摘要:

AbstractThe anatomy and histology of the cloaca and spermatheca of 13 female smooth newts (Triturus vulgaris) were studied by light microscopy. The cloaca consists of a short, anterior tube (which receives the oviducts), which opens into a larger, more posterior chamber. The spermatheca, which is the only gland in the cloaca, consists of a mass of exocrine, acinar tubules which empty individually and dorsolaterally into the posterior part of the cloacal tube and all but the most posterior part of the cloacal chamber. Stored sperm are most abundant in the spermathecal tubules during the peak of the breeding season (in May and June); during their period of storage, the sperm do not appear to make intimate contact with the epithelial cells lining the spermathecal tubules. Longterm storage of viable sperm from one breeding season to the next is probably absent in the smooth newt. Sperm storage by and multiple insemination of females both occur in this species and are necessary preconditions for competition between the sperm of different males for the fertilization of eggs. However, sperm competition has not been demonstrated in the smooth newt.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00902.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of social environment on the proctodaeal glands of maleMicrotus agrestisL. was assessed by examining a number of physical parameters of the glands, as well as of the testes and of the blood, following a range of socialisation treatments. Social isolation depresses glandular development; vole odour from the stock room does not restore gland size. Socialisation with members of the opposite sex restores gland size, but replacement of females twice a week is less effective than constancy of partner. The glands respond to the level of blood testosterone, but glandular development appears to be heavily influenced by other factors.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00903.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe adrenocortical homolog (AH) was identified in the reed‐fish (Calamoichthys calabaricusSmith) using histochemistry for the enzyme δ5‐3β‐hydroxysteroid dehydrogenase (3β‐HSD) and its distribution and structure were examined with both light and electron microscopy. AH appears as yellow corpuscles which extend as isolated bodies throughout the length of both kidneys in close apposition to the posterior cardinal veins. The yellow corpuscles are composed of convoluted cords of epithelial cells and tortuous sinusoids which empty directly into the cardinal veins. Wide lateral intercellular spaces and accompanying microvilli give the impression of pseudotubules or pseudofollicles to the cords of epithelial cells. The extensive network of tubules of smooth endoplasmic reticulum, the many mitchondria with tubulo‐vesicular cristae, the conspicuous Golgi apparatus, lipid droplets, many pleomorphic granules and the presence of 3β‐HSD are indicative of the steroidogenic nature of the cells. Large, pleomorphic mitochondria and gap junctions are also typical of most cells. The fine structure of the cells in the AH of the reed‐fish most closely resembles that of other Polypteriformes, but the tissue is more widely distributed in the kidneys than in any osteichthylia

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00904.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe branchial circulatory system ofGlossobalanus minutus(Enteropneusta) is investigated by means of transmission electron microscopy. Primary gill bars, or septa, have a single blood vessel longitudinally located along the outer edge of the bar. Secondary gill bars, or tongue bars, show a vessel in their inner, pharyngeal edge. The walls of both vessels are made up of the basement membranes of surrounding epithelia, lacking an endothelium. No definite limits between the vessel lumen and the skeletal rods inside the bars can be seen. Furthermore, the blood seems to penetrate into the rods of both primary and secondary gill bars. In the secondary bars such a phenomenon gives rise to the so‐called ‘lateral vessels’ reported in the light microscopical literature. The significance of these observations is discussed, with special reference to the gill circulatory system of amphioxus, which seems to be strongly similar from a morphological and ultrastructural point of

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00905.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSexually mature adults, embryos and larvae of the pterobranchRhabdopleura normanifrom Bermuda were studied with light and electron microscopy. The sexes are separate among the zooids of a colony, but a given colony may contain females and males. In zooids of either sex the single gonad is associated with a large haemal sinus in the trunk sac and is displaced laterally (to the right or to the left). The wall of the gonad is composed of three layers: an outer metasomal peritoneum, an internal lining of germinal epithelium and an intervening genital haemal sinus. The mature gametes lie in the lumen within the gonad. The spermatozoon is characterized by an elongate nucleus, no obvious acrosome, a long mitochondrial filament in a midpiece appendix and a single flagellum with a 9+2 axoneme. Females brood 200 μm eggs and embryos in their distinctive, basally coiled tubes. The yolky eggs undergo radial cleavage and develop into ciliated, lecithotrophic, oblong larvae (400 μm in length) that are characterized by: (1) yellow coloration peppered with black pigment spots; (2) a deep ventral depression; (3) a posterior adhesive organ; (4) an anterior apical sensory organ; (5) an evenly ciliated epitdermis. The ventral depression is not invaginating endoderm, but is instead a glandular epithelium that evidently secretes the larval cocoon and the adult tube. Internally, the peritoneum of the coelomic cavities begins to split from the periphery of a large, central mass of yolky mesenchyme cells. The larva swims using cilia, but also undergoes contractions, evidently powered by the peritoneal cells, which constitute a myoepithelium. The discussion considers pterobranch affinities with other deuterostomes and with lophophorate

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00906.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSettling and metamorphosing larvae of the pterobranch hemichordateRhabdopleura normanifrom Bermuda were examined with light microscopy, providing the first detailed description of the morphological changes during larval metamorphosis in pterobranchs. The swimming larvae settle within 24 h after being released from the parent tube. The settled larva immediately everts the ventral depression and surrounds itself with a translucent, sealed cocoon. During metamorphosis, which takes place over 7–10 days within the protective cocoon, structural changes occur in the following sequence: (1) differentiation of the oral shield from the anterior region; (2) budding of the two arms from the mid‐dorsal surface; (3) development of the posterior stalk from the adhesive organ; (4) budding of the tentacles on the arms; (5) formation of the pharynx from invaginated ectoderm; (6) formation of the gut and pericardium from the remaining mesenchyme. The gut is the last structure to become functional. The larva relies on stored nutrients throughout metamorphosis. The metamorphosed juvenile builds a tube at an opening in the cocoon and begins to feed. Similarities with lecithotrophic bryozoan and enteropneust larvae are discus

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00907.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe present study probes the occurence of specific components associated with haemocyte surface membranes ofPlanorbarius corneus. The positive response to PHA. anti‐HLADR and other markers are discussed and possible resemblances with the T cells examine

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1988.tb00908.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY