QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online February 15, 2008
Journal of Experimental Biology 211, 780-789 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.014043

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Insausti, T. C. Articles by Casas, J. Search for Related Content PubMed PubMed Citation Articles by Insausti, T. C. Articles by Casas, J.

The functional morphology of color changing in a spider: development of ommochrome pigment granules

Teresita C. Insausti^* and Jérôme Casas

Université de Tours, Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 6035, Av. Monge, Parc Grandmont, 37200 Tours, France

View larger version (238K): [in this window] [in a new window]   Fig. 1. (A) White Misumena vatia with red stripes (bar, 2 mm). (B) Electron micrograph of the peripheral guanocytes (G) with guanine crystals. Bar, 5 µm. (C) Light micrograph of stained section across the dorsal tegument of the opisthosoma (boxed in A) showing the cuticle (C) with the folded external surface, the epidermis (E) with granules (arrow), the guanocytes (G) and the intestinal diverticula (ID). Bar, 20 µm. (D) Schematic drawing of sections across the dorsal tegument of the opisthosoma, based upon the light microscopic observations. E, epidermis; En, endocuticle; Ep, epicuticle; Ex, exocuticle; H, hemocyte; HS, hypodermic hemolymph sinus, M, muscle; N, nucleus; IT, interstitial tissue, G, guanocyte; ID, intestinal diverticula.

View larger version (141K): [in this window] [in a new window]   Fig. 2. Electron micrographs of the dorsal white tegument of the opisthosoma (boxed in Fig. 1A). (A) Epidermal cells with type I granules (arrow). Electron-lucent areas (holes) are present because granules are sometimes broken up by the microtome cutting. Bar, 2 µm. (B) Detail of type I granules (bar, 0.5 µm). The inset shows a detail of the abundant glycogen rosettes in the epidermal cell cytoplasm (arrow) (bar, 0.5 µm). (C) Detail of the structure of rough endoplasmic reticulum (RER) organized into several concentric rings. Note the presence of large number of mitochondria (arrows) related to these structures. Bar, 0.5 µm. (D) Another detail showing the RER structure in close association with granules (arrow). N, nucleus. Bar, 0.5 µm.

View larger version (121K): [in this window] [in a new window]   Fig. 3. Sections of the opaque-white region of the prosoma of a white spider. (A) Unstained section showing the granules filling the epidermal cells (bar, 30 µm). (B) Same region of tegument as in A, observed under UV light. The granules are strongly autofluorescent (bar, 10 µm). (C) Same region as A and B, observed through a linear polarizer. Numerous granules appear as brilliant (birefringent) against the dark background (bar, 20 µm). (D) Electron micrograph of the epidermal cells of the same region, showing the granules full of microcrystal inclusions (arrow) (bar, 1 µm). C, cuticle; E, epidermis; N, nucleus.

View larger version (102K): [in this window] [in a new window]   Fig. 4. Yellow M. vatia.

View larger version (91K): [in this window] [in a new window]   Fig. 5. Micrographs of cross sections of the tegument of the yellow spider. (A) Unstained section of the light-yellow spider, showing the presence of two types of granules: type II (short, thick arrow) and type III (long, thin arrow) (bar, 10 µm). (B) Same region as in A observed under UV light. The arrow indicates the fluorescent type II granules. Note the absence of fluorescence stemming from the isolated type III granules (bar, 10 µm). (C) Electron micrograph of the same region as A and B showing in detail the granules type II and type III (ommochromes) (bar, 2 µm). The inset shows a detail of a Golgi body (arrow) (bar, 0.5 µm). (D) Unstained section of the bright-yellow spider, with the epidermal cells full of type III granules (arrow) (bar, 20 µm). (E) Electron micrograph of the same region as D. Note the high concentration of the homogeneous granules type III (arrow) filling the cell (bar, 10 µm). The inset shows a detail of the type III granules (bar, 1 µm). (F) Detail of the epidermal cell cytoplasm showing the abundance of glycogen rosettes (asterisks) and a Golgi region (arrow) (bar, 0.5 µm). C, cuticle; E, epidermal cell layer; N, nucleus; Gr II, granule type II; Gr III, granule type III.

View larger version (105K): [in this window] [in a new window]   Fig. 6. Sections of the opaque-white region of the prosoma of the yellow spider. (A) Unstained section showing the distribution of the yellow type III granules (arrow) over the granules with microcrystal inclusions (bar, 50 µm). (B) Same region of tegument as in A observed under UV light, showing the autoflorescence of the granules with microcrystal inclusions (bar, 50 µm). (C) Same region as A and B, observed through a linear polarizer. The granules with microcrystal inclusions were birefringent whereas the type III granules (ommochromes) remained dark (arrows) (bar, 50 µm). (D) Electron micrograph of the epidermal cells of the same region, showing the granules full of inclusions of microcrystals (bar, 5 µm). (E) Detail of D showing a structure of accumulation of microcrystals (arrow) (bar, 1 µm). C, cuticle; E, epidermis.

View larger version (101K): [in this window] [in a new window]   Fig. 7. Micrographs of cross sections of the red stripe zone. (A–C) White spider. (A) Unstained section. The red zone (left) and the white zone (right) of the epidermis. Two types of granules in the red zone are shown: the basal red type III (ommochromes) (asterisk) and type I granules (short, thick arrow) in the apical region of the cell. Only type I granules (long, thin arrow) are present in the white zone (bar, 20 µm). (B) Section of the red stripe zone showing fluorescent type I granules (arrow) in the apical and medial region of the epidermis. Note the absence of fluorescence from nuclei and the type III granules (basal region of the epidermis) (bar, 20 µm). (C) Electron micrograph of the red stripe showing a detail of the distribution of the type I and type III granules (bar, 2 µm). (D,E,F) Yellow spider. (D) The red zone (left; arrow) and the yellow zone (right) of the epidermis. Only type III granules (red and yellow) were observed in the red zone (bar, 20 µm). (E) Same region as in D, observed under UV light. Only the type II granules of the yellow zone show autofluorescence (arrow, half right of the picture) (bar, 20 µm). (F) Electron micrograph showing a detail of the same region as D and E. The dotted line delimits the red stripe and yellow regions (bar, 2 µm). C, cuticle; Gr I, granule type I; Gr III, granule type III.

View larger version (19K): [in this window] [in a new window]   Fig. 8. Development of progranules (types I and II) into pigment granules of ommochromes (type III). Ommochromes are progressively deposited onto a homogeneous matrix of type I progranules (white spider), through an intermediate state of vesiculated progranules type II (light yellow spider). The progranules then decrease slightly in size and form the ommochrome pigment granules (type III) (bright yellow spider).