摘要:

AbstractThe mature spermatozoon ofSpadella cephalopterabelongs to the filiform type. At the front end it contains a membraneous cap, which may be an acrosomal structure, and some beaded sacs. A crystal structure is found in these sacs in spermatid stages. Near this front end there is a centriolar structure. A very elongated mitochondrial derivative runs through most of the sperm. In the central half of the sperm there is a structure composed of some longitudinal sacs lying alongside the axonema. The nucleus is situated in the hind end, just in front of a free flagellum. The spermatozoon is highly unique, but to some extent it agrees with spermatozoa found among arthropodes and gastropodes.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1972.tb00576.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe incidence of limb loss and regeneration in two species of benthic Crustacea, the king crabParalithodes camtschatica, an anomuran, and the tanner crabChionoecoetes bairdi, a brachyuran, is surveyed in populations from the Bering Sea. 29.4 % of young juvenileP. camtschaticaand 14.8 % of adults had lost at least one limb. The overall incidence of limb loss inC. bairdiwas 38.8 %, with female adults less prone to damage than males and juveniles.Limb loss increases in frequency in more posterior limbs. Right hand limbs are lost more often than left in both species. This “right handedness” appears to be widespread in crabs and may be due to the greater vulnerability of leading limbs.The frequency distribution of limb regenerate lengths in a population of young juveniles suggests that at least four instars must be passed before limb symmetry is resto

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1972.tb00577.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe development of the olfactory rosette in parr, smolt and adult sea trout is investigated by means of different fixation and staining techniques. The rosette consists of primary laminae which are folded in four types of secondary laminae. These are here called initial, cuneiform, filiform and fungiform laminae. At least initially secondary folding seems to be an interplay between a blood capillary and the sensory epithelium external to it. The ecological adaptations of folded olfactory organs are discussed.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1972.tb00578.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe site of localization and concentration of ascorbic acid (AA) in a number of tissues of the pigeon were studied by a modified histochemical method coupled with cytophotoelectrometric determinations.It was evident from the data that significant variations were found in AA concentrations of different tissues of the pigeon. The brain possessed the highest content of AA/cell. The liver, ovary, pancreatic acini, kidney, adrenal and testis followed in order, whereas, the pancreatic islet region was the poorest in AA.On the basis of the synchronization of the high AA content of these tissues with their well known high level of metabolic activity, it is suggested that AA participates in the metabolic turnover by serving as an electron donor via the formation of its free radical.Considering the fact that these organs are very rich in ascorbic acid, there is also a possibility for the biosynthesis of AA in tissues like the liver and kidney of the pigeon as in other bird species. The need for further work in this direction is stressed.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1972.tb00579.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY