Pelvic Fin Bud Research Articles

Heterochronic development of pelvic fins in zebrafish: possible involvement of temporal regulation of pitx1 expression.

Anterior and posterior paired appendages of vertebrates are notable examples of heterochrony in the relative timing of their development. In teleosts, posterior paired appendages (pelvic fin buds) emerge much later than their anterior paired appendages (pectoral fin buds). Pelvic fin buds of zebrafish (Danio rerio) appear at 3weeks post-fertilization (wpf) during the larva-to-juvenile transition (metamorphosis), whereas pectoral fin buds arise from the lateral plate mesoderm on the yolk surface at the embryonic stage. Here we explored the mechanism by which presumptive pelvic fin cells maintain their fate, which is determined at the embryonic stage, until the onset of metamorphosis. Expression analysis revealed that transcripts of pitx1, one of the key factors for the development of posterior paired appendages, became briefly detectable in the posterior lateral plate mesoderm at early embryonic stages. Further analysis indicated that the pelvic fin-specific pitx1 enhancer was in the poised state at the larval stage and is activated at the juvenile stage. We discuss the implications of these findings for the heterochronic development of pelvic fin buds.

Early ontogeny of tetra Markiana nigripinnis (Characiformes: Characidae)

Abstract The early development of Markiana nigripinnis is described by morphological characters, pigmentation, and morphometry. Larvae were obtained through semi-natural breeding, collected, fixed, and identified according to their development. Eighty individuals with standard lengths ranging from 3.1 to 24.3 mm were analyzed. Larvae are poorly developed at hatching, with a relatively large yolk sac and finfold. At the preflexion stage, the eyes are pigmented, the mouth and anus are functional, the yolk is completely absorbed, and the pectoral fin bud emerges. At flexion, the first rays of the caudal, anal, and dorsal fins become evident. The pelvic fin bud emerges only at the postflexion stage, in addition to the complete absorption of the finfold. Pigmentation is distributed throughout the body, with a greater concentration on the top of the head, around the mouth, and at the base of the caudal fin. The myomere total number ranged from 34 to 49 (16–23 preanal, and 18–27 postanal). Juveniles show morphological characteristics like adults. The fins ray number are pectoral: 11–13, pelvic: 5–7, dorsal: 8–11, caudal: 16–27, and anal 30–47. The morphometric relationships reveal variations in growth along the early ontogeny of the species.

Phenotypic study for embryonic and larval development of common carp (Cyprinus carpio L., 1758)

The early development of common carp (Cyprinus carpio L., 1758) was studied from fertilizing until juvenile stage. The series developmental staging was done using morphological characteristics. Results identified eight main periods of embryogenesis: zygote, morula, blastula, gastrula, neurella, segmentation, pharyngula and hatching period. Results also identified and described nine larval development stages: hatching larva stage, rudimentary - pectoral fin and gill arch stage, melanoid-eye with gas bladder emergence stage, one chamber gas bladder with yolk absorption stage, two chamber gas bladder stage, pelvic fin bud with dorsal fin formation stage, anal-caudal and pelvic fin formation stage, squamation stage and juvenile stage. Hatching occurred at 38h after egg fertilization. The fertilized egg was spherical, yellowish, transparent and 2.5 mm in diameter. The transition from larva to juvenile occurred in 30 days.

Localization of β-Catenin and Islet in the Pelvic Fin Field in Zebrafish.

In zebrafish, pelvic fin buds appear at 3 weeks post fertilization (wpf) during the larval to juvenile transition (metamorphosis), but their fate is already determined during embryogenesis. Thus, presumptive pelvic fin cells appear to memorize their positional information for three weeks, but no factors expressed in the pelvic fin field from the embryonic to the metamorphic stages have been identified. In mice, Islet1 is proposed to promote nuclear accumulation of β-catenin in the hindlimb field, which leads to the initiation of hindlimb bud outgrowth through activation of the Wnt/βcatenin pathway. Here, we examined the distribution of β-catenin and islet proteins in the pelvic fin field of zebrafish from the embryonic to the metamorphic stages. We found that transcripts of islet2a, but not islet1, are detected in the posterior lateral plate mesoderm, including the presumptive pelvic fin field, at the embryonic stage as well as in the pelvic fin bud at the metamorphic stage. Immunolocalization revealed that β-catenin and islet proteins, which are synthesized during the embryonic stage, remain in the cytoplasm of the presumptive pelvic fin cells during the larval stage, and are then translocated into the nuclei of the pelvic fin bud at the metamorphic stage. We propose that cytoplasmic localization of these proteins in the presumptive pelvic fin cells that remained during the larval stage may underlie the mechanism by which pelvic fin cells memorize their positional information from the embryonic stage to the metamorphic stage.

