linnaeus, 1758) (Spitzner et al, ), Paralithodes camtschaticus (Tilesius, 1815) (Abrunhosa & Kittaka, ), and Maja brachydactyla Balss, 1922 (Castejón et al, ).…”

“…Paraffin section, H&E‐staining. Scale bar: 200 μm (from Castejón et al, ). (c) Whole mount of phyllosom 3 larva of slipper lobster Palinurus ornatus showing ramification of hepatopancreas tubules (arrowheads) from hepatopancreas lobe (HL).…”

Bioinspired Hydrogel Coating Based on Methacryloyl Gelatin Bioactivates Polypropylene Meshes for Abdominal Wall Repair

“…As a non-destructive technique, micro-CT is usually used to provide specific architectural information on biological materials or synthetic scaffolds [ 35 ]. Micro-CT was also employed by other research groups to evaluate the efficiency of the mineralization process on the polymeric coatings [ 36 , 37 ], but as far as the authors of this study are aware, this technique has never been used to image a thin layer of natural protein coating on a synthetic polymer, probably due to the difficulties of separating two materials with similar X-ray absorbance [ 38 ]. Here, we elaborated a protocol which allowed the visualization of the natural polymer coating on the PP mesh, using a staining agent frequently used in histology—silver nitrate.…”