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... The action of these organs can be made out by examining the anterior end of the living animal through a microscope while it is feeding. During the act of feeding the buccal tentacles are kept folded over one another. In this way these tentacles act as a sieve, allowing only the finer suspended parti ...
... The action of these organs can be made out by examining the anterior end of the living animal through a microscope while it is feeding. During the act of feeding the buccal tentacles are kept folded over one another. In this way these tentacles act as a sieve, allowing only the finer suspended parti ...
Novel modification of the tetrapod cardiovascular system in
... required in the development and maintenance of a single larger vessel than of multiple smaller ones carrying an equivalent volume of fluid. Thus functional considerations suggest that natural selection would favour the transition from paired to single arches, with the potential benefit of such a cha ...
... required in the development and maintenance of a single larger vessel than of multiple smaller ones carrying an equivalent volume of fluid. Thus functional considerations suggest that natural selection would favour the transition from paired to single arches, with the potential benefit of such a cha ...
The pharyngeal pouches and clefts
... crest [8]. The upper and lower lips of a lamprey are therefore not homologous to the upper and lower jaw of a jawed vertebrate. This change in position of the mouth appears to have occurred through changes in the area over which signalling molecules, such as Fgfs (Fibroblast growth factors) and Bmps ...
... crest [8]. The upper and lower lips of a lamprey are therefore not homologous to the upper and lower jaw of a jawed vertebrate. This change in position of the mouth appears to have occurred through changes in the area over which signalling molecules, such as Fgfs (Fibroblast growth factors) and Bmps ...
The pharyngeal pouches and clefts: Development, evolution
... crest [8]. The upper and lower lips of a lamprey are therefore not homologous to the upper and lower jaw of a jawed vertebrate. This change in position of the mouth appears to have occurred through changes in the area over which signalling molecules, such as Fgfs (Fibroblast growth factors) and Bmps ...
... crest [8]. The upper and lower lips of a lamprey are therefore not homologous to the upper and lower jaw of a jawed vertebrate. This change in position of the mouth appears to have occurred through changes in the area over which signalling molecules, such as Fgfs (Fibroblast growth factors) and Bmps ...
Lesson Overview
... development? The fusion of a sperm and egg cell is called fertilization. Key events in early development include gastrulation, which produces the three cell layers of the embryo, and neurulation, which leads to the formation of the nervous system. ...
... development? The fusion of a sperm and egg cell is called fertilization. Key events in early development include gastrulation, which produces the three cell layers of the embryo, and neurulation, which leads to the formation of the nervous system. ...
galathea-vol.03-pp_009-072
... The animals are bilaterally symmetrical. Small asymmetries are visible in some of the shells (Fig. 7), whereas those seen in the position of the anal opening, of the foot, and of the mouth in the preserved specimens are not constant in degree and perhaps may depend upon muscle contractions at the mo ...
... The animals are bilaterally symmetrical. Small asymmetries are visible in some of the shells (Fig. 7), whereas those seen in the position of the anal opening, of the foot, and of the mouth in the preserved specimens are not constant in degree and perhaps may depend upon muscle contractions at the mo ...
Cyclostome embryology and early evolutionary history of vertebrates
... mesoderm, they would be the premandibular mesoderm that arises secondarily, rostral to the mandibular mesoderm, in the late pharyngula stage. The more caudal head mesoderm, however, is only secondarily regionalized into several domains by epigenetic divisions caused by the surrounding structures, su ...
... mesoderm, they would be the premandibular mesoderm that arises secondarily, rostral to the mandibular mesoderm, in the late pharyngula stage. The more caudal head mesoderm, however, is only secondarily regionalized into several domains by epigenetic divisions caused by the surrounding structures, su ...
chitons - Biological Science - California State University, Fullerton
... still unhatched embryos. In comparison to early-stage larva, this latestage trochophore has already developed its foot so that it can crawl away; it has paired eyespots, and uncalcified shell precursors are visible on its dorsal surface. Photographs by the author. ...
... still unhatched embryos. In comparison to early-stage larva, this latestage trochophore has already developed its foot so that it can crawl away; it has paired eyespots, and uncalcified shell precursors are visible on its dorsal surface. Photographs by the author. ...
