Structure and Function of the Salachian Egg Case

Knight, David P.; Feng, Dian; Stewart, Murray

doi:10.1111/j.1469-185x.1996.tb00742.x

Cited by 56 publications

(97 citation statements)

References 53 publications

(85 reference statements)

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“…Their function is the production of the egg case (Hamlett et al, 1998a) and comprises the secretion of a protein polymer similar to a "liquid crystal" through the grooves and that join in the lumen of the gland (Knight et al, 1996). In S. acuta this region seems similar to other oviparous species (Hamlett et al, 1998a, Smith et al, 2004.…”

Section: Discussionmentioning

confidence: 89%

“…An interesting difference in our species is that in not one examined example have we found spermatozoa. The sperm storage is common in elasmobranchs and in most oviparous studies, species spermatozoa were found in the terminal or/and in the baffle zones (Knight et al, 1996;Hamlett et al, 2003, Smith et al, 2004. It is impossible to determine if the absence of sperm in the genital tract of females is due to the sampling zone, or to the season, or to a specific characteristic, but there are other examples of no sperm storage in elasmobranchs (Tricas et al, 2002, Dasyatis sabina).…”

Section: Discussionmentioning

confidence: 98%

“…There is not evidence that the club's jelly was a nutritional function (Koob and Strauss, 1998) rather it may have a support function for the developing embryo (Hamlett et al, 1998b). On the other hand, the papillary's jelly was postulated as a lubricant between egg and case (Nalini, 1940) or, in the case of jelly produced by the last adenomers (intermediate zone), may be interpreted as a demarcation between egg and case (Knight et al, 1996). A more extended investigation about the nature of secretions for clarifying its functions is necessary.…”

Section: Discussionmentioning

confidence: 99%

“…As the fertilized egg passes down the oviduct it is encapsulated by secretions produced by the oviducal gland, which is a specialized region of the oviduct which transfers eggs to the uterus, produces egg jelly, forms the tertiary egg envelopes and stores sperm (Hamlett et al, 1998a;Hamlett and Koob, 1999). The gross morphology of the oviducal gland varies between species, but in general consists of two similar dorsoventral flattened halves surrounded by connective tissue (Knight et al, 1996) and their size changes with the reproductive cycle stage. It can be divided into four different morphological zones based on the appearance of the lamellae in longitudinal view.…”

Section: Introductionmentioning

confidence: 99%

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Histological remarks of the oviduct and the oviducal gland of Sympterygia acuta Garman, 1877

Ej¹,

Estecondo²

2008

Braz. J. Biol.

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The elasmobranchs constitute an important resource in Argentinian fishing and they show reproductive characteristics that make them susceptible to the pressure of fishing. In spite of the importance of the resource our knowledge about the species of the Southwestern Atlantic is scarce. In this work we study the microanatomy of the oviduct and the oviducal gland of Sympterygia acuta. The results show a very folded oviduct with mucous and ciliated cells. The oviducal gland depicts the same zonation as other batoids, showing the typical four regions (club, papillary, baffle and terminal). The epithelium lining the glandular lumen is simple columnar with ciliated and glandular cells. The four zones show simple or ramified tubular gland the secretions of which constitute the egg's envelopes. The club and baffle zones are similar to those present in other species. The papillary one depicts a different pattern of secretions that other Rajiformes and the last zone of the gland is characterized by mixed adenomers. The information here exposed constitutes the first report on the microanatomy of the genital tract of S. acuta.Keywords: Elasmobrachs, oviducalgland, reproduction, Sympterygia acuta. Observações histológicas do oviduto e da glândula oviducal de Sympterygia acuta Garman, 1877 ResumoOs elasmobranchii constituem um importante recurso pesqueiro na Argentina e mostram características reprodutivas que os fazem suscetíveis à pressão de pesca. Apesar da importância do recurso, nosso conhecimento sobre as espécies do Atlântico do Sudoeste é escasso. Neste trabalho, estudamos a microanatomia do oviduto e da glândula oviducal de Sympterygia acuta. Os resultados mostram um oviduto muito dobrado, com células mucosas e células ciliadas. A glân-dula oviducal apresenta as mesmas zonas que outros batóideos, mostrando as quatro regiões típicas (club, papillary, baffle e terminal). O epitélio que reveste o lúmen glandular é simples, com células ciliadas e células glandulares. As quatro zonas mostram glândulas tubulares simples ou ramificadas e suas secreções constituem os envelopes do ovo. As zonas do club e baffle são semelhantes aquelas presentes em outras espécies. A papilar tem um padrão de secreção diferente de outros Rajiformes e a última zona da glândula é caracterizada por adenômeros mistos. A informação aqui exposta constitui o primeiro relato sobre a microanatomia do trato genital de S. acuta.Palavras-chave: Elasmobranchii, glândula oviducal, reprodução, Sympterygia acuta.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Histological remarks of the oviduct and the oviducal gland of Sympterygia acuta Garman, 1877

Ej¹,

Estecondo²

2008

Braz. J. Biol.

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“…The outer surface of the egg case, accounting for ca. 2% of the thickness of the wall, is made of a more darkly coloured and refringent layer that grades into a layer containing many protein granules (Knight & Feng 1994a,b;Knight et al 1996). In the bulk of the wall, each collagen ¢bril contains a quasi-crystalline molecular organization.…”

Section: Introductionmentioning

confidence: 99%

X–ray diffraction analysis of the 3D organization of collagen fibrils in the wall of the dogfish egg case

Knupp

Squire

1998

Proc. R. Soc. Lond. B

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The wall of the egg case of the dog¢sh, Scyliorhinus canicula, contains a network-forming collagen assembled into a regular three-dimensional (3D) structure. It accomplishes supportive, protective and ¢ltering functions for the embryo contained within it. The collagen molecules in the egg case are organized into a body-centred unit cell of dimensions (mean AE s.d.) (11.6 AE 1.0) nm Â (11.6 AE 1.0) nm Â (81.6 AE 3.2) nm, which belongs to the I422 space group. At a higher hierarchical level, the collagen molecules assemble into parallel arrays of ¢brils, ca. 100 nm in diameter, which aggregate to form laminae ca. 0.5 mm thick. These laminae are organized into a plywood-like structure and account for 98% of the thickness of the wall of the egg case. X-ray di¡raction patterns of the wall of the egg case were taken along mutually perpendicular directions, one being perpendicular to the surface of the egg case. Three di¡erent kinds of di¡raction pattern were observed. One of the patterns was characteristic of an X-ray direction perpendicular to the laminae in the egg case (along the x-direction). The two other patterns were obtained with the X-rays directed parallel to the plane of the laminae, either along the capsule long axis (z) or perpendicular to this ( y). These two patterns were observed interchangeably in either of the xor y-directions depending on the specimen. The di¡raction patterns were analysed and interpreted taking into consideration the 3D electron microscope data of the egg case. The results con¢rm and extend previous ¢ndings from transmission electron microscopy and low-angle X-ray di¡raction and they suggest that there is only one major type of ordered collagen arrangement in the wall of the egg case.

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