摘要:

AbstractThe embryonic osteocranium of the elapid snake,Naja haje(Egyptian cobra) has been studied. The osteocranium of the 166‐mm embryo has been graphically reconstructed and described in detail. Those of younger and older embryos as well as the just‐hatched young have been also investigated. The membrane‐bones make their appearance before any sign of ossification in the cartilaginous cranium. The maxillary, palatine and pterygoid premordia have an earlier appearance than the other bony premordia.The fused premaxillae arise beneath the antero‐medial part of the solum nasi of the nasal capsules. They send dorsally the rudiment of the processus nasalis and posteriorly two small processes. The nasal develops as a protecting bony roof for the cartilaginous nasal capsule. It possesses a median descending portion which penetrates deeply between the capsules. The frontal arises at first over the fenestra olfactoria advehens and the planum antorbitale, then extends posterioly. Its median descending portion has not yet ossified. The prefrontal embraces the posterolateral surface of the nasal capsule. It is perforated by the foramen of the lacrymo‐nasal duct, the lacrymal bone is completely absent. The parietal is very long forming the incomplete roof and the side wall of the temporal region. It is quite apart from the frontal. The cranial roof between the two frontals and two parietals is bridged by connective tissue. Both the frontal and parietal bones form well developed lateral down‐growths. The postfrontal is present, lying just lateral to the anterior part of the descending process of the parietal, but the postorbital is completely lacking.There is only one temporal bone which is regarded as the supra‐temporal. This bone arises just lateral to the auditory capsule, its posterior part is intercalated between the quadrate and the capsule. The squamosal, tabular, jugal and quadratojugal are totally absent. The maxilla arises directly below the anterior half of the eye. It sends inwards a well developed palatal process. The rudiments of the maxillary teeth, including those of the poisonous fangs, have not yet been attached to the bone. The prevomer forms the medial wall and floor of the bony capsule which surrounds Jacobson's organ. It consists of a medial portion which extends nearly vertically and a ventral one which extends horizontally. The septomaxilla forms the lateral wall and a part of the floor of Jacobson's organ bony capsule. It possesses a very long posterior projection. The palatine arises medial to the maxilla, posteriorly it is about to touch the anterior tip of the pterygoid. The pterygoid is very long, occupying about half the total length of the palate. Both the palatine and pterygoid carry teeth which have not yet been completely attached to the bones. The ectopterygoid arises lateral to the hind extremity of the palatine and the anterior half of the pterygoid. The parasphenoid is a narrow elongated bone which arises in between the anterior halves of the trabeculae cranii. It is completely separate from the lateral down‐growths of the frontals and from the basisphenoid.Other than the cartilage‐bone, the articular, each ramus of the lower jaw is composed of the following membrane‐bones: dentary, splenial, angular, and the combined supra‐angular and prearticular. The fusion between the supra‐angular and prearticular takes place in late embryos.As regards the cartilage‐bones, the basioccipital ossifies perichondrally in the posterior part of the basal plate, behind the basicranial fenestra. The exoccipital ossifies in the occipital arch, and spreads medially forming a center in the posterior part of the tectum synoticum. The basisphenoid ossifies in the anterior region of the basal plate (including the crista sellaris) and the posterior ends of the trabeculae cranii. The basicranial fenestra is still present in its center. The supraoccipital arises from a pair of perichondral lamellae formed on the dorsal and ventral surfaces of the anterior part of the tectum synoticum. Laterally, on either side, it extends slightly in the roof of the auditory capsule, but this lateral part must not be considered as an epiotic since its independent ossification is not observed. The opisthotic arises from two perichondral lamellae on the outer and inner surfaces of the postero‐lateral part of the auditory capsule. It is quite separate from the exoccipital. The prootic ossifies perichondrally in the anterior portion of the auditory capsule, as far backwards as the anterior margin of the fenestra ovalis. The epipterygoid is completely lacking. The quadrate bone is formed by the perichondral ossification of the quadrate cartilage and the intercalare. The stapes and the shaft of the columella auris ossify perichondrally, but the processus dorsalis is still cartilaginous.The laterosphenoid bone is wedged between the auditory capsule and the basisphenoid, it is completely fused with the prootic. It is of double origin; its ventral part arises by the perichondral ossification of the laterosphenoid cartilage while its dorsal part arises without cartilaginous preformation. The articular arises perichondrally round the hind part of Meckel's cartilage, it is distinct from the combined supra‐angular and prearticular. No ossification

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00414.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn the present article, the median dorsal bones, bones of the upper jaw, circumorbital series and occipital ring of the skull of the adult Egyptian cobra,Naja hajehave been described in detail, and compared with those of the other snakes studied by the previous authors. The median dorsal bones of the cranium are the nasals, frontals, parietals, but not the premaxillae. The paired nasals are exceptionally elongated anteriorly to the extent that the premaxillae and their processus nasalis are completely hidden in a dorsal view. The paired frontals send lateral downgrowths through their whole length which unite together in the mid‐ventral line just dorsal to the parasphenoid. The fused parietals also send lateral downgrowths which articulate ventrally with the posterior part of the parasphenoid and the anterior part of the basisphenoid.The upper jaw is composed only of the premaxilla, maxilla and quadrate on either side. The fused premaxillae possess a processus nasalis, and ventrally they send backwards a palatal process. The maxilla carries two poisonous fangs and two solid small teeth. It is quite separate from the premaxilla, but connected with the palatine (through its palatal process), prefrontal and ectopterygoid. The length of the maxilla is reduced in comparison with that of the boids and colubrids.The incomplete bony orbital ring is formed only of the prefrontal, frontal and postfrontal. Thus the jugal, lacrymal and postorbital are completely lacking, and the parietal is excluded from the circumorbital series by the presence of the postfrontal. The prefrontal extends from the cranial roof to the upper jaw. It is firmly fixed dorsally with the antero‐lateral border of the frontal. Its ventral edge is firmly fixed to the dorsal surface of the maxilla and its palatal process. The antero‐dorsal edge of the postfrontal is connected with the postero‐lateral edge of the frontal, while its medial edge is in sutural contact with the parietal and its lateral downgrowth.The occipital ring consists of the four occipital bones; the basioccipital ventrally, the two exoccipitals laterally and dorsally, and the supra‐occipital dorsally. The sutures separating these bones from one another are distinct. The two exoccipitals articulate with each other dorsally above the foramen magnum, thus excluding the supraoccipital from this foramen. The occipital condyle is tripartite formed out of the basioccipital and the two exoccipitals. The exoccipital is completely fused, without any line of demarcation, with the opisthotic to form a compound bone which is called the ot

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00415.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn the present paper, the otic capsule, palate, temporal bones, lower jaw and hyoid apparatus of the skull of the adult Egyption cobra,Naja haje, have been described in detail, and compared with those of the previously studied ophidian species. The otic capsule is composed of the prootic, laterosphenoid and opisthotic. The fenestra ovalis interrupts the suture separating the prootic and the opisthotic part of the otoccipital. The laterosphenoid is a rather minute bone lying lateral to the center of the prootic, with which it is completely fused both above and below without any trace of sutures.The palate is composed of the premaxillae, maxillae, prevomers, septomaxillae, palatines, pterygoids, ectopterygoids, basisphenoid and parasphenoid. There is no actual contact between the two prevomers. Each prevomer is composed of a median vertical part and a lateral horizontal one. It is quite separate from the premaxillae, maxilla and palatine. The septomaxilla is wedged between the nasal dorsally, the premaxilla anteroventrally, and the prevomer postero‐ventrally. The palatine is connected posteriorly with the pterygoid and laterally (by means of an outer process) with the palatal process of the maxilla. It carries about seven teeth. The pterygoid is a very long bone, it is connected with the quadrate only by a ligament. The pterygoid is free from the brain‐case, and carries about fourteen teeth. The ectopterygoid connects the maxilla with the pterygoid. The epipterygoid is completely absent. The basisphenoid is completely fused anteriorly with the parasphenoid without any trace of a suture. The parasphenoid is firmly fixed above to the lateral downgrowths of the frontals, and suturally articulates postero‐laterally with the lateral downgrowths of the parietals.There is only one temporal bone on either side which is regarded as the supratemporal. Thus the squamosal and tabular are completely absent. This supratemporal holds the quadrate to the cranium.Each mandibular ramus is composed of four distinct bones which are the dentary, splenial, angular and a composite bone. This composite bone is the result of the complete fusion of the articular, prearticular and supra‐angular. The coronoid bone is completely lacking.The cartilaginous hyoid apparatus is composed of two very long ceratohyals which are fused anteriorly to a small hyoid

