Ultrastructure of the larval corpus allatum of Hyphantria cunea drury (Insecta, Lepidoptera)

Abstract

The corpora allata of the three last larval instars were studied in newly molted animals, at the beginning, middle, and end of the feeding period, and during the molt period. They were found to consist of uniform gland cells, whose ultrastructure changes in the course of the instars. In glands cells considered to be resting, the outer and inner nuclear membranes run in parallel without forming a dilated perinuclear space. Mitochondria are small, polymorphic, with an electron-dense matrix. The smooth endoplasmic reticulum (SER) appears as stacks of parallel cisternae near the nuclear envelope and in the rest of the cytoplasm, and as accumulations of twisted profiles. Occasionally, the SER takes the form of paracrystalline bodies. There are few small smooth-surfaced vesicles in the cytoplasm. In cells considered as active, a dilated perinuclear space occurs. The peripheral ends of profiles forming the SER are swollen, and numerous vesicles and vacuoles bud off from them to fill the cytoplasm. Mitochondria are large, with a more transparent matrix. The plasma membrane of gland cells located just beneath the connective tissue sheath forms numerous small invaginations. The corpora allata consist of resting cells during the molt periods. At the beginning of each instar, few active gland cells appear. In the middle of the second to last and the third to last instars, the bulk of the gland cells is active. At the end of these instars, there are both active and inactive cells. In the middle of the last instar, the gland cells are inactive or subactive, and at its end, all gland cells are completely inactive.

15. Endocrine glands and hormones

“…In Lepidoptera the major release site for NSM appears to be the CA-CC complex, although earlier studies pointed to CA as the primary release site (Nishiitsutsuji-Uwo, 1961;Mitsuhashi, 1963;Ym & Chippendale, 1979 b Meóla & Meóla, 1983), whereas in another bombycoid, Mimas tiliae (Sphingidae) the CC is the major site of release, and the same applies to Pier is rapae (Papilionoidea-Pieridae), Tyria jacobaeae and Hyphantria cunea (Noctuoidea-Arctiidae) (Highnam, 1958;Kono, 1973; Melnikova & Panov, 1975;Philogène & Massalski, 1976). The CC nerves themselves can be release sites, since many varicose terminal branches have been identified running into the aorta (Copenhaver & Truman, 1986;Ichikawa, 1991).…”

“…A distinguishing feature of active CA cells is the presence of conspicuous tubular, vesicular or stacked smooth endoplasmic reticulum (sER). CA cells of all examined Lepidopteran species except Antheraea pernyi (Bombycoidea-Saturniidae) are characterized by little rough endoplasmic reticulum (rER) and prominent smooth endoplasmic reticulum (sER) (Melnikova & Panov, 1975;Cassier, 1990). Other features include a large nucleus, a large number of mitochondria, vacuoles, and more cytoplasm.…”

“…The growth of cells appears to be related to somatic growth and not to biosynthetic activity (de la Garza et al, 1991). The large number of cells in Manduca CA may be an exception, since CA of other species consist of much smaller number of cells: 25 in Pectinophora gossypiella (Gelechioidea-Gelechiidae) ( Raina & Borg, 1980), 18 in Monema flavescens (Zygaenoidea-Limacodidae) (Takeda, 1977), 25 -35 in Hyphantria cunea (Noctuoidea-Arctiidae) ( Melnikova & Panov, 1975) and [30][31][32][33][34][35] in Papilio demoleus (Papilionoidea-Papilionidae) (Srivastava et al, 1975). In general, the ultra-structural characteristics of CA cells from these various species are similar to those of Manduca CA cells.…”

Effects of starvation and sucrose feeding on corpora allata of last instar larvae of Manduca sexta: in vitro activity, size, and cell number

“…Therefore the increase in CA volume in older larvae and prepupae must be due to increase in cell size. None of the previous histological studies on lepidopteran larval CA reported changes in cell number in relation to age or physiological conditions (Melnikova & Panov, 1975;Takeda, 1978;Yin &Chippendale, 1979). The number of cells, about 150, in CA of M.sexta is much larger than that reported for other Lepidopteran species (Melnikova & Panov, 1975;Takeda, 1978;Yin &Chippendale, 1979).…”