Int. J. Insect MorphoL & Embryol. 6(5/6): 345-347. 1977. Pergamon Press. Printed in Great Britain.
SCIENTIFIC NOTE NEUROHAEMAL
ORGAN
IN RHODNIUS
(HETEROPTERA
PROL1XUS STAL
: REDUVIIDAE)
S. A. FARUQU! Department of Zoology, University of Saugar, Sagar (M.P.), India
(Accepted 31 May 1977) THE STUDI~Sof the neuroendocrine complex of heteropteran insects have revealed that the "lame fibrogliale" tissue (Cazal, 1948), cardioglial tissue (Junqua, 1956), corpora cardiaca (Nayar, 1956; Ewen, 1962a; Wigglesworth, 1964; Gupta, 1970; Pathak, 1974), or the aorta (Dogra, 1967a, b; Awasthi, 1972, 1975a, b; Faruqui, 1974, 1975a, b) serve as neurohaemal organs for the median cells secretion. After conducting an extensive study of heteropteran bugs, Faruqui (1975c), concluded that it is the aorta which serves as the neurohaemal organ in these insects, and not the corpora cardiaca (CC) or the cardioglial tissue as had been reported eadier. But when Rhodnius prolixus, was studied by Ewen's (1962b) and Harker's (personal communication) paraldehyde fuchsin (PF), Gomori's (1941) chrome alum haematoxylin-phloxine (CAHP), Delphin's (1963), alcian blue-phloxine (ABP), and Dogra and Tandan's (1964) performic acid victoria blue (PAVB) techniques, it was found to have a neurohaemal organ that is very different from those of other insects. In R. prolixus, the posterior portions of the CC are fused with the aorta wall in that region. Large deposits of the neurosecretory material (NSM) elaborated by the median A-cells are also seen in this region. The CC or the distal part of the aorta are devoid of NSM. It is therefore, concluded that in this insect neither CC nor the aorta serves as the neurohaemal organ, but it is the tissue formed as a result of the fusion of posterior parts of the CC with the aorta, which form the main neurohaemal organ for median cells secretion. The neuroendocrine system of Rhodnius, in general, resembles that of other heteropterans (Faruqui, 1975b) but the nervi corporis cardiaci I (NCC I) in this insect show a somewhat unusual relationship. In all the other heteropterans so far studied, the NCC I of the 2 sides run downwards attached to the inner lateral sides of the CC and enter the aorta wall. In Rhodnius, the NCC I, after emerging from the brain, travel a short distance to reach the posterior fused part of the 2 corpora cardiaca (Figs. I, 2). Large quantities of stored NSM are seen in this region, formed as a result of the fusion of CC and aorta. All the axons, except a few (2-3), are seen to terminate in this region, after forming a thick network of secondary axons. This network retains the NSM. About 2-3 axons, loaded with NSM, are also seen to travel a very short distance in the aorta (Fig. 3). A few secondary ones are seen to penetrate the corpora allata (Fig. 4). Cazal (1948) and Junqua (1956) have reported the formation of structures termed "lame fibrogliale" and "Cardiogliar' respectively, as a result of the fusion of parts of CC and the aorta in cryptoceratan species studied by them. But later studies by Dogra (1967b, 1969), Awasthi (1973b), and Faruqui (1974, 1975a) contradicted these findings, and reported the CC and the aorta to be independent of each other. In insects other than heteropterans, the CC serve as neurohaemal organs for cerebral NSM. Thus, there are only two well-recognised neurohaemal organs in insects, viz. the CC and the aorta. But in thisinsect thepart of the CC fused with aorta, serves this function. Such a structure is not seen in any other insect. This represents a transitional stage between a typical orthopteroid condition, where the CC serve as the neurohaem ' organs and the heteropteran condition where the aorta serves as the neurohaemal organ for median ce NSM. Such transitional stages may be of evolutionary importance in the development of neuroendocrine systems.