Six Specimens of Lyomeri in the British Museum (with notes on the
... An examination o i the skin shows that some papillae along the lateral line are still present, and confirms
... An examination o i the skin shows that some papillae along the lateral line are still present, and confirms
- studijní a informační středisko vfu brno
... They become arrested at the diplotene phase. A primary oocyte surrounded by a single layer of squamous follicular cells is known as a primordial follicle. The primordial follicles present the pool of quiescent follicles from which the female will recruit follicles for growth and ovulation for the re ...
... They become arrested at the diplotene phase. A primary oocyte surrounded by a single layer of squamous follicular cells is known as a primordial follicle. The primordial follicles present the pool of quiescent follicles from which the female will recruit follicles for growth and ovulation for the re ...
Segmented Worms
... systems were repeated in each segment. This repetition of body segments is called segmentation (also called metamerism). The advent of metamerism was significant because it made possible the evolution of much greater complexity in structure and ...
... systems were repeated in each segment. This repetition of body segments is called segmentation (also called metamerism). The advent of metamerism was significant because it made possible the evolution of much greater complexity in structure and ...
Chapter 47 - Animal Development
... of cellular respiration and protein synthesis by the egg cell ! With these rapid changes in metabolism, the egg is said to be activated ! The proteins and mRNAs needed for activation are already present in the egg ! The sperm nucleus merges with the egg nucleus and cell division begins ...
... of cellular respiration and protein synthesis by the egg cell ! With these rapid changes in metabolism, the egg is said to be activated ! The proteins and mRNAs needed for activation are already present in the egg ! The sperm nucleus merges with the egg nucleus and cell division begins ...
earthworm dissection
... outside the body as the cocoon moves forward over the body, picking up the eggs of one worm and the sperm of its mate. The pumping organs of the circulatory system are five aortic arches. Circulatory fluids travel from the arches through the ventral blood vessel to capillary beds in the body. The fl ...
... outside the body as the cocoon moves forward over the body, picking up the eggs of one worm and the sperm of its mate. The pumping organs of the circulatory system are five aortic arches. Circulatory fluids travel from the arches through the ventral blood vessel to capillary beds in the body. The fl ...
Structural types
... formation of mesoderm and coelom. The mesoderm is formed from endoderm in the form of hollow pouches which come to lie between ectoderm and endoderm; the cavities of the pouches form the coelom. Such animals are called enterocoelomate since the mesoderm and coelom arise from the gut. The other chara ...
... formation of mesoderm and coelom. The mesoderm is formed from endoderm in the form of hollow pouches which come to lie between ectoderm and endoderm; the cavities of the pouches form the coelom. Such animals are called enterocoelomate since the mesoderm and coelom arise from the gut. The other chara ...
Earthworm observation
... 1. Moisten a paper towel, and place it in a clean dissecting pan. Place the worm on the paper towel. You are working with a live animal. Handle it gently, and follow all lab instructions carefully. Watch the worm move, and notice which end leads. The worm’s leading end is its anterior end. Identify ...
... 1. Moisten a paper towel, and place it in a clean dissecting pan. Place the worm on the paper towel. You are working with a live animal. Handle it gently, and follow all lab instructions carefully. Watch the worm move, and notice which end leads. The worm’s leading end is its anterior end. Identify ...
Diverse Adaptations of an Ancestral Gill: A Common Evolutionary
... tubular tracheae, and spinnerets derive from modified epipods/gills of successive opisthosomal segments. The hypothesis that these structures derive from the opisthosomal book gills of aquatic chelicerates dates back to comparative anatomical studies of the late 19th century [5–8], but until now man ...
... tubular tracheae, and spinnerets derive from modified epipods/gills of successive opisthosomal segments. The hypothesis that these structures derive from the opisthosomal book gills of aquatic chelicerates dates back to comparative anatomical studies of the late 19th century [5–8], but until now man ...
The Development of the External Features of Xenopus lvis, based
... in length. It differs from fig. 9 only in the development of the extremities. The head is still broad and flattened (fig. 10 a). The hind leg has become longer and projects beyond the margin of the fin-fold. The knee is very clearly to be seen, and its joint is bent, as shown in fig. 10 a. The toes ...
... in length. It differs from fig. 9 only in the development of the extremities. The head is still broad and flattened (fig. 10 a). The hind leg has become longer and projects beyond the margin of the fin-fold. The knee is very clearly to be seen, and its joint is bent, as shown in fig. 10 a. The toes ...
