Proc. Indian Acad. Sci. (Anita. Sci.), Vol. 89, Number 5, September 1980, pp. 431-439. ¢~) Printed in India.

Copepod parasites of fishes of Waltair coast: Anatomy of the female reproductive system of Pseudocycnus appendiculatus Heller, 1865

D V UMA DEVI, K SHYAMASUNDARI axtd K HANUMANTHA RAO Department of Zoology, Andhra University, Waltair 530 003, India

MS received 22 November 1979

Abstract. The anatomy of the reproductive system of Pseudocycnus appendiculatus (Copepoda : Pseudocycnidae) has been described. The system consists of a pair of ovaries, oviducts, cement gland, spermatheca, sperm tube and egg sacs. All except the egg sacs are located in the trunk region.

Keywords. ; parasites ; anatomy ; female reproductive system ; Pseudo- cycnus appendiculatus.

L Introduction Considerable information on the anatomy of the reproductive system is available. In general the Macrura and Branchyura attracted greater attention. The general arrangement of the pattern of reproductive system is not uniform in all copepod parasites. There is considerable confusion as to what is included in the term ovary, the relationships of the ovary, oviduct and body cavity. There are several reports on the internal anatomy of copepod parasitised invertebrate hosts like annelids, holothurians and ascidians (Caullery and Mesnil 1915, 1917, 1918, 1919; Goulliart 1937; Bresciani and Liitzen, 1961a, b, 1966, 1972, 1974; Liitzen 1964, 1966, 1968; Bocquet et al 1968, 1970). The details of the anatomy of which parasitise fishes have been scanty. Wilson (1911, 1915) described in detail the embryological development of percarum and morphological and histological descriptions formed the basis of a revision of the entire family Lerna~opodidae. Gray (1928) gave a detailed description of the different zones in the ovary, oocytes, the oviduct and their associated structures. He has described in detail the formation of mature ovum. E1 Saby (1933) dealt with the description of the reproductive organs of six species of copepod parasites belonging to different families. Grabda (1958) described the male reproductive system of Achtheres percarum. He reported the results of an anatomical study of the female reproductive system of Achtheres per- carum, Tracheliastes maculatus, Tracheliastes polycolpus and Basanistes huchonis. 431 432 D V Uma Devi, K Shyamasundari and K Hanumantha Rao Reigby and Tunnel (1971) gave an account of the histology of the female reproduc- tive system of Pseudochropinus dentatus. Rousset et al (1978) illustrated the reproductive apparatus of Chondracanthus angustatus.

2. Materials and methods

Specimens of Pseudocycnus appendiculatus were collected from the gills of tuna Euthynnus aj~nis a~nis. After routine processing 10/t sections were cut and stained with tteidenhain's Azan, Masson's trichrome and Mallory's triple stains. These stains gave sharp results. With these nuclei took a deep pink colour and stood out conspicuously. Ovary and ooeytes took an orange colour, cement gland red and spermatheca blue. This faciIitated the study of the histological details.

3. Results The reproductive system of eopepod parasites in general comprises the following parts: (a) paired ovaries, (b) oviducts, (c) cement gland, (d) spermatheca (seminal receptacle), (e) sperm tube and (f) egg sacs. All except the egg sacs are located in the trunk region. A pair of small ovaries (Germinal epithelium) is located on either side of the stomach. The ovary is globular to oval in shape. They lie at the anterior end in the second thoracic segment (figure I), dorsal to the stomach and a short distance from the maxilliped gland, this region corresponds to the first zone of Gray (1928) and Grabda (1958). From the ovaries a cell emerges and lies in a vacuole. This cell has a small spherical nucleus and a thin cell wall. The wall of the vacuole in which it lies forms a ' Pseudomembrane '. This cell undergoes rapid proli- feration and migrates inwards. The resulting numerous cells lie attached in rows forming short strings. Strings which are discoidal in shape pass down the ovi- ducts. The end cell of each string enlarges considerably and represents almost a fully formed ovum. It is the largest cell in the string with smaller cells just opposed to it. Each oviduct arises from a postero-ventral end of the ovary as a narrow tube which runs parallel to the stomach towards the posterior end. As the cells in the strings increase in number and travel into the interior, the oviduct swells up so as to fill the whole cavity. The wall of the oviduct becomes convoluted (figure 2) at regular intervals due to the presence of bands of striped muscles (figure 3). As the oviduct gets filled with oocytes it expands considelably and along with this the posterior part of the trunk tends to bulge. Each oviduct turns almost to the middle line and then proceeds lateralwards before it opens into the egg sac (figure 4). Mature and fertilized eggs pass into the egg sacs. On each side lateral to the oviduct there is a tubular cement gland (figure 5). It is slightly convex on the dorsal side. Two regions could be distinguished in the cement gland. The outer region is lined by a cellular wall and the inner region is filled with fine grained matrix (figure 6). Actually cement substances are secreted by the cellular wall and it is in the inner region that the egg gets a coating while passing into the egg sacs, The cement gland opens into the oviduct b), a tube (figure 5). Reproductive system in P. appendiculatus 433

Figures 1-3. 1. Sagittal section showing the ovaries (OV = ovary). 2. Section showing the convoluted oviduct. 3. Sagittal section passing through the oviduct showing the muscle bands at regular intervals (Azan). MB=mlJscle bands. 434 D V Uma Devi, K Shyamasundari and K Hanumantha Rao

Figures 4-6. 4. Section passing through the posterior part of the body showing the opening of oviduct into egg sac. (OOV ~ opening of oviduct; ES ~ egg sac). 5. Section showing the opening of cement gland into oviduct (CG --cement gland ; OCG = opening of cement gland). 6. Transverse section passing through the cement gland showing the outer cellular and inner matrix regions (OC = outer cellular ; IM = inner matrix). Reproductive system in P. appendiculatus 435

k..~L.-.,L k: ~]i

i ~i ~~,

Figures 7-9. 7. Section showing the opening of spermatheca into oviduct(OSM~-~- opening of spermatheca into oviduct). 8. Transver~ section of spormatheea showing the structure (note the mesenchymatous and fibrillary structure) 9. Sec- tion showing the sperm tube. (ST ~ sperm tube).

Reproductive system in P. appendiculatus 437 Another structure associated with reproduction is an unpaired sac, the sperma- theca. This is a closed sac opening posteriorly. It acts as a reservoir for the storage of sperms and constitutes the receptaculum seminis. After travelling poste- riorwards to a considerable distance it joins the oviduct by a small tube (figure 7). Receptaculum seminis is covered by a tough epithelium and is surrounded by a thick mesenchymatous and fibrillary structure (figure 8). It opens out by two tubes through which sperms enter from male during copulation (figure 9).