Genetical identification and morphological description of the larvae and juveniles of Porocottus leptosomus (Pisces: Cottidae) from Korea

The larvae and juveniles of Porocottus leptosomus belonging to the family Cottidae were collected (n = 95, 3.9–16.5 mm in body length, BL) from Busan, Korea, in March 2015. The larvae and juvenile were identified using DNA barcoding as P. leptosomus, and their morphological description was presented in detail. The yolk-sac larvae (3.9–5.6 mm BL) body was slightly compressed, the head was large, the eye was round and large, and the anus was before the middle of the body. The preflexion larvae (5.2–10.0 mm BL) body length drastically increased; caudal fin rays began to occur. The flexion larvae (9.4–11.8 mm BL) notochord flexion started; dorsal, pectoral, and anal fin rays began to occur; pelvic fin buds are seen; they possessed a pair of parietal spine; and a pair of supraocular cirri was first to develop. At 12 mm BL, the notochord was completely flexed. The larva stage (3.9–12.6 mm SL) had the stellate melanophores in the head, isthmus, gut, and tail (along to the ventral midline). During the juvenile stage (11.4–16.5 mm BL), melanophores covered the head and began to form five black bands on the side of the body. The larvae of P. leptosomus spent pelagic life, but moved to the bottom during the juvenile stage. The larvae and juveniles of P. leptosomus differ from other cottid larval fishes by body shape, melanophore head pattern, and spine development. P. leptosomus can be distinguished from Porocottus allisi by morphological development and the occurrence of larval fish: preopercular spine development, melanophore pattern, and caudal fin development.

Development of the lateral plate mesoderm in medaka Oryzias latipes and Nile tilapia Oreochromis niloticus: insight into the diversification of pelvic fin position.

The position of the pelvic fins among teleost fishes has tended to shift rostrally during evolution. This positional shift seems to have led to the diversification of feeding behavior and allowed adaptation to new environments. To understand the developmental basis of this shift in pelvic fin position among teleosts, we investigated the embryonic development of the lateral plate mesoderm, which gives rise to the pelvic fins, at histological levels in the medaka Oryzias latipes (abdominal pelvic fins) and Nile tilapia Oreochromis niloticus (thoracic pelvic fins). Our histological analyses revealed that the lateral plate mesodermal cells expand not only ventrally but also rostrally to cover the yolk during embryogenesis of both medaka and Nile tilapia. In medaka, we also found that the lateral plate mesoderm completely covered the yolk prior to the initiation of the pelvic fin buds, whereas in Nile tilapia the pelvic fin buds appeared in the body wall from the lateral plate mesoderm at the thoracic level when the lateral plate mesodermal cells only covered one-third of the yolk. We discuss the relevance of such differences in the rate of the lateral plate mesoderm expansion on the yolk surface and the position of the pelvic fins.

Early development stages of the catfishLophiosilurus alexandriSteindachner, 1877 (Pisces: Pseudopimelodidae) from the São Francisco River basin, Brazil

Summary Lophiosilurus alexandri reproduces in captivity, has a high commercial value in Brazil and carries great potential for aquaculture. Research was carried out on L. alexandri larvae from days 1 to 30 post-hatch (DPH). Based on descriptions in the literature four developmental stages were observed using anatomic, histological and statistical techniques to provide useful data for the taxonomy, aquaculture and conservation of this species. In the yolk sac stage (1–2 DPH) the larvae presented myomeres (pre 17–23 and post anal 25–32) evident along the body, open mouth, the beginning of eye pigmentation and intestine with simple prismatic epithelium. The preflexion stage (3–4 DPH) was characterized by onset of body pigmentation and appearance of the pectoral fin bud. The oesophagus, stomach and intestine presented a folded mucosa. The flexion stage (5–7 DPH) was characterized by a flexion of the notochord, the chondrogenesis of the neural arches, formation of the dorsal and anal fins (11 rays) and appearance of the pelvic fin bud. In the postflexion stage (8–30 DPH) the formation of pelvic fin rays (6 rays) occurred along with the development of three different stomach regions. Except for the variables related to the yolk sac, all other studied variables presented significant differences between developmental stages.

