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Sexual systems vary considerably among caridean shrimps and while most species are gonochoric, others are described as sequential protandric hermaphrodites or simultaneous hermaphrodites with an early male phase. At present, there is confusion about the sexual system exhibited by several species mostly because those studies attempting to reveal their sexual system draw inferences solely from the distribution of the sexes across size classes. Here we investigated the sexual system of the shrimp Hippolyte williamsi from Chile to determine if the species is protandric or gonochoric with sexual dimorphism (males smaller than females). Morphological identiWcation and size frequency distributions indicated that the population comprised small males, small immature females, and large mature females, which was conWrmed by dissections. No transitional individuals were found. Males maintained in the laboratory molted 1-8 times, and many grew up to reach sizes observed in only a small fraction of males in the Weld. No indication of sex change was recorded. Our results indicate that H. williamsi is a sexually dimorphic gonochoric species and emphasizes the importance of using several kinds of evidence (size measurements, growth experiments, morphological dissections, and histological studies) to reveal the sexual system of Hippolyte species. Whether the observed size dimorphism between males and females in many species of Hippolyte is expression of contrasting sexual and natural selection, and whether divergent sexual Wtness functions can contribute to the evolution of hermaphroditism remains to be revealed in future studies.

Sperm‐egg interaction in Rhynchocinetes typus was studied with the phase‐contrast and scanning electron microscopes. R typus spermatozoa present in the vas deferens have the shape of a round‐headed nail. After contact with seawater it is possible to observe the unfolding of the rays or stellate arms, giving the spermatozoon the appearance of an inverted umbrella. From the center of the flat face of the umbrella emerges a spike with longitudinal striations. Ovarian eggs and spermatozoa were mixed in vitro by agitating them for two minutes in Millipore‐filtered seawater. The first gamete contact was established by the spermatozoon through the tip of the spike, which exerted a lytic action on the egg envelopes. After the rigid spike was completely inside the egg, the rays became aligned parallel to each other and began to enter the eggs. Toward the final stages of ray entry, it was possible to observe fusion of the ray membranes with one another, and later the fusion process continued toward the tip of the radial spines. Concomitantly, the egg surface that surrounds the sperm swelled in a circular fashion and formed a fertilization cone. After the spermatozoon entry was complete, a scarlike mark appeared at the place on the egg surface through which penetration occurred. The whole penetration process was completed within 45‐60 minutes.

Rhynchocinetes typus spermatozoa obtained from the vas deferens have the shape of a round‐headed nail. The head measures 30 μm in diameter and 14 μm of height. At the center of the flat face of the head emerges a single rigid spike of 53 μm in length. Cross sections of this spike show that it has a wall of 0.4 μm in thickness and a core of 0.6 to 0.8 μm. The outer surface of the spike has a longitudinal striation. When the spermatozoa are placed in sea water it is possible to observe the unfolding of rays. The number of rays in different spermatozoa of the same individual varies from 9 to 13. Each ray is formed by a channel‐like sheath that contains a rigid rod that occupies about 1/3 the length of the ray. This rod has a transverse striation with a periodicity of 185A. The rays are bound among them by a thin membranous sheet that is highly folded in vas deferens spermatozoa. At the distal end of each ray there is a rigid spine of 50 μm in length. The nucleus is coplanar to the radial plane and it extends through the rays. The structure and ultrastructure of R typus spermatozoa depart from that reported for spermatozoa of other Caridea species.

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RESUMENEl presente estudio describe el desarrollo embrionario de la pintarroja común Schroederichthys chilensis, a través de observaciones de la morfología externa de la cápsula, morfología del embrión y mediciones del tiempo de gestación. Se recolectaron 60 cápsulas de huevos en la localidad de Chungungo (IV Región). Además se obtuvieron dos cápsulas desovadas por una hembra mantenida en cautiverio. Las cápsulas fueron descritas basándose en mediciones morfométricas, coloración, textura y presencia de las fisuras respiratorias. Para la determinación y descripción de la morfología embrionaria se utilizaron embriones extraídos de las cápsulas recolectadas. Para la determinación del tiempo de gestación se observaron continuamente 15 cápsulas con embriones vivos, a través de una ventana transparente en la pared de cada cápsula. Las cápsulas de huevos son rectangulares y tienen dos prolongaciones anteriores llamadas "filamentos del ovisaco" y dos posteriores llamadas "zarcillos". Las cápsulas recientemente desovadas son de coloración parda o verde opaco, textura parcialmente lisa y pegajosa y las fisuras respiratorias están selladas. Sin embargo, las cápsulas con embriones en estados avanzados son de coloración café oscura opaca, textura lisa y las fisuras respiratorias están abiertas. Se establecieron 6 estados de desarrollo embrionario en base a los siguientes caracteres diagnósticos: saco vitelino sin embrión, aperturas faríngeas, filamentos branquiales, diferenciación de las aletas desde el pliegue dorsal y ventral, espinas en la cola, hilera de espinas dorsales y pigmentación. El tiempo de gestación es de 211 días a una temperatura entre 11,1-15,8º C. PALABRAS CLAVES: Desarrollo, embriones, cápsulas de huevos, pintarroja, Chile. ABSTRACTThe present study describes the embrionary development of the redspotted shark, Schroederichthys chilensis, through observations of the external morphology of the eggs capsules, embryo morphology and measurement of gestation time. Sixty egg capsules were collected in the locality of Chungungo (IV Region, Chile). Two additional capsules were laid by a female kept in captivity. Eggs capsules were described based on morphometric measurements, coloration, texture and presence of respiratory fissures. For the determination and description of the embryonic morphology, embryos extracted from the collected capsules. For the determination of the gestation time 15 capsules with alive embryos were observed through a transparent window on the wall of each capsule. The eggs capsules are rectangular and they have two anterior prolongation called "filaments ovisac" and two posterior called "tendrils". The recently eggs capsules laid are brown or green opaque in coloration, partially smooth and sticky in texture and closed respiratory fissures. The eggs capsules with embryos in advanced stages are dark brown, flat texture and respiratory fissures open. Six stages of embrionary development were determined on the basis of the following diagnostic characters: viteline sac without embryo, pharyngea...

ABSTRACT. The present work identifies and quantifies the morphological alterations of scallop Argopecten purpuratus spermatozoa caused by long-term cryopreservation. Percentages of motility, fertilization and injured spermatozoa were quantified by optic microscopy and scanned electron microscopy. These parameters were evaluated in sperm without treatment (CTR), spermatozoa incubated in cryoprotective solution but not freezed (ICS) and freezed-thawed spermatozoa (FTS). Spermatozoa of ICS treatment remained motile longer than those of CTR, whereas those of FTS treatment were lowest. Morphology of the spermatozoa was affected in several ways by the freeze-thawing treatment; some had their head deformed or swollen, others had their cell membrane folded or broken; acrosome reaction; anomalous positions or absence of mitochondria as well as broken, stiff or loss of lineal structure of tail. CTR and ICS treatments had higher percentages of undamaged sperm (87.7% and 79.0% respectively), while FTS samples had 14.2% of undamaged sperm. The tail was the spermatic structure most commonly injured in FTS (77.0%), the percentage of sperm with head injury was 55.1% and with acrosome reaction was 28.7%, whereas middle piece was affected in 23.9% of sperm. Percentages of fertilization were 68.3%, 67.9% and 58.2% for CTR, ICS and FTS respectively, which were not significantly different. There was a higher correlation between injuries and motility than between injuries and fertilization success. Correlation between motility and fertilization was low (0.605 and 0.668 with motility at 5 and 30 min, respectively). Keywords: cryopreservation, Argopecten purpuratus, scallop, sperm, Chile. Alteraciones morfológicas en espermatozoides criopreservados de concha de abanicoArgopecten purpuratus RESUMEN. El presente trabajo identifica y cuantifica las alteraciones morfológicas en espermatozoides de concha de abanico A. purpuratus causadas por la criopreservación en nitrógeno líquido. Porcentajes de motilidad, fecundación de ovocitos frescos y espermatozoides lesionados (en cabeza, acrosoma, pieza media y flagelo) fueron determinados bajo microscopía óptica y electrónica de barrido. Estos parámetros fueron evaluados en un control sin tratamiento (CTR), espermatozoides incubados en solución crioprotectora pero sin congelamiento (ICS) y espermatozoides congelados-descongelados (FTS). Los espermatozoides del tratamiento ICS mostraron mayor motilidad que de CTR, mientras que la motilidad de los espermatozoides del tratamiento FTS fue la más baja. La morfología externa de los espermatozoides fue afectada de varias formas por el congelamiento-descongelamiento; cabeza deformada o hinchada, membrana celular plegada o rota, reacción acrosómica, anormal posición o ausencia de las mitocondrias, ruptura, rigidez o pérdida de la estructura lineal del flagelo. El CTR e ICS presentó los mayores porcentajes de espermatozoides ilesos (87,7% y 79,0% respectivamente), mientras que las muestras de FTS tuvieron 14,2% de espermatozoides ilesos. El flagelo fue la e...

RESUMEN: Estudios anteriores han demostrado que la aplicación de hormonas exógenas estimulan el proceso de maduración ovárica en camarones y cangrejos. Sin embargo, previamente es necesario conocer la dinámica del proceso de maduración ovárica y caracterizar los diferentes estados por los cuales atraviesan los ovocitos en su maduración. En este estudio se caracteriza la morfología y estructura fina de las etapas de la maduración del ovario y su dinámica en la langosta espinosa Jasus frontalis, utilizando microscopía de luz y electrónica de barrido. El ovario presenta una capa externa de tejido conjuntivo laxo y una gruesa pared muscular que origina tabiques musculares internos y extensiones filiformes. Las primeras atraviesan el ovario de pared a pared y las segundas se extienden hasta los folículos. Tanto en la pared muscular como en las extensiones se observaron numerosos vasos hemolinfáticos. En la región central de cada ovario y sostenido principalmente por tabiques musculares, se ubica un cordón germinativo ramificado, donde se encuentran ovogonias y ovocitos previtelogénicos. Se observó una zona de proliferación de este cordón en una zona cercana a la unión ovario-oviducto. Durante la maduración, los ovocitos se rodean de células foliculares, aumentan de tamaño y se desplazan hacia la periferia, donde forman folículos individuales. A medida que el ovario madura, hay un aumento progresivo de fibras colágenas que rodean a los folículos. La disposición entrecruzada de los haces musculares de la pared ovárica y extensiones, sugiere que éstos tienen una activa participación en el proceso de ovulación, concomitante con la acción de una colagenasa que hidrolisaría las fibras colágenas del folículo. A diferencia de las langostas Homaridae, esta especie ovula y desova casi simultáneamente, sin embargo la estructura ovárica en general es similar a las langostas de los géneros Homarus y Palinurus y camarones.