4. Discussion Aspects of internal anatomy of the female reproductive system of Pseudocycnus appendiculatus agree in many details with previous findings reported by several authors for the parasitic copepods. However, there are certain differences. In Pseudocycnus appendiculatus a pair of spherical ovaries lie in the second thoracic segment, dorsal to the stomach and a short distance behind the maxilliped gland. Each oviduct arises from the posterior ventral end of the ovary. The term ovary, oviduct and the relationship of the ovary, oviduct with body cavity are some points of controversy. Wilson (1911, 1915) and E1 Saby (1933) described the ovary lying in the cephalothoracic region just posterior to the maxilli- pedal glands. AceoIding to them the oviducts pass posteriorly into the trunk whele they get filled up with oocytes and get expanded to fill the entire body cavity. Gray (1928) could never trace the presence of ovaries in the cephalothorax of Lernaeopoda scyllicola. According to Grabda (1958) the ovaries in Achtheres are situated above the vulvae and extend along the length of the body on either side of the intestine. According to Rigby and Tunnell (1971) the ovary in Pseudo- charopinus dentatus is just a tissue which they termed as germinal epithelium. They further stated that ova are produced by the germinal epithelium, later they mature in the body cavity and get separated from the germinal epithelium proper. The body cavity serves as a maturation and storage area. Gray (1928) could distin- guish three separate zones in the ovary of Lernaeopoda scyllicola, r.,amely germinal epithelium, zone of production and a zone of formation. Anything equivalent to the zone or production and formation could not be traced in P. appendiculatus. In P. appendieulatus the ova pass down the oviduct which swell ard push the ali- mentary canal to a side. These ova in their passage down the oviduct are ferti- lised, cemented and passed into the oviducts. The oviduct is convoluted with bands of striped muscles at regular intervals. Wilson (1911, 1915) strted that attached to the oviduct there are some uterine processes in which the eggs mature, and he also noticed convolutions of the oviduct. E1 Saby (1933) could trace neither the convolutions of the oviduct nor the uterine processes in the six species, Acanthochondria depressa, Chondracanthus merluccii, Brachiella merluccii, Brachiella obesa, Parabrachiella insidiosa and Clavella uncinata he studied. According to Gray (1938) the wall of the oviduct of Lernaeopoda scyllicola is ringed at intervals with bands of striped muscles The filamental cells connecting the older cells have been first observed by Claus (1861) in Achtheres. van Beneden (1870) discovered them in Anchorella and Lernaeopoda. According to these authors these filament cells are secreted by th~ wall of the ovary. 438 D V Uma Devi, K Shyamasundari and K ttanumantha Rao

In P. appendiculatus the cement gland is a long tubular structure opening into the posterior part of the oviduct before the later opens into the egg sac. It is a sepa- rate structure and not a modification of the part of the oviduct. The cement gland could be divided into two regions. The outer region is made up of cellular wall and this region secretes the cement necessary for the eggs. The inner region is filled with the fine grained matrix which is actually responsible for coating eggs before they pass into the egg sacs. Wilson (1915) stated that there are three regions in the cement gland, an anterior terminal portion, a central broader portion and a posterior basal portion. Gray (1928) mentioned that the oviductal wall of Lernaeo- poda scyllicola gets modified to form the cement gland and it is crescentric in sec- tion. Grabda (1958) located the cemept gland inside the oviduct in all the four species he examined. Rigby and Tunnell's (1971) description of the cement gland in Pseudocharopinus dentatus agrees with what is found in Lernaeopoda scyllicola. Another structure associated with the female reproductive system is spermatheca. It is an unpaired structure closed in front and opening behind into the oviduct by one duct and outside by two ducts. Spermatozoa are stored inside it. Except in Parabrachiella insidiosa in other species examined by E1 Saby (1933) an unpaired spermatheca was observed. In Lernaeopoda scyllicola the spermatheea is a bifur- cated structure, each arm being connected by a sperm tube to the exterior (Gray 1928). Spermatheca is connected to the oviduct by a tube.

Acknowledgements

One of us (DVU) is grateful to the Council of Scientific and Industrial Research, New Delhi, for financial assistance.

References Bocquet C, Bocquet-V6drine J and L'Hardy J P 1968 Analyse des rapports du Cop6pode para- site Xenocoeloma alleni (Brumpt) et de son h6te Polycirrus caliendrum Clapar~de ; Cab. Biol. Mar. 9 285-296 Bocquet C, Bocquet-V~drineJ and L'Hardy J P 1970 Contribution hl'6tude du developement des organes g6nitaux chez Xenocoeloma alleni (Brumpt), Cop6pode parasite de Polycirrus caliendrum Clapar6de; Cah. Biol. Mar. 11 195-208 Bresciani J and Liitzen J 1961a The anatomy of a parasitic copepod, Saccopsis steenstrupi n. sp. ; Crustaceana 3 9-23 Bresciani J and LiJtzen J 1961b Gonophysema gullmarensis (Copepoda Parasitica). II. Biology and Development; Cah. Biol. Mar. 2 347-371 Breseiani J and LiJtzen J 1966 The anatomy of Aphanodornus terebellae (Levinsen) with remarks on the sexuality of the family Xenocoelomidae nov. fam. (Parasitic Copepoda) ; Bull. Mus. Natn. Hist. Nat. Paris 37 787-806 Bresciani J and Liitzen J 1972 The sexuality of Aphanodomus (Parasitic Copepod) and the pheno- menon of cryptogonochorism ; Vidensk. Medd. Dan. Naturhist. Foren. 135 7-20 Bresciani J and Liatzen J 1974 On the biology and development of Aphunodomus Wilson (Xeno- coelomidae) a parasitic copepod of the polychaete Thelepus cincinnatus; Vidensk. Medd. Dan. Naturhist. Foren. 137 25-63 Caullery M and Mesnil F t915 Sur la structure et les rapports avec l'h6te (Polycirrus arenivorus Caull.) d'un Cop6pode parasite (Xenocoeloma brumpti n.g., n. sp.) ; C.R. Acad. Sci. Paris 161 709-712 Caullery M and Mesnil F 1917 Nouvelles recherches sur Xenocoeloma brumpti C. et M ; Bull, See. Zool. France 42 169-178 Reproductive system in P. appendiculatus 439 caullery M and Mesnil F 1918 Phases parasitaires initiales du Xenocoeloma brumpti; C.R. Aead. Sci. Paris 167 964-966 Caullery M and Mesnil F 1919 Xenocoeloma brumpti C. et M. Cop6pode parasite de Polycirrus arenivorus C ; Bull. Biol. France Belg. 53 161-233 Claus C 1861 Uber den Bau und die Entwicklung yon Achtheres percarum ; Z. Wiss. Zool. 2 287-308 El Saby M K 1933 The internal anatomy of several parasitic copepoda ; Prec. Zool. Soc. London (Pt. 4) PP. 861-869 Goulliart M 1937 Recherches sur les Cop6podes parasites : biologies, spermatog6n~se et ovog6n6se; Tray. Sta. Wimereux. 12 309-457 Grabda J 1958 Structure of the sexual organs in some representatives of the family (Copepoda: Parasitica) ; Zool. Polon. 9 154-160 Gray P 1928 The internal anatomy of Lernaeopoda scyllicola Leigh-Sharpe. Part I. The female ; Q. J. Microsc. Sci. 72 487-509 Liitzen J 1964 The type of sexuality in Gonophysema, Apbanodomus and Xenocoeloma (Parasitic eopcpods of invertebrates).; First Int. Congr. Parasit. Rome 2 1077-1078 Liitzen J 1966 The anatomy of the family Herpyllobiidae (Parasitic copepods) ; Ophelia 3 45-64 Liitzen J 1968 On the biology of the family Herpyllobiidae (Parasitic copepods) ; Ophelia 5 175-187 Rigby D W and Tunneil N 1971 Internal anatomy and histology of female Pseudocharopinus dentatus (Copepoda, Lemaeopodidae); Trans. Am. Microsc. Soc. 90 61-71 Rousset V, Raibaut H, Manier J F and Coste F 1978 Reproduction and sexuality of parasitic copepods of fishes I. The reproductive apparatus of Chondracanthus angustatus Heller, 1863. Anatomy, histology and spermatogenesis; Z. Parasitenk. 55 73-83 van Beneden P J 1870 Les poissons des cotes de Belgique, leurs parasites et leur commensaux ; Bull. Acad. R. Soc. Belg. 38 1-100 Wilson C B 1911 North American parasitic copepods. Part 9. The Lernaeopodidae ; Prec. U.S. Natl. Mus. (1783) 39 189-226 Wilson C B 1915 North American parasitic copepods belonging to the family Lernaeopodidae with a revision of the entire family ; Prec. U.S. Natl. Mus. (2063) 47 565-729