Description of Atherinella brasiliensis (Quoy & Gaimard, 1825) (Atheriniformes: Atherinopsidae) larvae from the Jaguaribe River estuary, Itamaracá island, Northeastern Brazil

The present study describes the external morphology and morphometry of the initial development of Atherinella brasiliensis, and contributes toward broadening knowledge on its biology. A total of 88 larvae and 14 juveniles were used to characterize the morphological development and analyze body proportions. Fish with standard lengths (SL) from 1.4 to 77 mm were used in the study. Larvae hatch at an average of 1.4 mm SL. In the preflexion stage, the larval body is enveloped by a finfold, which begins behind the head. Pectoral fins are the first to be formed and preflexion larvae have four characteristic dendritic chromatophores on the head. The flexion stage begins at an average of 4.4 mm SL; dorsal and anal fins already exhibit pterygiophores and a terminal, somewhat up-turned mouth. At 6.8 mm SL, the flexion stage ends. In the postflexion stage, larvae present greater ossification of the dorsal and anal fin rays, exhibit pelvic fin buds and a darkening of lateral pigmentation. At an average of 8.8 mm SL, head pigmentation intensifies and pelvic fins exhibit conspicuous ossifying rays. Larvae at 11.8 mm SL have all fins formed; the second dorsal fin is the last to be formed at an insertion point posterior to the anal fin. The juvenile period begins at approximately 12 mm SL. At this stage, A. brasiliensis has an anal fin located at the median portion of the body and the posterior end of pectorals surpasses the origin of pelvic fins, which are located at the midpoint between the pectoral and anal fins. Scales are present on the dorsal-lateral region behind the head. The morphological features of A. brasiliensis herein described allow an adequate identification of its larvae and differentiate them from hemiramphid and other atheriniform larvae, thus broadening knowledge on the larval biology of the species.

Description of Larval Cynoglossus Zanzibarensis (Teleostei: Cynoglossidae) from the Tsitsikamma Coast, South Africa

The early development and the temporal distribution of Cynoglossus zanzibarensis larvae are described, based on specimens collected along the Tsitsikamma coast, South Africa. The yolk sac is evident in larvae of up to 3.4 mm body length (BL). There are 46–57 (6−9 + 37−50) myomeres and the gut extends to 37, 36 and 31% BL in preflexion, flexion and postflexion larvae respectively. Flexion is initiated by 5.6 mm BL and is complete in all larvae >7.8 mm BL. Two elongate dorsal fin rays are visible by 3.5 mm BL, and a single medial pelvic fin bud appears by 6.2 mm BL. Eye migration is initiated in larvae >7.0 mm BL and complete by 11.6 mm BL. Pigment is concentrated over the ventral and lateral gut area, as well as along the dorsal and ventral trunk and tail surfaces. Lateral tail pigment becomes heavier in postflexion larvae. The larvae of C. zanzibarensis are compared with previously described tonguefish species, including the congeneric C. capensis, which has fewer dorsal and anal fin rays (D103–110, A81–88 compared with D116–124, A92–103), 2–4 elongate dorsal rays compared with 2 and a larger size at flexion (9.9 mm BL compared with 6.6 mm BL).

Larvae of Enchelyurus ater (Günther, 1877) and E. kraussi (Klunzinger, 1871) (Pisces: Blenniidae: Omobranchini)

The omobranchinin blenniid, Enchelyurus ater, ranges across the islands of the south Pacific Ocean, and E. kraussi ranges from the Red Sea to the Mariana Islands and eastern Australia. The planktonic larvae of these blennies were identified by establishing developmental series up to large larvae identifiable to species using morphological and meristic characters and geographic location. Larvae of both species are similar in appearance, hatch at about 1.5-2.5 mm length, and undergo notochord flexion at about 4.5-5.5 mm. Enchelyurus ater probably is near 12 mm, and E. kraussi probably nearer 15 mm, at settlement from the plankton. Larvae of both species have a rounded head, a short, coiled gut, an elongate, compressed tail, and about 34 myomeres. Small spines are present on the posterior preopercular margin at, or soon after, hatching. The spine at the preopercular angle becomes largest, reaching about 25% of head length in the postflexion stage. First the pectoral-fin rays, then principal caudal-fin rays, dorsal- and anal-fin anlagen, and pelvic-fin buds begin to form during the preflexion stage. All principal caudal rays are present by the end of the flexion stage. Pelvic-fin rays and all segmented dorsal- and anal-fin rays are present by mid-postflexion stage. Dorsal-fin spines and procurrent caudal-fin rays form during the postflexion stage. Larvae of both species initially are pigmented dorsally on the head and gut, posteriorly on the ventral margin of the tail, and on the mesial surface of the pectoral-fin base. Pigmentation gradually increases on the head and gut in both and on the pectoral fin in E. kraussi, and decreases on the ventral margin of the tail in both. Enchelyurus ater, E. kraussi, and the Hawaiian endemic, E. brunneolus, are a monophyletic group with unknown sister-species relationships. Larval characters suggest the hypothesis that E. ater is the sister species to E. brunneolus, and E. kraussi is the sister species to the other two.

Developmental Characteristics of a Freshwater Goby, Micropercops swinhonis, from Korea

The embryonic and larval development of a freshwater goby, Micropercops swinhonis (Odontobutidae; Gobioidei), from Korea are described. One female spawned several times from mid-April to early July. About 100 to 500 eggs per batch were laid on the under surface of the nest guarded by a male. Eggs hatched 12 days after spawning. Larvae, about 3.7 mm in total length (TL) just after hatching, passed the exogenous feeding larval stage, and reached the juvenile stage of about 16 mm TL in about one month. The developmental process of M. swinhonis is quite different from that of the fluvial Odontobutis of the same family, which skips the exogenous feeding larval stage, but is rather similar to that of amphidromous Gobiidae. On the other hand, the left and right pelvic fin buds of M. swinhonis appear distant from each other as in Odontobutis, rather than Gobiidae.

The evolution of paired appendages in vertebrates: T-box genes in the zebrafish.

The presence of two sets of paired appendages is one of the defining features of jawed vertebrates. We are interested in identifying genetic systems that could have been responsible for the origin of the first set of such appendages, for their subsequent duplication at a different axial level, and/or for the generation of their distinct identities. It has been hypothesized that four genes of the T-box gene family (Tbx2-Tbx5) played important roles in the course of vertebrate limb evolution. To test this idea, we characterized the orthologs of tetrapod limb-expressed T-box genes from a teleost, Danio rerio. Here we report isolation of three of these genes, tbx2, tbx4, and tbx5. We found that their expression patterns are remarkably similar to those of their tetrapod counterparts. In particular, expression of tbx5 and tbx4 is restricted to pectoral and pelvic fin buds, respectively, while tbx2 can be detected at the anterior and posterior margins of the outgrowing fin buds. This, in combination with conserved expression patterns in other tissues, suggests that the last common ancestor of teleosts and tetrapods possessed all four of these limb-expressed T-box genes (Tbx2-Tbx5), and that these genes had already acquired, and have subsequently maintained, their gene-specific functions. Furthermore, this evidence provides molecular support for the notion that teleost pectoral and pelvic fins and tetrapod fore- and hindlimbs, respectively, are homologous structures, as suggested by comparative morphological analyses.

Differential expression of Tbx4 and Tbx5 in Zebrafish Fin buds

In here we report the identification of two new members of the T-box gene family, zf-tbx5 and zf-tbx4, from the Zebrafish, Danio rerio. The amino acid sequences within the T-box domain share high homology with the mouse, chick, and newt orthologs. Whole mount in situ hybridization revealed specific expression of these genes in the eye and Fin buds. zf-tbx5 expression is restricted to the pectoral Fin bud, whilst zf-tbx4 transcripts are confined in the pelvic Fin bud. These results reveal the conserved expression pattern of Tbx5 and Tbx4 during appendage development in all animal species studied to date.

The fine structure of the developing pelvic fin dermal skeleton in the trout Salmo gairdneri

The morphogenetic and ultrastructural features of the dermal skeleton in the pelvic fin bud of a teleost, the rainbow trout Salmo gairdneri, have been examined by light and electron microscopy. The principal structural components observed are lepidotrichia and actinotrichia. Lepidotrichia consist of two parallel and symmetrical bony demirays that form jointed segments within the fin. The demirays calcify in a proximodistal direction within the extracellular collagen network of the basal lamella belonging to the epidermal-dermal interface of the fin. Needle- and plate-like particles of a solid mineral phase appear to be associated with the collagen fibrils and with a fine, granular, interfibrillar material central to the demirays. Cellular processes and membrane-bound vesicles are absent from the regions of calcification. During fin growth, the bony, acellular lepidotrichia are separated from the epidermal-dermal interface by infiltrating mesenchymal cells in proximal fin regions; in distal areas, the lepidotrichia remain within the basal lamella. The actinotrichia are extensive unmineralized rods of elastoidin that occupy the distal margin of the fin and precede the differentiation of lepidotrichia. Once the lepidotrichia form, actinotrichia lie preferentially between their demirays. In some instances, structural interactions are suggested between actinotrichia and lepidotrichia. Considerations of embryologic and structural features of fin components fail to support the hypothesis that individual segments of lepidotrichia are modified scales in all fish.

Mitotic activity in the pseudoapical ridge of the trout pelvic fin bud, Salmo gairdneri

AbstractA radioautographic study of the pseudoapical epidermal ridge, after tritiated thymidine labelling, shows that basal cells do not incorporate this precursor to DNA synthesis. The results conform with the low mitotic activity of this structure after vinblastine treatment, and point to a special metabolism of these cells, probably associated with their involvement in actinotrichial development.

Morphological Changes during the Larval Development of the Cutlips Minnow, Exoglossum maxillingua

Abstract Larval development of the cutlips minnow, Exoglossum maxillingua, is briefly described from 90 specimens reared from eggs to identifiable juveniles. Total lengths (TL) of larvae ranged from 5.4 to 16.1 mm. Juveniles may be as small as 14.5 mm. During early larval development there is a brief increase in proportional measurements of head, eye, and predorsal lengths as compared to TL. This upward trend ends abruptly. The ratio of standard length to TL decreases sharply until the larva reaches approximately 15 mm TL. To separate E. maxillingua larvae in early developmental phases from larvae of commonly sympatric minnow species several characters can be used, including size, pigment pattern, number of preanal myomeres, and morphometry. After formation of the pelvic fin buds, the cutlips minnow larva is easily identified by the presence of a frenum, absent in other sympatric minnows, during the same developmental phase, except daces of the genus Rhinichthys. It differs from the daces in the position ...

Scanning electron microscope study of the developing trout pelvic fin bud.

The growth of the pelvic fin bud has been studied with the SEM along with the characteristics of the pseudoapical epidermal ridge which occupies the free margin of the bud. SEM revealed fluffy protuberances in many of the epidermal cells, distinguishing the fin bud territory from adjacent areas. When the pseudoapical ridge appears, all the cells show this feature but their relative number decreases and these cells, termed the "tassel cells," are finally restricted to the base of the fin bud. This particular surface structure of the superficial cells may be unique to the fish, since it has not been heretofore reported in SEM studies of tetrapod limb bud.

The Fine Structure of the Early Pelvic Fin Bud of the TroutsSalmo gairdneriandS. trutta fario

The three components of the developing pelvic fin bud of the trout Salmo, namely the epidermis, the mesenchyme and the epidermal-mesenchymal interface have been studied with the electron microscope. The results suggest that the columnar cells of the pseudoapical ridge which forms a fold, could contribute to the initiation of the first actinotrichial deposits. We also report the alterations of the epidermal-mesenchymal interface, most obvious in the subepidermal space of the prominent pseudoapical ridge. We finally describe the features of both kind of mesenchyme. In each case, the present data are discussed against the background of the developing tetrapod limb bud literature.

Initiation of the actinotrichial development in the early fin bud of the fish, Salmo.

Ultrastructural analysis of initial development of actinotrichia, the skeleton anlage of the pelvic fin buds, was performed on the rainbow trout, Salmo gairdneri. It shows that the first actinotrichial rudiments appear in the subepidermal space of the pseudoapical cap. No mesenchymal cell bodies or their filopods are present. Hyaloplasmic protrusions of the basal epidermal cells are seen in the subepidermal space, limited by a dermoepidermal boundary reduced to a discontinuous thin adepidermal lamina without a collagenous layer. These morphological data suggest that the epidermal pseudoapical cap probably initiates the development of actinotrichia. Later, mesenchymal cells invade the subepidermal space and are probably involved in the further growth of actinotrichia.

Les premiers stades de la formation de I’ébauche de nageoire pelvienne de Truite(Salmo farioetSalmo gairdneri): III—Capacités de régulation

ABSTRACTThe first stages of genesis of the pelvic fin aniage in the trout (Salmo fario and Salmo gairdneri). III. Regulation capacitiesIn S. fario and S. gairdneri, microsurgical excisions of parts of pelvic fin-buds showed the important regulation capacities of the fin anlage. At the stages studied, a complete unilateral excision is generally not followed by a regulatory response. On the contrary, a unilateral partial excision performed at the same developmental stages is followed by a regulatory response. Bilateral excisions of the fin-buds, performed at earlier developmental stages than unilateral ones (and at a slightly different level for mesoderm) are followed by regulation.The results are discussed in this article. It appears that the mesoderm is a determining factor in the development of the fin-buds; the epidermis does not appear influential -at least in the first stages of regulation.We noticed a higher percentage of regulation in S. gairdneri than in S. fario’, the results obtained are analysed with regard to histoenzymological data.