Acknowledgements--The author is thankful to Prof. R. S. Saini and Dr. D. P. Gupta for suggestions and guidance and to Prof. Sir V. B. Wigglesworth and Dr. S. H. P. Maddrell for providing the eggs and adults of Rhodnius from their department (Cambridge University). This investigation was supported by a research grant of University Grants Commission, India. REFERENCES AwAsral, V. B. 1972. Studies on the neurosecretory system and retrocerebral endocrine glands of Nezara viridula. Linn. (Heteropetra: Pentatomidae). J. MorphoL 136: 337-352. AWASTrH, V. B. 1973a. Neurosecretory systems and the retrocerebral endocrine glands of Metochus uniguttatus. Thunb. (Heteroptera: Lygaeidae). Int. J. Insect Morphol. Embryol. 2:1-12. 345
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Awmrm, V. B. 1973b. Studies/n situ on the neurosecretory system of Splmerodema rusticum. Fabr. (Heteropetra: Bclostomatidae). ZooL Beitr. 19: 151-156. CAZAL, M. 1948. Les #ands endocrines r6troc~r6brales des insectes (l~tude/Morphologique). Bull. Biol. Fr. Belg. (Suppl.) 32: 1-227. DELPmN, F. 1963. Studies on Neuro~cretion in Schistocerca gregaria. F. (Orthoptera: Acrididae). Ph.D. Thesis, Univ. London. (Not seen in original.) DOORA,G. S. 1967a. Studies on the neurusecretory system and the functional significance of NSM in the aorta wall of the bug, Dysdercus koenigii. J. Insect Physiol. 13:1895-1906. DocmA, G. S. 1967b. Studies on the neurosecretory system of Ranatra elongata. Fabricus. (Hemi0tera: Nepidae) with reference to the distal fate of NCC I and II. J. Morphol. 121: 223-40. DOORA,G. S. 1969. Studies in situ on the neurocndocrine system of the giant water bug, Belostoma indica. l_,¢p. Serv. (Heteroptera: Belostomatidae). Acta Anat. 72: 429-45. DOGRA,G. S. and B. K. TANDON.1964. Adaptations of certain histological techniques for in situ demonstration of the neuroendocrine system of insects and other animals. J. Microsc. Sci. 105: 455-66. EWEN, A. B. 1962a. Histophysioiogy of the neurosecretory system and retrocerebral endocrine #ands of the alfalfa plant bug, Adelphocoris lineolatus Goeze. (Hemiptera: Miridae). J. Morphol. 111: 255-273. EW~N, A. B. 1962b. An improved aldehyde fuchsin staining technique for neurosecretory products in insects. Trans. Amer. Microsc. Soc. 81: 94-6. FARUQUI,S. A. 1974. Neurosecretory system and retrocerebral endocrine #ands of Sphaerodema rusticum. Fabr. (Heteroptera: Belostomatidae). Zool. Jahrb. Anat. 92: 416-29. FARUQUI,S. A. 1975a. Studies on the neurosecretory system and retrocerebral endocrine #ands of Ranatra filiformis. Fabr. (Hemiptera), using the techniques specific for cystine and/or cysteine. Anat. An2. 137: 454--61. FARUQUI,S. A. 1975b. Neurosecretory system and retrocerebral endocrine glands of Leptocorisa acuta. Thunb. (Heteroptera: Coreidae). Folia Morphol. 22(3): 261-67. FARUQUI,S. A. 1975c. Studies on the neuroendocrine complex of Heteroptera. Ph.D. Thesis, Univ. Saugar, India. GOMARt, G. 1941. Observations with differential stains on human islets of Langerhans. Amer.J.Pathol. 17: 395--406. GUPTA, D. P. 1970. Neurosecretory cells in Dysdercus similis (Hemiptera). J. ZooL Lond. 162: 401--411. JUNQUA, C. 1956. Etude morphologique et histophysiologique des organs endocrine de l'Hydrocyrius columbiae Spin. (H6mipt6res: Bellostomides). Bull. BioL 90:154--62. NAVAR, K. K. 1956. Studies on the neurosecretory system of lphita limbata Stall. III. The endocrine glands and the neurosecretory pathways in the adult. Z. Zellforsch. 44: 697-705. PATnAK, S. C. 1974. Studies on the corpus aUatum of insects. Ph.D. Thesis, Jiwaji Univ. Gwalior, India. WIGOLESWORTn,V. B. 1964. Life o/Insects. Weidenfeid and Nicholson, London.
F ~ . 1. Horizontal section of corpus cardiacum (CC) and aorta. Depositions of neurosecretory material is seen in posterior fused part of CC and aorta. × 600. Fro. 2. Horizontal section through CC. Note course of NCC I (It is seen to bypass CC). × 400. FIG. 3. Horizontal section through cardioglial tissue CA and aorta. 2-3 axons are seen in the aorta. × 450. FIG. 4. Horizontal section through cardioglial tissue, showing innervation of corpora allata (C by axons of A-cells. Deposits of NSM are also seen in the #and. × 400. ABBREVIATIONS USED IN FIGURES A# Aorta. Ax Axon. CA Corpus allatum. CC Corpus cardiacum. Cgt Cardio#ial tissue. NCA Nervi ¢orporis allati. NCC I Nervi corporis cardiaci I. NSM Neurosecretory material.