Virtual Shark Lab - Teacher Site Home
... wastes and the maintenance of water balance; the other, the reproduction of species. However, due to their similar developmental origins and the sharing of common structures, they are usually considered as a single system. ...
... wastes and the maintenance of water balance; the other, the reproduction of species. However, due to their similar developmental origins and the sharing of common structures, they are usually considered as a single system. ...
Embryology, comparative anatomy, and congenital malformations of
... of the dorsal mesogastrium to form the greater omentum likely began with the evolution of jawed vertebrates. In reptiles and birds, the lungs are separated from the peritoneal (abdominal) cavity by an oblique septum, thus allowing for a more extensive respiratory system to develop. In mammals, this ...
... of the dorsal mesogastrium to form the greater omentum likely began with the evolution of jawed vertebrates. In reptiles and birds, the lungs are separated from the peritoneal (abdominal) cavity by an oblique septum, thus allowing for a more extensive respiratory system to develop. In mammals, this ...
Embryo Transfer as an Assisted Reproductive Technology in Farm
... there is a protective mechanism which prevents recognition of the foreign fetus by the mother of the other species [28]. Successful production of live interspecific chimeras between two murine species, Mus musculus and Mus caroli, has been reported [29]. Mus caroli ↔ Mus musculus chimeras thus appea ...
... there is a protective mechanism which prevents recognition of the foreign fetus by the mother of the other species [28]. Successful production of live interspecific chimeras between two murine species, Mus musculus and Mus caroli, has been reported [29]. Mus caroli ↔ Mus musculus chimeras thus appea ...
Earthworm Dissection – Ch 15
... body and pin it to the dissection pan using dissecting pins. Place one pin through the first segment and a second pin through the last segment. Pin the worm firmly to the dissection tray. Starting about one inch posterior to the clitellum, make a small slit with scissors and begin to cut upwards tow ...
... body and pin it to the dissection pan using dissecting pins. Place one pin through the first segment and a second pin through the last segment. Pin the worm firmly to the dissection tray. Starting about one inch posterior to the clitellum, make a small slit with scissors and begin to cut upwards tow ...
BIOLOGY 340 Comparative Embryology Laboratory Exercise 3
... head comes to be bent around and under the body. Ultimately it comes very close to touching the developing heart! You must keep this in mind as you examine the developing embryos. It is impossible to position all of the slices of the prepared embryo such that they always pass perpendicular to the lo ...
... head comes to be bent around and under the body. Ultimately it comes very close to touching the developing heart! You must keep this in mind as you examine the developing embryos. It is impossible to position all of the slices of the prepared embryo such that they always pass perpendicular to the lo ...
Word Document Lab 3B
... head comes to be bent around and under the body. Ultimately it comes very close to touching the developing heart! You must keep this in mind as you examine the developing embryos. It is impossible to position all of the slices of the prepared embryo such that they always pass perpendicular to the lo ...
... head comes to be bent around and under the body. Ultimately it comes very close to touching the developing heart! You must keep this in mind as you examine the developing embryos. It is impossible to position all of the slices of the prepared embryo such that they always pass perpendicular to the lo ...
Observation of Earthworms Name__________________ Block
... 1. Moisten a paper towel, and place it in a clean dissecting pan. Place the worm on the paper towel. You are working with a live animal. Handle it gently, and follow all lab instructions carefully. Watch the worm move, and notice which end leads. The worm’s leading end is its anterior end. Identify ...
... 1. Moisten a paper towel, and place it in a clean dissecting pan. Place the worm on the paper towel. You are working with a live animal. Handle it gently, and follow all lab instructions carefully. Watch the worm move, and notice which end leads. The worm’s leading end is its anterior end. Identify ...
Plates 41 to 56
... retractor muscles. Horizontal section. Anterior direction to the right. Microphotograph. Spec. IV. Fig. 150. Epithelium of the dorsal coelomic cavity with pigment granules. Microphotograph. Spec. 111. Fig. 151. Detail of transversal section showing the thin walls of the ventricle, the atrium, the pe ...
... retractor muscles. Horizontal section. Anterior direction to the right. Microphotograph. Spec. IV. Fig. 150. Epithelium of the dorsal coelomic cavity with pigment granules. Microphotograph. Spec. 111. Fig. 151. Detail of transversal section showing the thin walls of the ventricle, the atrium, the pe ...