Branchial Muscles Research Articles

Sarcoplasmic reticulum of striated muscle: localization of potential calcium binding sites.

Fish branchial muscle stained at a low pH with thorium dioxide shows localization of the stain over the sacroplasmic reticulum. Binding of the positively charged thorium micelles with dissociated acid groups of polyanions in this region suggests a possible mechanism for the storage and release of divalent cations such as calcium.

On the accessory respiratory organs of Ophicephalus punctatus (Bloch.) and Ophicephalus striatus (Bloch.)1

Summary 1 The accessory respiratory organs of 0. punctatus consist of:– 1 The supra-branchial chamber, 1 the respiratory ‘plates’, and 1 the respiratory epithelium. 2 The incomplete division of the supra-branchial chamber into an anterior and a posterior compartment, the action of the shutter (dendritic plate), the manner of communication between the two compartments and the communication with the pharynx by means of an inhalant aperture are described. 3 The respiratory plates have a bony medulla, cortex of connective tissue and a richly vascularized epithelium. 4 The respiratory nodules consists of connective tissue covered externally by a stratified epithelium. Mucous glands and taste-buds occur on them. Each nodule represents a modified gill lamella and its covering epithelium is derived partly from the wall of the pharynx and partly from the branchial epithelium. 5 The respiratory epithelium covering the ‘plates’ and ‘nodules’, and lining the supra-branchial chamber consists of vascular and non-vascular areas. Each vascular area is studded with ‘rosettes’ of papillae projecting from the epithelium. 6 The branchial muscles have become modified in several ways in order to suit the changeover from the aquatic to the aerial mode of respiration. In O. striatus the first, second and the fourth levators are well developed, run over the saccular part of the supra-branchial chamber and are responsible for its bellowing action. In O. punc-iatus the second and third levators have modified into the constrictor supra-branchi-alis which fans out on the wall of the posterior part of the supra-branchial chamber. The non-vascular part of the epithelium is in the form of irregular ‘lanes’ between the adjacent vascular areas. The presence of pilaster cells and the pattern of the vascular supply to the ‘rosette’ show that the vascular papillae of the respiratory epithelium of the supra-branchial chamber, the nodules and the plates have been derived from the gill lamellae. Each vascular ‘patch’ or ‘zone’ structurally corresponds to one primary gill lamella and each ‘rosette’ to several secondary gill lamellae.

Observations on the Branchial Crown of the Serpulidae (Annelida, Polychaeta)

1. This paper records various observations supplementing, and in some cases correcting previous accounts of the internal structure of the branchial crown in Pomatoceros triqueter, Serpula vermicularis, Hydroides norvegica, Vermiliopsis infundibulum, Salmacina incrustans, Protula intestinum, Spirorbis corrugatus, and Spirorbis militaris. 2. The muscles in the opercular peduncle of Pomatoceros are longitudinal. 3. A single layer of small longitudinal muscle-fibres, of unknown function, has been found on the abfrontal face of the internal branchial and internal peduncular nerves of most of these serpulids. 4. External branchial muscles are well developed in Pomatoceros, reduced in Serpula, Hydroides, Vermiliopsis, and Spirorbis militaris, and apparently absent in Protula and Spirorbis corrugatus. 5. The pinnules of Pomatoceros and Hydroides, like filaments and opercular peduncles, have a double innervation. 6. The internal skeleton of the serpulid crown consists of sheets and strands of connective tissue-fibres and, in the opercula, of a cartilage-like tissue with a ground substance giving the staining reactions of collagen. The serpulid branchial skeleton is compared with that of sabellids, and the chemical nature of these skeletons is discussed. 7. Extensions of the prostomial and peristomial cavities accompany the branchial blood-vessels into the base of the crown, but have no connexion with the cavities in the branches of the crown. The arrangement of the latter is described. The nature of all these cavities, whether coelomic or blastocoelic, is obscure. 8. The ‘palps’ of Pomatoceros, Serpula, Hydroides, and Vermiliopsis closely resemble pinnules. The blood-vessel and nerve of the ‘palp’ of Pomatoceros are branches of those in the adjacent filament. It is suggested that the serpulid ‘palp’ is a modified pinnule.

On the Development of the Hypobranchial, Branchial, and Laryngeal Muscles of Ceratodus. With a Note on the Development of the Quadrate and Epihyal

ABSTRACT As is well known, Wiedersheim stated that laryngeal muscles exist in Lepidosiren and Protopterus, but are absent in Cera- todus. He admitted, however, that the specimen investigated was badly preserved. In a recently published paper (1920) on the laryngeal muscles of Amphibia, I suggested that, possibly, they might be found in better specimens. Owing to the skill and perseverance of Dr. Bancroft I have come into possession of some well-preserved heads, and also of a series of embryos up to the stage of 30 mm. in length for purposes of investigation. The material also enabled me to examine the development of the hypobranchial and pharyngeal muscles, which, together with other structures, have been the subject of an elaborate memoir by Greil. In the description given by Semon of the development of Ceratodus the embryos were depicted in a series of stages numbered from 1 to 48, the last mentioned and oldest stage described being an embryo of 17-8 mm. Greil’s description is based on Semon’s stages, and also extended to stage 48. The embryos described in this paper had been fixed in formalin, and their lengths are given in millimetres. Their relation to Semon’s stages will be found in an appendix. A tabular statement of the synonyms of the names employed has also been appended.