Microscopic structures of the ovary and female genital ducts of Supachai's caecilian, Ichthyophis supachaii Taylor, 1960 (Amphibia: Gymnophiona)

Abstract

Pewhom, A., Chumnanpuen, P., Muikham, I., Chatchavalvanich, K. and Srakaew, N. 2015. Microscopic structures of the ovary and female genital ducts of Supachai's caecilian, Ichthyophis supachaii Taylor, 1960 (Amphibia: Gymnophiona). -Acta Zoologica (Stockholm) 00: 000-000.The structures of the female reproductive system (ovary, oviduct and cloaca) of Ichthyophis supachaii were investigated by dissection, histology and light microscopy. Paired, elongated, sac-like ovaries are parallel to the gut and fat bodies. Follicle stages include germinal nests of oogonia and primary oocytes, early and late previtellogenic follicles, early and late vitellogenic follicles and atretic follicles. Germinal nests of oogonia comprise oogonia and prefollicular cells. Nests of primary oocytes contain clusters of synchronously developing primary oocytes enclosed by connective tissue. Primary oocytes are associated with follicular cells. Previtellogenic follicles initially form the vitelline envelope, theca cell layers and patches of ooplasmic glycoproteins. Vitellogenic follicles contain heterogeneously sized spherical yolk granules. Atresia is present in several stages of developing follicles. The oviduct is divided into the anterior, middle and posterior parts. All oviductal parts are lined by non-ciliated epithelium. A small number of mucous cells are present in the middle part. The cloaca of female I. supachaii is divided into the anterior and posterior chambers. The anterior chamber is lined by glandular stratified columnar epithelium, while the posterior chamber has stratified cuboidal epithelium with less mucus production. Our results contribute to useful information on the reproductive biology of caecilians.

Microanatomy of the digestive system of Supachai's caecilian,Ichthyophis supachaiiTaylor, 1960 (Amphibia: Gymnophiona)

“…Mucosubstances are present throughout the digestive tract of I. supachaii from the oral cavity to the intestine, as described in this study, and in the cloaca, as reported in previous studies (Pewhom et al 2015(Pewhom et al , 2016. The distribution patterns of glycoconjugates along the digestive tract of I. supachaii exhibit regional variation and possibly interspecific variation, compared to other caecilians, including I. glutinosus (Zylberberg 1977), Caecilia gracilis, H. rostratus, M. unicolor, T. compressicauda (Exbrayat 1996(Exbrayat , 2003, S. annulatus (Junqueira et al 1999) and I. cf.…”

“…While the oesophageal longitudinal folds and gastric rugae do not seem to alter the total surface areas of the oesophagus and the stomach, respectively, the intestinal folds increase the intestinal surface areas for enzymatic digestion and nutrient absorption, like the mammalian intestinal villi (Ross and Pawlina 2015). However, the intestinal folds of I. supachaii are structurally different from the avian and mammalian villi of which the lamina propria possesses the central lacteal and the base leads into the intestinal tubular glands (crypts of Lieberk€ uhn; Andrew and Hickman 1974;Ishikawa et al 1985;Chikilian and de Speroni 1996;Reynolds and Rommel 1996;Zaher et al 2012) Mucosubstances are present throughout the digestive tract of I. supachaii from the oral cavity to the intestine, as described in this study, and in the cloaca, as reported in previous studies (Pewhom et al 2015(Pewhom et al , 2016. The distribution patterns of glycoconjugates along the digestive tract of I. supachaii exhibit regional variation and possibly interspecific variation, compared to other caecilians, including I. glutinosus (Zylberberg 1977), Caecilia gracilis, H. rostratus, M. unicolor, T. compressicauda (Exbrayat 1996(Exbrayat , 2003 (Zylberberg 1977), Hyla japonica, Pelophylax nigromaculatus (formerly Rana nigromaculata), Xenopus laevis (Suganuma et al 1981), R. aurora aurora (Ferri et al 2001), P. viridis and Rana temporaria (Liquori et al 2002) and Rhinella icterica (Machado-Santos et al 2014); and urodeles, including Calotriton asper (formerly Euproctus asper), Lissotriton helveticus, Pleurodeles waltii, Salamandra salamandra, Triturus cristatus, T. marmoratus (Zylberberg 1977), Ambystoma mexicanum (Suganuma et al 1981) and T. carnifex (Liquori et al 2007).…”

“…The gallbladder proper is thin and continuous with the cystic duct wall. Neutral and carboxylated acid mucosubstances are secreted along the digestive tract, while sulphated mucosubstances are not produced by the stomach and anterior intestinal regions.Animals C4 and C5 are animals F1 and F2, respectively (see table 1 in Pewhom et al 2015).…”

Anatomy of the female reproductive system and sperm storage of the viviparous caecilian Typhlonectes natans (Gymnophiona: Typhlonectidae)

“…In Ch. indistinctum (Berois, De Sa, 1988) and I. supachai (Pewhom et al, 2015), germinal nests are randomly scattered throughout entire ovary.…”

“…The first descriptions of the female reproductive tract in Gymnophiona were provided by Müller (1832) and Rathke (1852). There have been an increasing number of studies describing the anatomy of the reproductive systems of caecilians including both phylogenetically basal oviparous [Ichthyophis supachaii Taylor, 1960(Pewhom et al, 2015; I. beddomei Peters, 1880(Masood-Parwees, Nadkarni, 1993; I. glutinosus Linnaeus, 1758; Siphonops annulatus Mikan, 1820 (Sarasin, Sarasin, 1887); Gegeneophis ramaswamii Taylor, 1964 (Beyo et al, 2007)] and derived viviparous species [e.g., Chthonerpeton indistinctum Reinhardt, Lütken, 1862 (Berois, De Sa, 1988); Typhlonectes compressicauda Duméril and Bibron, 1841 ], but an understanding of the morphology, anatomy and function of these reproductive systems still lags behind that of anurans and caudates.…”