Role of urine in the spawning of female rose bitterling, Rhodeus ocellatus ocellatus

Abstract

This study clarified the spawning mechanism of female rose bitterling, Rhodeus ocellatus ocellatus, with special emphasis on the physical role of urine. Ovulated females ingested a significantly greater quantity of water by drinking than non-ovulated fish. The body weight of ovulated females increased about 1.3% while it decreased 1.0% in non-ovulated females. Urine volume in the urinary bladder increased rapidly before spawning, synchronized with the spawning cycle. On the other hand, little urine remained in specimens which had completed spawning. Histological observation demonstrated that the oviduct and the ureter joined at the proximal part of the ovipositor. On the basis of these anatomical and physiological results, it is proposed that urine plays the physical role of pushing the ovulated eggs through the elongated ovipositor during spawning.

Transitions of urine flow rate and kidney-somatic index in mature masu salmon

“…In female rose bitterling Rhodeus ocellatus ocellatus, ovulated females ingested lager amounts of water than nonovulated females; the urine accumulated prior to spawning acts as the pressure mechanism to eject the ovulated egg when it reaches the proximate section of the ovipositor. 28 Based on these reports and our information, it is found that kidneys in many fish species are functionally modified during the spawning season.…”

Transitions of urine flow rate and kidney-somatic index in mature masu salmon

“…In female rose bitterling Rhodeus ocellatus ocellatus, ovulated females ingested lager amounts of water than nonovulated females; the urine accumulated prior to spawning acts as the pressure mechanism to eject the ovulated egg when it reaches the proximate section of the ovipositor. 28 Based on these reports and our information, it is found that kidneys in many fish species are functionally modified during the spawning season.…”

The reproductive ecology of the European bitterling (Rhodeus sericeus)

“…Duyvené de Wit (1955) and Wiepkema (1961) describe the sequence of events involved in oviposition. The role of urine in oviposition was proposed by Bretschneider & Duyvené de Wit (1947) and confirmed by Matsubara (1994) in Rhodeus ocellatus. In females that are ready to spawn, the ovipositor is extended and appears flaccid.…”

Seasonal change in the spatial utilization of host mussels in relation to ovipositor length by female rosy bitterling Rhodeus ocellatus kurumeus

“…4). A female oviposits by contracting a special structure called the conical organ, thereby forcing the eggs along the ovipositor under the pressure of urine that collects behind the eggs (Matsubara, 1994). It is possible that ovipositon by females with longer ovipositors may be more costly to females, either through a greater energetic expenditure or by a reduced spawning frequency.…”

“…During the breeding period (from April to August), cyclical changes in ovipositor length, which are repeated at intervals of c . 6–9 days, were divided into four phases (Yokote, 1958; Shirai, 1962): ovulation phase, the ovipositor lengthens rapidly in a day, and ova maturation and ovulation occurs overnight (Matsubara, 1994); oviposition phase, the ovipositor reaches its maximum length that lasts c . 1 or 2 days and at this time spawning occurs; post‐oviposition phase, after spawning, the ovipositor reduces in length rapidly in about a day and at this time females have no mature eggs; resting phase, the ovipositor becomes shorter for 3 or 4 days and at this time females have no mature eggs.…”

“…Studies on fluctuation in ovipositor length, and the mechanism for releasing eggs through the ovipositor may provide insight into the evolution of the spawning symbiosis between bitterling and mussels. During the breeding period (from April to August), cyclical changes in ovipositor length, which are repeated at intervals of c. 6-9 days, were divided into four phases (Yokote, 1958;Shirai, 1962): ovulation phase, the ovipositor lengthens rapidly in a day, and ova maturation and ovulation occurs overnight (Matsubara, 1994); oviposition phase, the ovipositor reaches its maximum length that lasts c. 1 or 2 days and at this time spawning occurs; postoviposition phase, after spawning, the ovipositor reduces in length rapidly in about a day and at this time females have no mature eggs; resting phase, the ovipositor becomes shorter for 3 or 4 days and at this time females have no mature eggs. Although it is reported that the periodic fluctuations in ovipositor growth coincide with morphological changes in the ovary (Yokote, 1958;Shirai, 1962;Nishi & Takano, 1979), there are few studies that have examined the seasonal dynamics of the ovipositor length and conditions inside the gill chamber of mussels.…”

Transitions of urine flow rate and kidney-somatic index in mature masu salmon

“…In female rose bitterling Rhodeus ocellatus ocellatus, ovulated females ingested lager amounts of water than nonovulated females; the urine accumulated prior to spawning acts as the pressure mechanism to eject the ovulated egg when it reaches the proximate section of the ovipositor. 28 Based on these reports and our information, it is found that kidneys in many fish species are functionally modified during the spawning season.…”

The reproductive ecology of the European bitterling (Rhodeus sericeus)

“…Duyvené de Wit (1955) and Wiepkema (1961) describe the sequence of events involved in oviposition. The role of urine in oviposition was proposed by Bretschneider & Duyvené de Wit (1947) and confirmed by Matsubara (1994) in Rhodeus ocellatus. In females that are ready to spawn, the ovipositor is extended and appears flaccid.…”

Seasonal change in the spatial utilization of host mussels in relation to ovipositor length by female rosy bitterling Rhodeus ocellatus kurumeus

“…4). A female oviposits by contracting a special structure called the conical organ, thereby forcing the eggs along the ovipositor under the pressure of urine that collects behind the eggs (Matsubara, 1994). It is possible that ovipositon by females with longer ovipositors may be more costly to females, either through a greater energetic expenditure or by a reduced spawning frequency.…”

“…During the breeding period (from April to August), cyclical changes in ovipositor length, which are repeated at intervals of c . 6–9 days, were divided into four phases (Yokote, 1958; Shirai, 1962): ovulation phase, the ovipositor lengthens rapidly in a day, and ova maturation and ovulation occurs overnight (Matsubara, 1994); oviposition phase, the ovipositor reaches its maximum length that lasts c . 1 or 2 days and at this time spawning occurs; post‐oviposition phase, after spawning, the ovipositor reduces in length rapidly in about a day and at this time females have no mature eggs; resting phase, the ovipositor becomes shorter for 3 or 4 days and at this time females have no mature eggs.…”

“…Studies on fluctuation in ovipositor length, and the mechanism for releasing eggs through the ovipositor may provide insight into the evolution of the spawning symbiosis between bitterling and mussels. During the breeding period (from April to August), cyclical changes in ovipositor length, which are repeated at intervals of c. 6-9 days, were divided into four phases (Yokote, 1958;Shirai, 1962): ovulation phase, the ovipositor lengthens rapidly in a day, and ova maturation and ovulation occurs overnight (Matsubara, 1994); oviposition phase, the ovipositor reaches its maximum length that lasts c. 1 or 2 days and at this time spawning occurs; postoviposition phase, after spawning, the ovipositor reduces in length rapidly in about a day and at this time females have no mature eggs; resting phase, the ovipositor becomes shorter for 3 or 4 days and at this time females have no mature eggs. Although it is reported that the periodic fluctuations in ovipositor growth coincide with morphological changes in the ovary (Yokote, 1958;Shirai, 1962;Nishi & Takano, 1979), there are few studies that have examined the seasonal dynamics of the ovipositor length and conditions inside the gill chamber of mussels.…”

Transitions of urine flow rate and kidney-somatic index in mature masu salmon

“…In female rose bitterling Rhodeus ocellatus ocellatus, ovulated females ingested lager amounts of water than nonovulated females; the urine accumulated prior to spawning acts as the pressure mechanism to eject the ovulated egg when it reaches the proximate section of the ovipositor. 28 Based on these reports and our information, it is found that kidneys in many fish species are functionally modified during the spawning season.…”

The reproductive ecology of the European bitterling (Rhodeus sericeus)

“…Duyvené de Wit (1955) and Wiepkema (1961) describe the sequence of events involved in oviposition. The role of urine in oviposition was proposed by Bretschneider & Duyvené de Wit (1947) and confirmed by Matsubara (1994) in Rhodeus ocellatus. In females that are ready to spawn, the ovipositor is extended and appears flaccid.…”

Seasonal change in the spatial utilization of host mussels in relation to ovipositor length by female rosy bitterling Rhodeus ocellatus kurumeus

“…4). A female oviposits by contracting a special structure called the conical organ, thereby forcing the eggs along the ovipositor under the pressure of urine that collects behind the eggs (Matsubara, 1994). It is possible that ovipositon by females with longer ovipositors may be more costly to females, either through a greater energetic expenditure or by a reduced spawning frequency.…”

“…During the breeding period (from April to August), cyclical changes in ovipositor length, which are repeated at intervals of c . 6–9 days, were divided into four phases (Yokote, 1958; Shirai, 1962): ovulation phase, the ovipositor lengthens rapidly in a day, and ova maturation and ovulation occurs overnight (Matsubara, 1994); oviposition phase, the ovipositor reaches its maximum length that lasts c . 1 or 2 days and at this time spawning occurs; post‐oviposition phase, after spawning, the ovipositor reduces in length rapidly in about a day and at this time females have no mature eggs; resting phase, the ovipositor becomes shorter for 3 or 4 days and at this time females have no mature eggs.…”

“…Studies on fluctuation in ovipositor length, and the mechanism for releasing eggs through the ovipositor may provide insight into the evolution of the spawning symbiosis between bitterling and mussels. During the breeding period (from April to August), cyclical changes in ovipositor length, which are repeated at intervals of c. 6-9 days, were divided into four phases (Yokote, 1958;Shirai, 1962): ovulation phase, the ovipositor lengthens rapidly in a day, and ova maturation and ovulation occurs overnight (Matsubara, 1994); oviposition phase, the ovipositor reaches its maximum length that lasts c. 1 or 2 days and at this time spawning occurs; postoviposition phase, after spawning, the ovipositor reduces in length rapidly in about a day and at this time females have no mature eggs; resting phase, the ovipositor becomes shorter for 3 or 4 days and at this time females have no mature eggs. Although it is reported that the periodic fluctuations in ovipositor growth coincide with morphological changes in the ovary (Yokote, 1958;Shirai, 1962;Nishi & Takano, 1979), there are few studies that have examined the seasonal dynamics of the ovipositor length and conditions inside the gill chamber of mussels.…”