On the evolution and histology of some Cambrian protoconodonts,paraconodonts and primitive euconodonts   总被引：4，自引：0，他引：4  

DONG Xiping Department of Geology  Peking University  Beijing  China  Laboratory of Palaeobiology & Stratigraphy  Nanjing Institute of Ge-ology  Palaeontology  Chinese Academy of Sciences  Nanjing  China 《中国科学D辑(英文版)》2004,47(7):577-584

Although the history of Cambrian conodont study goes back to a century ago, it was not until 1959 that the systematic study of Cambrian conodonts was initi-ated[1]. During the last 44 years Cambrian conodonts have been well documented from all continents but Africa. However, the morphological evolution of para- conodonts and protoconodonts have been subjected to less study than the primitive euconodonts in the inter-val across the Cambrian-Ordovician boundary. Miller (1984) proposed a Weste…  相似文献   

Reproduction of Donax venustus Poli 1795, Donax semistriatus Poli 1795 and Intermediate Morphotypes (Bivalvia: Donacidae) in the Littoral of Málaga (Southern Spain)     

Cristina Tirado  &Carmen Salas 《Marine Ecology》1999,20(2):111-130

The reproduction and sexual cycles of Donax venustus Poli 1795, Donax semistriatus Poli 1795, and individuals with intermediate shell morphotypes were studied in the littoral of Málaga (Southern Spain) from February 1990 to January 1991, using histology and analysing the changes in flesh dry weight. The littoral of Málaga has mild seawater temperatures and several upwellings with high levels of chlorophyll a. Due to these environmental conditions, the reproductive periods of these bivalve species are very extensive, from February to November. The histological study shows asynchronous sexual cycles, with continuous but partial individual spawnings from April to November in about 50% of the D. semistriatus population, and percentages higher than 40% of the sample in most months for D. venustus. An important decrease in the ratio flesh dry weight/length³ was noted from June to August in the three populations; this is apparently related with peaks of spawning. Based on the macroscopic observation of the gonads, on the flesh dry weight study and on histological data, the sexual cycle of the intermediate morphotypes is simultaneous and similar throughout the year with those of D. venustus and D. semistriatus .  相似文献   

东平原狭蚌虫外壳的组织学研究     

任素莲  王德秀 《海洋湖沼通报》1999,(2):32-36

本文对东平原狭蚌虫外壳的组织结构进行了研究。外壳由内外角质层、内外上皮层和皮下结缔组织共同组成。外角质层厚,较规则。上皮细胞有柱状细胞和具有胞突的锥形细胞两种形态。同侧及相对两侧的上皮胞突相连接,构成了许多具有血细胞的血腔隙。  相似文献   

Long bone histology of a eusuchian crocodyliform from the Upper Cretaceous of Spain: Implications for growth strategy in extinct crocodiles     

《Cretaceous Research》2017

The long bone histology of a Late Cretaceous eusuchian crocodyliform from the Iberian Peninsula reveals clear variations in the cortical structure which reflects changes in the speed of bone deposition (i.e., skeletal growth) related to ontogeny. The presence of secondary woven-fibred bone tissue in the perimedullar region of the cortex, and the existence of an external fundamental system in the most external periostic cortex, which is a proxy for somatic maturity and effective cessation of growth, challenges the former idea that the growth strategy of extinct crocodylians fit in the typical ectotherm condition, according to which these animals grew slowly during life under an indeterminate growth strategy. The analysed specimen lived for a minimum of 16 years and the highest preserved apposition rates took place in an advanced ontogenetic stage. The study suggests that the general aspects of the modern crocodylian growth strategy were already in place in some lineages by the Cretaceous.  相似文献   

Histological and Histochemical Analyses of the Cuttlebone Sac of the Golden Cuttlefish Sepia esculenta     

ZHENG Xiaodong XIAO Shu WANG Zhaoping WANG Rucai 《中国海洋大学学报(英文版)》2007,6(4):393-397

The secretion function of mantle is closely related to shell formation in some bivalves and gastropods. Up to now, few researches have been reported for cuttlebone formation in the class Cephalopoda. In this study, the structure and secretion function of cuttlebone sac of the golden cuttlefish Sepia esculenta was analyzed using the histological and histochemical methods. The results showed that high and columnar cells located in sac epithelium, and flat cells existed near the base membrane. A lot of fibroblasts were found in the lateral mantle collective tissue. Some mucus, mucopolysaccharide and alkaline phosphatase (ALP) were found in the sac. The ultrastructural characteristics of Quasi-connective-tissue-calcium cells (QCTCC) were observed using a transmission electron microscope (TEM). The relationship between cuttlebone sac secretion function and shell formation was discussed.  相似文献   

三角帆蚌鳃的组织学研究     

骆大鹏  余祥勇  王梅芳  王佃涛 《广东海洋大学学报》2008,28(3)

对非繁殖期与繁殖前期的雌性三角帆蚌鳃瓣作组织切片,观察其组织形态结构。结果表明,三角帆蚌内、外鳃的鳃丝在组成上是相同的,从外到内,其结构可以分为:上皮、基膜、结缔组织,鳃丝上密布纤毛,鳃丝结缔组织中含吞噬细胞、透明细胞等。外鳃具特有结构——瓣间隔和育儿囊,且在瓣间隔两侧,有发达的小水管系统。由于这种结构的存在,使得内外鳃瓣在鳃瓣厚度、鳃小瓣厚度、鳃丝宽度上存在显著性差异。繁殖前期,内鳃基本无变化,而外鳃发生明显的变化,鳃瓣增厚,鳃腔扩大形成孵化室,为胚胎发育提供一个良好的发育环境。  相似文献   

海湾扇贝外套膜的组织结构与粘液细胞的类型与分布   总被引：4，自引：0，他引：4  

任素莲  傅郁 《中国海洋大学学报(自然科学版)》2006,36(5):739-744

运用HE及AB-PAS染色方法,在光镜下对海湾扇贝(Argopectens irradians)外套膜的组织学结构及粘液细胞的类型与分布进行了观察。结果表明,该部位具有双壳贝类外套膜的典型结构特征,即由中央膜和边缘膜组成,边缘膜具有3个突起,分别为生壳突起、感觉突起和缘膜突起。组织结构主要包括内外上皮层、结缔组织与肌纤维。不同部位外套膜各组织成分的含量与分布有差异。AB-PAS染色反应显示,在上皮层中分布有几种不同类型的粘液细胞,分别为Ⅰ、Ⅱ、Ⅲ、Ⅳ型。Ⅰ型着色为红色,AB阴性,PAS阳性,含中性粘多糖;Ⅱ型为蓝色,AB阳性,PAS阴性,含酸性粘多糖;Ⅲ型染色后呈紫红色,AB,PAS均为阳性,PAS阳性较强,含混和性粘多糖,以中性粘多糖为主;Ⅳ型为蓝紫色,AB,PAS均呈阳性,AB阳性较强,含混和性粘多糖,以酸性粘多糖为主。不同部位粘液细胞的类型与数量均有差异。  相似文献   

方斑东风螺性畸变现象的解剖学和组织学研究   总被引：1，自引：0，他引：1  

于秀娟  朱四喜  沈金辉  陈旭明  黄长江 《台湾海峡》2004,23(4):444-448,i003

以解剖学和组织学方法研究了方斑东风螺未成熟和成熟的正常雌、雄个体以及性畸变个体的生殖系统结构.性畸变个体除具有正常的雌性器官外,还有输精管或阴茎.在正常雄性输精管的个体发育过程中再现了系统发育的过程,而且在性畸变个体输精管的形成过程和发育过程中组织学结构特征的变化与正常雄性输精管的个体发育过程的相似.性畸变雌体的性腺发育受阻.目前,性畸变现象仅存在于成熟个体,但这并不表明未成熟个体中不会发生性畸变现象.具有较高食用价值的方斑东风螺因有机锡污染可能会对人类健康不利,应引起人们的关注.  相似文献   

海马(HIPPOCAMPUS)消化道的解剖学与组织学研究     

蔡仲希 《中国海洋大学学报(自然科学版)》1987,(4)

本文研究了大海马Hippocampus kuda Bleeker,日本海马H·japonicus kauP和三斑海马H.trimacutatue Leach消化道的形态学。三种鱼类消化道的解剖学特点基本相同。消化道均可区分出头肠、前肠、中肠和后肠。中肠最长。口孔小,口腔呈管状,口鳃腔内无齿,无鳃耙,无舌,鳃孔小。不具胃,也无幽门垂,中肠前部稍为扩大形成假胃。 组织学方面共同特点为:粘膜上皮主要由柱状细胞和球形分泌细胞组成。上皮内无多细胞消化腺,未发现味蕾。大海马与日本海马在食道纵褶的形状,球形分泌细胞的分布区,假胃肌层的排列及上皮细胞的形状等方面有种的差别。  相似文献   

Reproductive biology of the mackerel scad Decapterus macarellus from Cabo Verde and the implications for its fishery management     

MPV Costa  DRS Cruz  LS Monteiro  KSM Evora 《African Journal of Marine Science》2020,42(1):35-42

The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals.  相似文献