Immunohistochemically detected ontogeny of prolactin and growth hormone cells in the African catfish Clarias gariepinus

The chronological appearance of selected endocrine cells in the pituitary of African catfish Clarias gariepinus (Burchell, 1822) was studied morphologically, histologically and immunohistochemically by using antisera raised against catfish growth hormone (cgGH) and recombinant tilapia prolactin I (tPRL). cgGH- and tPRL-like immunoreactive cells were visible from day 1 post fertilisation (hatching) throughout the juvenile and the adult stage. From 1 to 90 days after hatching, the larval pituitary is oval in shape with a distinctly shaped rostral pars distalis, proximal pars distalis and pars intermedia. From day 120 onwards allometric growth of the rostral and proximal pars distalis extended the prolactin and growth hormone cells anteriorily and posteriorily, respectively. Size and activity of the prolactin and growth hormone cells, measured by the ratio of cell surface to nuclear surface remained constant until day 40 and showed a growth spurt thereafter. Growth hormone content, measured with a catfish-specific radio-immunoassay from hatching until 60 h post hatching, increased exponentially between 30 and 60 h.     

Development of serotonergic neurons in the brain of the mackerel, Scomber scombrus. An immunohistochemical study

The ontogenetic development of serotonin immunoreactivity (5-HTir) neurons was investigated by immunocytochemistry in the brain of the mackerel, from fertilization to the complete resorption of the yolk sac (201 h). 5-HTir appears first in cell bodies in the diencephalon, on both sides of the third ventricle. At hatching time 5-HTir perikarya are also present in the mesencephalon and the inferior raphe but in small numbers. During larval stages, immunoreactivity appears consecutively in the area thalamo piaetectalis, the nuclei raphe pallidus and obscurus, the nuclei tegmenti dorsalis lateralis, recessus posterioris, lateralis hypothalami and paragigantocellularis lateralis. These results, together with previous findings, suggest a common pattern of distribution of the different 5-HTir neuronal populations in the brain of a teleost during ontogeny but a different sequence of appearance of initial 5-HTir in these populations between species.     

Differential release of prostaglandins by organ cultures of human fetal trachea and lung

Summary Human fetal lung at 16–19 weeks gestation has a partially differentiated epithelium, and in organ culture, distal airsacs dilate and the epithelium autodifferentiates to type I and II pneumatocytes, processes regulated by endogenous prostaglandin PGE₂. Human fetal trachea, at the same gestation, has a terminally differentiated mucociliary epithelium but after 4–6 d in organ culture, develops squamous metaplasia. Tracheal cultures restricted to 3 d have normal phase-contrast and light microscopy appearances and immunohistochemical reactivities (epithelium: cytokeratin 7,8,18; glutathione S-transferase pi-isozyme; epithelial membrane antigen and mesenchyme; desmin; vimentin). In human fetal trachea organ cultures, the predominant prostaglandins released are 6-keto-PGF_1α, PGF_2α, and PGE₂, a pattern similar to that previously described for human adult trachea and lung. In fetal lung cultures, 13,14-dihydro-15-keto-PGF_2α is the major prostaglandin released with lesser amounts of 13,14-dihydro-15-keto-PFG_2α, PGF_2α, PGE₂, and 6-keto-PGF_1α. Human fetal lungin vitro has the competence to self-differentiate, as early as 12 weeks gestation and presence of high levels in fetal lung of the inactive metabolite 13,14-dihydro-15-keto-PGE₂ relative to PGE₂ suggests that active prostaglandin catabolism may be one of the mechanisms to retard this stage of maturationin vivo by limiting PGE₂ availability. Surprisingly, the profile of prostaglandins released from fetal lung organ culture does not change to that of a mature lung with terminal differentiation of the epithelium, and this may indicate differences in the expression of key prostaglandin-metabolizing enzymes in developing human fetal lung in culture and within utero ontogeny.     

Ontogeny of gonadal sex development relative to growth in fathead minnow

Ovarian differentiation of fathead minnow Pimephales promelas occurred at between 10 and 25 days post‐hatch (dph)(8–11 mm fork length, L _F, and 7–12 mg), and was characterized by the presence of meiotic cells in the centre of the gonad, location of the somatic cells at the periphery of the gonad and the formation of an ovarian cavity. In contrast with the developing ovary, in the presumptive testis somatic cells were scattered throughout the gonads and this was evident from 25 dph (fish >10 mm and >11 mg). In males, at 60 dph (15–26 mm and 39–220 mg) the efferent ducts (sperm ducts) were apparent and the testis lobules started to form, but germ cells (spermatogonia) did not enter meiosis until between 90 and 120 dph. Fish of both sexes reached full sexual maturity at between 120 and 150 dph (males: 33–59 mm and 400–2895 mg; females: 24–48 mm and 160–1464 mg). Differences in body size ( L _F and mass) between males and females were only apparent when the fish were approaching full sexual maturity (120 dph).     

Topographical and ontogenetic study of the neurons producing growth hormone-releasing factor in human hypothalamus

Neurons producing growth hormone-releasing factor have been characterized and analyzed by immunohistochemistry in the hypothalami of human fetuses, neonates, infants and adults, using two antibodies against human pancreatic GRF (hpGRF). One of the antibodies recognized both the hpGRF(1-40)OH and hpGRF(1-44)NH2 in the mid portion (between the 28th and 39th amino acid), the other one specifically recognized the C-terminal end of hpGRF(1-44)NH2. These two antibodies stain a single neuronal system with cell bodies mainly located in the infundibular (arcuate) nucleus, and in the ventromedial and lateralis tuber nuclei. These neurons project to the median eminence where they give numerous endings in contact with portal vessels. These neurons are distinct from those containing LH-RH, somatostatin, CRF or pro-opiocortin. In fetuses, neurons immunoreactive with hpGRF antibodies are first detected at the 29th week. They display a neuroblastic aspect which persists after birth. Immunoreactive fibers are detectable in the median eminence after the 31st week. These results demonstrate that the infundibular nucleus plays a major role in control of GH secretion in man and that secretion of GRF appears late during fetal life; this suggests that the first stages of differentiation and development of GH producing cells in the human fetus do not depend on hypothalamic GRF secretion.     

Endocrine cells in atresic chick embryo intestine: histochemical and immunohistochemical study

Intestinal motility disorders are an important problem in the postoperative management of patients with intestinal atresia. Intestinal motility could be initiated by luminal factors that activate intrinsic and extrinsic primary afferent nerves involved in the peristaltic reflex. Endocrine cells act as a key point, because they transfer information regarding the intestinal contents and intraluminal pressure to nerve fibers lying in close proximity to the basolateral surface of the epithelium. In chick embryo, experimental intestinal atresia is associated with disorders in the development of the enteric nervous system, related to the severity of intestinal dilation. Our aim was to investigate the distribution pattern of endocrine cells in the developing endocrine system of chick embryo small intestine with experimentally-induced atresia on day 12 and on day 16. Changes in enteroendocrine population were examined in gut specimens (excised proximal and distal to the atresia) from experimental embryos 19 days old and in control sham-operated chick embryos at the same age. Sections from proximal and distal bowel and control bowel were stained with Grimelius silver stain, a valuable histochemical method for detecting the argyrophil and argentophilic cells, and with an immunohistochemical procedure for detecting serotonin and neurotensin immunoreactive cells. In chick embryo proximal bowel, intestinal dilation differed in the various embryos. We found significantly higher enteroendocrine cell counts in proximal bowel than in distal and control bowel. The differences depended on the precociousness of surgery and the severity of dilation. Considering the major contribution of enteroendocrine cells to the peristaltic reflex, our data may help to explain the pathogenesis of motility disorders related to intestinal atresia.     

分化抑制因子在免疫细胞发育及血液恶性肿瘤发生中的调控作用

分化抑制因子(inhibitor of differentiation, Id)属于螺旋-环-螺旋蛋白家族成员,通过与其他HLH蛋白质形成异源二聚体而发挥转录负调控作用,抑制基因的表达。Id可促进细胞的增殖,抑制细胞分化。尤其在多种免疫细胞的发育和分化过程中,Id发挥着必不可少的作用。本篇综述主要介绍了近年来关于Id家族各成员在先天性和适应性免疫系统中如何调控多种细胞谱系的产生及命运决定的最新研究进展。Id通过与E蛋白等不同的转录因子相互作用,在自然杀伤细胞、先天性淋巴细胞、T细胞和B细胞等的分化过程中具有多种多样的功能,确保了免疫细胞在各免疫器官中发育的有序进行。另一方面,Id基因的异常表达及功能失衡与血液系统恶性肿瘤的发生和进展程度密切相关。在从白血病到恶性淋巴瘤的不同血液肿瘤中,Id可作为促癌或抑癌因子发挥多样的作用。因此,Id可作为血液肿瘤诊断及预后的标记基因,并有望成为肿瘤治疗的重要靶标。     

From the cholinergic gene locus to the cholinergic neuron

The cholinergic gene locus (CGL) was first identified in 1994 as the site (human chromosome 10q11.2) at which choline acetyltransferase and a functional vesicular acetylcholine transporter are co-localized. Here, we present recent neuroanatomical, developmental, and evolutionary insights into the chemical coding of cholinergic neurotransmission that have been gleaned from the study of the CGL, and its protein products VAChT and ChAT, which comprise a synthesis-sequestration pathway that functionally defines the cholinergic phenotype.

Résumé

Le locus génétique cholinergique (cholinergic gene locus, CGL) a été identifié en 1994 et regroupe les gènes de la choline acétyltransférase et d'un récepteur vésiculaire d'acétylcholine (chromosome humain 10q11.2). Nous présentons ici des données sur la neuroanatomie, le développement et l'évolution de la neurotransmission cholinergique obtenus à partir de l'étude du CGL et de ses produits protéiques, VAChT et ChAT: ce système de synthèse-séquestration définit fonctionnellement le phénotype cholinergique.     

中国黄蚜小蜂属一新记录种及其蛹的个体发育

记述了中国黄蚜小蜂属一新记录种—桑氏黄蚜小蜂 Aphytis sankarani Rosen et DeBach,描述了桑氏黄蚜小蜂的形态特征,观察了蛹的个体发育,并提供了重要鉴别特征的照片。