摘要:

AbstractThe diet and feeding mechanism inCottus gobioandParenophrys bubalisare described, together with the morphology and histology of the alimentary tract. Both species are sluggish bottom dwelling, carnivorous fish, and are capable of catching and swallowing relatively large prey. The gut is fully differentiated into esophagus, stomach, intestine with pyloric ceca, and rectum. The liver is morphologically separate from the pancreas, and separate bile and pancreatic ducts open into the base of one of the pyloric ceca. The organisation of the gut is well suited to the fishes' mode of life, showing adaptations for taking large meals which may be at irregular intervals.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00540.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe early embryonic development ofPygoscelis adeliae, up to the stage with fused neutral folds, was investigated by means of serial sections and compared with the development of the chick (Gallus domesticus). The total incubation time in the penguin is about 35 days, compared with about 20 days in the chick (Herbert 1967). This superior rate of development in the chick is likewise recognized in the early period of development; for fusion of neural folds is achieved 45–49 hours after laying in the chick and 6–7 1/2 days incubation in the penguin. Furthermore the time of origin and shape of the neural tube, notochord and heart show recognizable differences in the two gen

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00541.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractTongue anlagen from which the anterior, posterior, right or left lateral halves had been extirpated generally regenerated completely within 15–30 days inRana catesbeianaandR. clamitans. Regeneration was most rapid and greatest in posterior and median regions. Removal of anterior‐posterior and left‐right middle thirds and of anterior, posterior, right or left dorsal or ventral quarter anlagen (R. catesbeiana) showed similar regenerative gradients. Regeneration never occurred when entire anlagen were removed.Extirpations of early and half‐developed lingual cornua were made in metamorphosing and young adultR. catesbeiana, R. clamitans R. palustrisandR. pipiens. Regeneration occurred where preoperative cornua did not exceed 1.5 mm, but never when they exceeded this length.It is concluded that anuran tongue anlagen, at the stages operated on, possess considerable reorganizing powers following partial extir

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00542.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractIn the present study the whole sample of 772 desert gerbils was collected from the semi‐arid areas in and around Jaipur (Rajasthan, India). The male exhibits active spermatogenesis and well maintained accessory reproductive organs at any time of the year. Reproductive organs of the male gerbil are briefly described.The vaginal and urinary openings are independent in the gerbil. There are four pairs of mammae.Follicular development takes place cyclically. Maximum atresia of follicles is noticed during metoestrus. A well developed Graafian follicle measures 590 μ across its widest diameter. The average diameter of the ovum is 65 μ.At the time of ovulation formation of stigma occurs which gives way to the ovum. The corpus luteum is formed from the remaining granulosa cells of the ovulated follicle. Fully formed corpus luteum of the cycle (during dioestrus) measures 740 μ. Maximum development of the corpus luteum is seen during late pregnancy (22–25 days) when it measures 1250 μ.During pregnancy large Graafian follicles are absent. After parturition the ovary shows corpora lutea of lactation.Histological changes in the uterus and vagina during the oestrous cycle of the gerbil are described. There is less proestrus distension of the uterus as compared with the rat. During oestrus the uterine endometrium hypertrophies and there are some degenerative changes in the epithelial lining. The changes in the vaginal epithelium are clear cut and are correlated with the ovarian activity. During proestrus proliferation of the epithelium occurs and at ‘heat period’ or oestrus the epithelium shows formation of the stratum corneum and the shedding of cornified cells. In the dioestrus the vaginal epithelium is heavily infiltrated by leucocytes.There are three peaks in the incidence of pregnancy rate, i.e., February to April, July, and September to November. Pregnancy rate is lowest during summer (May and June) and winter (December and January). Average monthly litter size shows almost similar changes.The average length of gestation period is 30 days. There is post‐partum heat in this animal. Formation of a vaginal plug is noticed following copulation.Litter size varies from 2–7. The average body weight of the new born young is 3.5 and 3.4 gm respectively for the male and the female. Weaning of the young is observed after about 20 days. Descent of the testes into the scrotal sacs occurs around day 28. Vagina opens afte

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00543.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe morphogeneesis of sound producing organs inGryllus bimaculatushas been studied in detail. Though the auxiliary structure of the sound producing organs are fully formed in the last nymphal instars the essential structure of the sound production, namely the file, appears only at the imaginal moult. The teeth of the file show variation in number between 135–165. All the teeth have similar structures. The muscle 107a plays an important role in the sound production and is present only in the mal

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00544.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractA detailed account of the structure of the axillary sclerites of the fore and the hind wings is given. In the fore wing the first axillary is less developed than the second. In the hind wing the second axillary is less developed than the first. The inverse relative development of the first and the second axillary sclerites in the fore and the hind wings has arisen in response to the different type of role they have to play in the two wings. The structure of axillaries reveals that their modifications are intimately associated with the efficient mechanism of flexion and extension of the wings.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00545.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe vas deferens and epididymis of the tortoise,Testudo hermanni, contained very large amounts of noradrenaline but no certain amounts of adrenaline and dopamine. Small polymorf cells exhibiting a fluorescence typical of catecholamines were present in the tissues. It is concluded that most of the noradrenaline present in these organs is confined to the small cells. Their origin and possible function is discussed, and it is suggested that they may have the same function as the short adrenergic neurons present in the male genital tract of mammals.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1969.tb00546.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY