The effect of change of background colour on the ultrastructure of the pars intermedia of the pituitary of the eel (Anguilla anguilla)

Summary Colour change in the eel resulted in marked ultrastructural changes in the pre-dominating (Type II) secretory cells of the pars intermedia of the pituitary. The effects on these cells of transferring eels from white to black backgrounds for periods of up to 56 days were: a) hypertrophy of the rough endoplasmic reticulum, which increased from 12 to 35% of the cytoplasmic volume; b) loss of secretory granules which decreased from 38 to 5% of the cytoplasmic volume; c) development of a system of fine (25–35 nm) tubules located especially at the secretory poles of the cells but also found in the region of the Golgi apparatus. The tubules were seen to connect with the plasma membrane, with the limiting membrane of the secretory granules, and in one instance to connect a granule with the plasma membrane. After glutaraldehyde fixation at pH 5, electron dense material similar to that found in the secretory granules was observed in the lumen of many of the tubules.The changes that occurred in black background eels are taken to indicate that the Type II cells of the pars intermedia are responsible for MSH secretion, particularly since these changes were reversed by returning eels to white backgrounds. The cytoplasmic tubules found in Type II cells may indicate a process for MSH release which does not involve granule extrusion, but rather direct transport of material from the Golgi apparatus to the cell membrane.The electron microscope facilities used in this investigation were funded by the Medical Research Council.     

Innervation de l'hypophyse intermédiaire deRana esculenta,et identification des fibres aminergiques par autoradiographie au microscope électronique

Résumé L'hypophyse intermédiaire deRana esculenta, se compose de deux zones distinctes: une zone externe formée de cellules glandulaires d'aspect normal, une zone interne constituée de cellules à globules.Son innervation est assurée par un faisceau d'axones d'origine hypothalamique qui se subdivise dans l'angle rostro-ventral en deux groupes de fibres distinctes. Le premier groupe se termine sur les capillaires de cette zone, les fibres du deuxième groupe se terminent au contact des cellules glandulaires. Elles sont nombreuses dans la zone interne, moins abondantes dans la zone externe. D'après leurs caractères morphologiques et cytologiques, on distingue 3 types de fibres: des axones neurosécréteurs à grains d'environ 1000 à 1800 Å de diamètre (type 1), des terminaisons à grains de 550 à 950 Å de diamètre (type 2) et des terminaisons pratiquement dépourvues de grains (type 3).Après l'injection de DL noradrénaline H³ et étude autoradiographique au microscope électronique, les terminaisons de type 2 à fines granulations se marquent intensément tandis que les fibres du type 1 et du type 3 ne présentent pas de marquage. Cette méthode met en évidence les fibres aminergiques dont le rôle est discuté.

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Innervation of thePars intermedia ofRana esculenta and identification of aminergic fibres by autoradiography in electron microscopy

Summary In thepars intermedia ofRana esculenta, two zones may be distinguished: an external zone with normal glandular cells and an internal zone with large globular cells.The innervation is assumed by a hypothalamic nervous tract which divides in two distinct bundles: The first group of terminals innervates the capillaries in the rostro-ventral corner of thepars intermedia. The second one penetrates the glandular parenchyma where they are numerous in the internal zone and less numerous in the external zone.On the basis of their morphological and cytological characteristics three kinds of fibres are distinguished: neurosecretory axones with granules of about 1,000 to 1,800 Å in diameter (type 1) terminals with fine granules of 550 to 950 Å, (type 2) and terminals without granules (type 3).After injection of DL noradrenaline H³ and autoradiography on electron microscopy, the type 2 terminals with fine granules are strongly labeled while type 1 and type 3 fibres are devoid of labeling. The fixation of DL noradrenaline H³ demonstrates the aminergic fibres the function of which is discussed.

Avec la collaboration technique de Mme Y. Rohr et de M. C. Chevalier.     

