摘要:

Spermatozoa from the reproductive tubules and epididymis of the African lungfish,Protopterus aethiopicus, were examined by scanning, transmission and scanning‐transmission electron microscopy. The biflagellate nature of lungfish spermatozoa was confirmed as a general rule by examining large numbers of specimens in the scanning mode. All have two flagella with attached undulating membranes, a short middle piece and a large sperm head without condensation of the nucleus. The various portions of the sperm have been subjected to analysis of the X‐rays emitted upon electron bombardment, and the relative concentrations of several elements have been determi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04090.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The construction of foam nests by the Anura seems to be a habit that has evolved separately in all the main zoogeographical regions.Chiromantisis a large tree frog weighing up to 5.5 g which is restricted to the Ethiopian region. This genus comprises three species which are found in the three main African biomes from rain forest (C. rufescens), through woodland (C. xerampelina) to semi‐arid savannah (C. petersii). The female ofC. rufescensis shown in this study to construct her nest with the assistance of three males, and like the other two species, the nests are always fastened to objects over temporary water sources.Although the rain forest and savannah species are the same size the latter lays twice as many eggs as the former. Additionally it is shown that the eggs ofC. petersiiare only half the size ofC. rufescens.These facts can be correlated with the degree of permanence of the water source over which the nest is constructed.Features of the water economy and ecology are also describe

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04091.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

In the Serengeti, predator kills formed from 8 to 45 % of the carcasses that griffon vultures fed upon, the remaining carcasses coming from animals that had died from other causes. But since vultures obtained only very small amounts of food from predator kills, they had to rely for their food supply chiefly on the carcasses that were derived from other causes. In the Serengeti the large proportion of migratory ungulates prevent the mammalian predators from building up to a population size that can be responsible for a large proportion of ungulate mortality. It is estimated that the mammalian predators only take about one quarter of the potential food supply available for carnivores. The remaining ungulates die from various other causes, and so provide food for scavengers which varies in abundance and location with the seasons. This is a food supply which mammalian scavengers cannot easily use but griffon vultures, with their adaptations for gliding flight, are able to exploit it. These vultures therefore exploit a basically different food supply from predators and probably evolved as scavengers of migratory ungulate populations.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04092.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The annual testicular cycle of the tree sparrow(Passer montanus saturatus)has been studied by histochemical and biochemical techniques.The spermatogenetic cycle has two clearly defined peaks of activity. Throughout the winter the gonads are sexually regressed, but a recrudescence of spermatogenetic activity begins in the spring and the gonads rapidly develop into full breeding condition by April. In late April and early May a rapid testicular regression takes place as spermatogenetic activity terminates. Then, in July, a second seasonal spermatogenetic wave begins and gonads once again develop into a breeding condition. By August the testes have become fully regressed into their sexually quiescent post‐nuptial phase and remain this way until the following spring. The seasonal rehabilitation of the interstitial tissue, which is a characteristic part of many avian cycles, does not occur until this latter regressive phase.The seasonal fluctuations in thein vitroproduction of testosterone from A5‐pregnenolone‐16T shows the same annual bimodal pattern as the spermatogenetic cycle, being high at times when the seminiferous tubules are spermatogenetically active, and low during times of sexual quiescence. There is a close correlation between the level of testicular androgen synthesis and the seasonal fluctuations in the interstitial cell lipid cycle. Thus, testosterone synthesis builds up in the spring at a time when small sudanophilic lipid droplets are present in the interstitial Leydig cells, and reaches a peak at a time when this material is becoming rapidly depleted from the cell cytoplasm. During the first period of testicular regression, the Leydig cells become markedly sudanophilic, possibly as a result of the accumulation of precursor material at a time of low testosterone synthesis, then again become depleted of this material as secretory activity builds up once again.The possible interrelationship between the histochemical and biochemical cycles, and also the spermatogenetic cycle and the daily photoperiods, are disc

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04093.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

A species list of prey organisms of Rana temporaria in a blanket bog and adjacent man‐modified (mainly grassland) habitats is presented. From this it is concluded, in line with the findings of other authors, that this species is unselective and sedentary in its feeding habits. Argument is presented suggesting these habits are ideally suited to the needs of a bog‐land predator. It is further suggested that these habits tend to make R. temporaria a particularly effective predator of ground‐living predatory and parasitic in

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04094.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The ocular photophore ofBathothaumaemits light. The presumed photogenic tissue is cellular and contains a mass of highly organized crystalloids. One of its surface abuts against a fibrous system that probably acts as a light guide. The rest of the organ is surrounded by a pigment screen of modified iridophores.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04095.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The annual reproductive cycle has been investigated in the male pipistrelle batPipistrellus pipistrellus.Spermatogenesis occurs during summer and spermatozoa are produced in August and September. The seminiferous tubules then regress rapidly but sperm are stored throughout winter in the cauda epididymidis. Little change is apparent in the morphology of the Leydig cells throughout the year, and histochemical studies have revealed no seasonal differences in the occurrence of enzymes involved in steroidogenesis. The percentage yields of testosterone and androstenedione after incubation of testis and adrenal tissuesin vitrowith tritiated pregnenolone have been determined and measurements made of the concentration of these hormones in testes and whole blood. Although the highest levels of these androgens are synchronous with spermatogenesis, both continue to be produced by the testes during winter. Studies in castrated bats have confirmed these observations and indicate that the activity of the accessory reproductive organs during winter is dependent on testicular androgens. The testicular cycle of the pipistrelle is not thought to be complicated by adrenal androgenesis, or storage of androgens in the brown fat. The interrelationships between reproduction and hibernation in bats are discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04096.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The bursa epipharyngea of the Giant panda,Ailuropoda melanoleuca,is a saccular diverticulum (sacculus epipharyngeus) situated between pharynx roof and basis cranii. In the Ursidae the bursa comprises a pair of unequal‐sized diverticula having separate ostial communication with the epipharynx. Such dual type of bursa was recorded by Davis (1964) in theAiluropodaspecimen he systematically anatomized and was regarded as evidence indicating affinity with the Ursidae rather than with the Procyonidae. But in four additionalAiluropodaspecimens subsequently examined, and described herein, the ursid pattern of sacculus did not obtain. The significance of this difference in the anatomical findings is indicate

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04097.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The mammalian bursa epipharyngea commonly presents as an insignificant mucosal recess, not always recognisable macroscopically. In some mammalian forms, however, it is developed into an obtrusive diverticulum (sacculus epipharyngeus) extending caudally from the epipharynx between the cranial base and the pharynx roof. Among the Rhinocerotidae such an epipharyngeal saccule has been recorded forCeratotherium simum.Herein it is described for the first time inRhinoceros unicornis, Diceros bicornisandDidermocerus sumatrensis.Its tonsillar nature is established on morphological and histological grounds.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1974.tb04098.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY