. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 300 M. K. MONTGOMERY AND M. McFALL-NGAI vjmr i>\'-'- ftl. Figure 4. Transmission electron micrograph of the light organ of a juvenile 24 h post-hatch. The crypts, populated with bacterial symbionts. are lined with a simple cuboidal epithelium whose apical surface bears an extensive brush border of microvilli. This epithelial cell layer is surrounded by a layer ot blood vessels and connective tissue. The reflector is composed of several layers of electron-dense platelets, and is immediately adjacent to the ink sac whose in
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 300 M. K. MONTGOMERY AND M. McFALL-NGAI vjmr i>\'-'- ftl. Figure 4. Transmission electron micrograph of the light organ of a juvenile 24 h post-hatch. The crypts, populated with bacterial symbionts. are lined with a simple cuboidal epithelium whose apical surface bears an extensive brush border of microvilli. This epithelial cell layer is surrounded by a layer ot blood vessels and connective tissue. The reflector is composed of several layers of electron-dense platelets, and is immediately adjacent to the ink sac whose inner surface is composed of a simple squamous epithelium. Scale bar = 10 jim. (bet, bacteria; is. ink sac; n, nucleus of epithelial cell; r, reflector). based on measurements of live specimens with a com- pound microscope. (Tissue shrinkage with SEM is 25- 30% in the linear dimension.) TEM revealed that the ap- pendages and surrounding ciliated surface are formed from cells of the surface epithelium, each cell possessing numerous cilia averaging 20 /urn in length and 300 nm in width. Each cilium is surrounded by several microvilli 1- 2 nm in length and 70-115 nm in width, whereas micro- villi on adjacent non-ciliated surface epithelium were considerably shorter, ranging from to ^m in length. On the surface of the light organ are several pores (3 on each side), ranging from 5 to 15 ^m in diameter, that lead into the interior of the organ (Fig. IB). Three-dimensional reconstruction of the light organ of a newly hatched juvenile revealed that each pore leads into a separate epithelium-lined cavity or crypt (Fig. 2A); these pores, present on the ventral surface of the organ near the base of the epithelial appendages, connect the crypts to the mantle cavity. The three pairs of crypts, which are roughly bilaterally symmetrical, are different in size. On each side of the incipient light organ the smallest crypt is located most anterior, the medium-sized crypt is most posterior,
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
