Ultrastructural Analysis of the Pleopod Tegumental Glands in Male and Female Lobsters, Homarus americanus

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Abstract
We have examined the ultrastructure of the glands in pleopods of mature male and of juvenile and sexually mature female lobsters. Glands are present in both sexes but are most abundant in sexually mature females with well-developed ovaries. The glands are comprised of three cell types (secretory cells, a central cell, and a canal cell) which are arranged in rosettes. There are two types of secretory cells: one produces homogeneous granules and the other honeycombed granules. The central cell has peripheral and central lobes; the central lobes interdigitate with narrow apical projections on the secretory cells. The canal cell possesses a thin ductule which opens into the lumen of the gland and appears to convey secretory material from the lumen to the surface of the pleopod cuticle. Scanning electron micrographs of the pleopod surface reveal that exudate is usually present in the ductule openings; this suggests that the glands secrete continually. Because of their ultrastructural features, we propose that these glands be referred to as "pleopod tegumental glands." Our data suggest that the pleopod tegumental glands have have functions beyond attachment of fertilized eggs to the ovigerous setae.