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00416.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe anatomy of the head is described for three species of syrphid larvae of differing feeding habits and the relation of the structure to the function is shown.The degree of adaptation of both the musculature and the skeletal parts of the cephalopharynx to the type of food which the larva partakes is discussed. The mouthparts are discussed in detail and the probable course by which the complex mandibular lobes of aquatic, filter‐feeding syrphid larvae were evolved, is pointed ou

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00417.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe distribution and seasonal variations in the numbers of mast cells in the brain of 27 hedgehogs (Erinaceus europaeus Lin.) were investigated. Mast cells are numerous in thalamus and are mostly found in close proximity to blood vessels. Mast cells are frequently found in pedunculus cerebellaris, and they are always seen in the ependymal cell layer of the 4th ventricle. It was shown that the number of mast cells in thalamus is increased during hibernation and that the brains of females contain more mast cells than those of males. The phsyiological role of the increase in the number of mast cells during hibernation is discussed.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00420.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractWhen testicular growth is induced in photosensitive white‐crowned sparrows (Zonotrichia leucophrys gambelii) by photoperiodic stimulation, there is an accompanying appearance of acetylcholinesterase‐containing cells in the pars distalis. Such cells do not appear in photorefractory birds subjected to long daily photoperiods; gonadal growth does not occur in these. To study further the function of these AChE‐containing cells, the activities of the thyroid gland, the adrenal cortex, and the gonads were inhibited or eliminated in photorefractory birds. No AChE cells appeared with the induction of increased TSH secretion with treatment of propylthiouracil and thiourea. Similarly adrenalectomy, treatment with metyrapone (2‐methyl‐1, 2‐di‐3‐pyridyl‐1‐propanone) as well as castration of photorefractory birds failed to cause the appearance of these cells. On the other hand, castration of photosensitive males and treatment with long days caused the development of AChE cells which, in comparison with the control, non‐castrated photostimulated males, were hyperplastic and hypertrophied. This supports our earlier suggestion that the AChE cells are gonadot

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00421.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn hynobiid urodele embryos there are three serially arranged muscles associated with the otic and occipital regions of the endocranium. These muscles are continuous posteriorly with the succession of trunk myomeres and most likely represent myotomic derivatives attributable to the third, fourth, and fifth metameres of the body. From front to back these muscles are designated: anterior basiotic, posterior basiotic, and occipital. A hitherto unknown cranial nerve is directed towards the posterior basiotic muscle in embryos ofHynobius retardatus. For this new somatic motor nerve the termnervus tenuisis proposed. Together with the glossopharyngeal nerve it constitutes the fourth cranionerval segment.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00422.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe examination of some Cytherid (or Cytheracean) ostracodes with the aid of the scanning electron microscope reveals that there is a high degree of variation in the structure and morphology of the normal pore system. The structural and morphologic polymorphism of these normal pores, the taxonomic importance of the variations, and their probable functional morphology are critically examined and discussed.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1970.tb00423.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY