Reproductive role of attaching filaments on the egg envelope in Xenopoecilus sarasinorum (Adrianichthidae, teleostei)

Abstract

Eggs of Xenopoecilus sarasinorum possess two distinct types of filaments on the surface of the egg envelope (chorion), long, attaching filaments restricted to the vegetal pole and weak, nonattaching filaments around the animal pole (micropyle). Both types are formed during oogenesis. After mature eggs were spawned through the urogenital pore, they were fertilized and hung in an abdominal concavity of the female. Oviposition never took place in the presence of embryos in the concavity because of the retardation of oogenesis. The loosely tangled tips of the attaching filaments that are retained within the ovarian cavity plug the urogenital pore by forming a hard complex with the epithelial cells. Into this plug structure that fuses with the inner wall of the urogenital pore, capillaries are provided. Within 5 days after the initiation of hatching, this plug degenerates and is released from the urogenital pore. Thus, in female X. sarasinorum, the reproductive cycle seems to be regulated by the physiological function ofthe plug structure formed by the attaching filaments in response to the presence of developing embryos.

The untapped potential of medaka and its wild relatives

“…Finally, a new reproductive strategy referred to as “pelvic brooding” has evolved in at least two lineages from Sulawesi (Herder et al, 2012a; Kottelat, 1990). Pelvic brooders do not deposit fertilized eggs, but instead carry their clutch until the fry hatches (Box 2, Iwamatsu, 2004; Iwamatsu et al, 2008; Parenti, 2008). While this innovation likely relies on a complex set of behavioral, physiological and anatomical adaptations, the adaptive benefit of this female investment remains unexplored.…”

“…While most ricefishes deposit fertilized eggs shortly after spawning, pelvic brooders instead carry an egg-clutch in a ventral concavity until the fry hatches (Box 2—figure 1). Pelvic brooding likely relies on a complex set of adaptations (Iwamatsu et al, 2007; Iwamatsu et al, 2008; Kottelat, 1990; Parenti, 2008). Elongated pelvic fins cover the eggs, while a plug structure that is connected to the eggs via attaching filaments anchors them inside the female’s ovarian cavity.…”

“…Elongated pelvic fins cover the eggs, while a plug structure that is connected to the eggs via attaching filaments anchors them inside the female’s ovarian cavity. Ovulation is delayed in pelvic brooders for as long as eggs are attached, and the plug was even assumed to allow the transfer of nutrients, akin to a placenta (Iwamatsu et al, 2008). Despite this complexity, pelvic brooding occurs in at least three species from two lineages, namely Adrianichthys oophorus, Oryzias eversi and Oryzias sarasinorum .…”

Histological Observation of the Urogenital Papillae in the Bi-Directional Sex-Changing Gobiid Fish,Trimma okinawae

“…Several teleost species, including gobiid fish, are known to have attachment filaments distributed over the eggs (Iwamatsu et al, 2008;Kramer and Patzner, 2008). In the medaka, rudiments of attachment filaments have been clearly shown in the area where granulosa cells connect with the oocyte (Iwamatsu and Nakashima, 1996).…”

Frehswater Fish of Lakes and It’s Inlet Rivers in Sulawesi Tengah Province, Indonesia

“…Selain itu, ikan endemik yang berpotensi sebagai ikan hias dan/atau ikan konsumsi dapat mengandalkan hasil akuakultur untuk menghindari penangkapan berlebih (overfishing) karena memenuhi permintaan pasar. Sebagai contoh pada spesies rono endemik Danau Lindu, telah dilakukan penelitian tentang upaya domestikasi (Wilkerson, 2013, Herjayanto et al, 2018, reproduksi (Iwamatsu et al, 2007, Iwamatsu et al, 2008 dan manipulasi reproduksi rono (Melaty, 2018;Sholekha, 2018) sebagai upaya untuk menguasai teknik pemeliharaan dan pengembangbiakan rono di luar habitatnya. Selain itu untuk spesies endemik Danau Poso, upaya domestikasi A. oophorus juga telah dilakukan (Rendi, 2014).…”