Embryonic development and secretory differentiation in the pars tuberalis of the mouse hypophysis

Summary The pars tuberalis (PT) of the mouse, like that of other mammals, consists mainly of glandular cells rich in glycogen and peculiar to this lobe. In the mouse, the glandular cells are characterized by large, dense secretory vesicles (up to 300 nm in diameter), the abundance of which indicates a marked secretory activity. The PT develops from a distinct antero-ventral area of Rathke's pouch. The border between the anlagen of the PT and the pars distalis is formed by Atwell's recessus which represents the access for the vessels afferent to the pars distalis. The pedicle of Rathke's pouch is incorporated into the PT anlage, thus contributing to its formation. The entire PT anlage is characterized by glycogen accumulation from the commencement of its formation and persisting in the adult tuberal lobe. Secretory differentiation of the glandular cells of the PT occurs at day 12 of gestation, preceding that of all other adenohypophysial cell types. The secretory features of these cells (development of ergastoplasm and Golgi apparatus, abundance of dense secretory vesicles) appear at an early stage of the embryonic life (14 days) comparable to those of mature cells. These results confirm earlier observations in the foetal rat where hypophysial secretion also begins in the PT. The existence of peculiar glandular cells speaks in favour of a specific but still unknown function of the PT during foetal and adult life.This work is dedicated to Professor F. Stutinsky     

On the identity of the thyrotropic cell in the red-spotted newt

Summary Although the pars distalis of the red-spotted newt has previously undergone extensive cytological examination, the identity of its thyrotropic cells has remained uncertain. From the present ultrastructural study, cells of type 3 (Masur, 1969) containing granules 150–180 nm in diameter are concluded to be the thyrotropes. Such cells were found to be present in the regions of the pars distalis where thyroidectomy cells arise after ablation of the thyroid gland. Cells of type 3 are probably identical with a population of cells containing granules which stain with silver methenamine indicating the presence of a glycoprotein such as thyroid stimulating hormone (TSH). Thyroidectomy cells containing a few residual granules 150–180 nm in diameter were occasionally found in partes distales from newts killed 3 or 7 days after ablation of the thyroid gland, and were abundant in pituitaries 21 days after thyroidectomy. Only cells of type 3 responded (by vacuolation of granules) when animals were immersed in water containing 10 g/l of thyroxine. No cells of the pars distalis showed cytological change after administration of synthetic thyrotropic releasing hormone (TRH) giving additional support to the view that this hormone has no stimulatory role in amphibians.Work supported in part by research grant 1 R01 AM 16731-01 from the Institute of Arthritis, Metabolism and Metabolic Diseases and in part by grant PCM 75-17637 from the National Science Foundation     

Permeability of the amphibian pars intermedia to peroxidase injected intravascularly

To study the penetration of protein from the blood into and through the pars intermedia of anurans, the electron-dense tracer, horseradish peroxidase (HRP), was injected into the vascular system of the frog, Rana pipiens. Pinocytotic vesicles were seen along plasma membranes of the stellate cells abutting the pericapillary spaces between the pars intermedia and pars nervosa. The HRP was seen within both the pericapillary spaces and these pinocytotic vesicles. In addition, the HRP was very prominent in the extracellular spaces between adjacent stellate and/or MSH cells and around nerve endings and thus, appeared to move from the vascular spaces and into the interior of the pars intermedia. Therefore, the poorly vascularized pars intermedia may have such a route for transfer of materials throughout the gland.     

Ultrastructure of STH cells of the pars distalis of castrated male mice after hepatectomy

Summary An electron microscopic study aimed at differentiation between castration gonadotrophs and posthepatectomy STH cells was performed on the pars distalis of the pituitary of castrated male mice, after partial hepatectomy. The ultrastructural features observed permit the distinction of both cell types. In the present experiments some remarkable ultrastructural changes, other than those described in a previous report, have been found in STH cells of hepatectomized mice with or without previous castration. Most of them contained masses of heterogeneous electron density, suggesting fusion of granules. These masses and some secretion granules were observed close to the plasma membrane, apparently in the process of discharging material into the pericapillary space. Granular extrusion was more frequent than normally. An increased number of lysosomes, probably related to the digestion of overproduced secretion material, was evident. The appearance of concentric lamellar formations might be related to an increase in cell movements. STH cells with severe cytoplasmic damage were also found, indicating an increased rate of cell loss.Work carried out with the financial assistance by a grant from the Comisión de Investigación Científica de la Universidad Nacional de La Plata. Thanks are due to the members of the Technical Staff of the Institute for their technical assistance.     

Specification and development of the pars intercerebralis and pars lateralis, neuroendocrine command centers in the Drosophila brain

The central neuroendocrine system in the Drosophila brain includes two centers, the pars intercerebralis (PI) and pars lateralis (PL). The PI and PL contain neurosecretory cells (NSCs) which project their axons to the ring gland, a complex of peripheral endocrine glands flanking the aorta. We present here a developmental and genetic study of the PI and PL. The PI and PL are derived from adjacent neurectodermal placodes in the dorso-medial head. The placodes invaginate during late embryogenesis and become attached to the brain primordium. The PI placode and its derivatives express the homeobox gene Dchx1 and can be followed until the late pupal stage. NSCs labeled by the expression of Drosophila insulin-like peptide (Dilp), FMRF, and myomodulin form part of the Dchx1 expressing PI domain. NSCs of the PL can be followed throughout development by their expression of the adhesion molecule FasII. Decapentaplegic (Dpp), secreted along the dorsal midline of the early embryo, inhibits the formation of the PI and PL placodes; loss of the signal results in an unpaired, enlarged placodeal ectoderm. The other early activated signaling pathway, EGFR, is positively required for the maintenance of the PI placode. Of the dorso-medially expressed head gap genes, only tailless (tll) is required for the specification of the PI. Absence of the corpora cardiaca, the endocrine gland innervated by neurosecretory cells of the PI and PL, does not affect the formation of the PI/PL, indicating that inductive stimuli from their target tissue are not essential for early PI/PL development.     

康柏西普预防严重后巩膜裂伤玻璃体切除术后增生性玻璃体视网膜病变的临床疗效

摘要 目的：探讨玻璃体腔注射康柏西普对于严重后巩膜裂伤患者玻璃体切除术后增生性玻璃体视网膜病变发生的预防效果。方法：选取从2018年9月至2020年9月我院收治的40例（40眼）严重后巩膜裂伤患者进行研究,随机分为对照组20眼（行常规巩膜裂伤缝合术及经睫状体平坦部玻璃体切除术）和观察组20眼（行巩膜裂伤缝合术及经睫状体平坦部玻璃体切除术的同时联合玻璃体腔注射康柏西普治疗）。比较两组患者术前及术后的视力、眼压,以及术后增生性玻璃体视网膜病变的发生率、视网膜再脱离的发生率。结果：对照组及观察组术后的最佳矫正视力较术前均提高、术后眼压均正常,观察组术后的增生性玻璃体视网膜病变发生率（15.0 %）明显低于对照组（45.0 %, P<0.05）,观察组术后视网膜脱离复发率（5.0 %）低于对照组（30.0 %, P>0.05）。结论：严重后巩膜裂伤患者玻璃体切除术联合玻璃体注射康柏西普治疗能够有效降低增生性玻璃体视网膜病变的发生率和术后视网膜脱离的复发率,还可以改善患者的视力预后。     

Cytological changes in the pars distalis of pituitary of the green frog,Rana esculenta L., during the reproductive cycle

Summary The cytological changes in the pars distalis of pituitary of male and female green frog, Rana esculenta during the reproductive cycle have been studied by examining the form, cytoplasmic granulation and numerical proportions of the different cell types. Some sex differences were recorded, particularly in relative total number of cells in a median sagittal section of the pars distalis. No extensive cytological changes occur during the hibernation period, but there are striking alterations at the time of spring awakening, during spawning months and during replenishment of the spent gonads i.e. during late summer and autumn months. Important changes are to be observed in the acidophils type one (A1) and basophils type two (B2) and three (B3). Changes in the A1 cells during breeding season have been speculated as being in support of the spawning activity of the animal. The B2 cells exhibit most profound changes which correlate precisely with the morphological changes in gonads, and these cells are considered as the FSH-gonadotrops. The functional significance of the B3 cells is discussed and it is suggested that they might be the source of an ICSH- or LH-like hormone.The work has been supported by grant from the National Research Council of Italy.The award of postdoctoral fellowship by the National Research Council of Italy is gratefully acknowledged.