Pale Type Research Articles

Functional opsin patterning for Drosophila color vision is established through signaling pathways in adjacent object-detection neurons.

Vision is mainly based on two different tasks, object detection and color discrimination, carried out by photoreceptor (PR) cells. The Drosophila compound eye consists of ∼800 ommatidia. Every ommatidium contains eight PR cells, six outer cells (R1-R6) and two inner cells (R7 and R8), by which object detection and color vision are achieved, respectively. Expression of opsin genes in R7 and R8 is highly coordinated through the instructive signal from R7 to R8, and two major ommatidial subtypes are distributed stochastically; pale type expresses Rh3/Rh5 and yellow type expresses Rh4/Rh6 in R7/R8. The homeodomain protein Defective proventriculus (Dve) is expressed in yellow-type R7 and in six outer PRs, and it is involved in Rh3 repression to specify the yellow-type R7. dve mutant eyes exhibited atypical coupling, Rh3/Rh6 and Rh4/Rh5, indicating that Dve activity is required for proper opsin coupling. Surprisingly, Dve activity in R1 is required for the instructive signal, whereas activity in R6 and R7 blocks the signal. Our results indicate that functional coupling of two different neurons is established through signaling pathways from adjacent neurons that are functionally different.

An appressorium membrane protein, Pams1, controls infection structure maturation and virulence via maintaining endosomal stability in the rice blast fungus.

The rice blast fungus Magnaporthe oryzae spores differentiate and mature into functional appressoria by sensing the host surface signals. Environmental stimuli are transduced into cells through internalization during appressorium formation, such as in the cAMP-PKA pathway. Here, we describe a novel contribution to how appressoria mature on the surface of a leaf, and its connection to endosomes and the cAMP-PKA pathway. An appressorium membrane-specific protein, Pams1, is required for maintaining endosomal structure, appressorium maturation, and virulence in M. oryzae. During appressorium development, Pams1 was translocated from the cell membrane to the endosomal membrane. Deletion of PAMS1 led to the formation of two types of abnormal appressoria after 8 h post inoculation (hpi): melanized type I had a reduced virulence, while pale type II was dead. Before 8 hpi, Δpams1 formed appressoria that were similar to those of the wild type. After 8 hpi, the appressoria of Δpams1 was differentiated into two types: (1) the cell walls of type I appressoria were melanized, endosomes were larger, and had a different distribution from the wild type and (2) Type II appressoria gradually stopped melanization and began to die. The organelles, including the nucleus, endosomes, mitochondria, and endoplasmic reticula, were degraded, leaving only autophagic body-like vesicles in type II appressoria. The addition of exogenous cAMP to Δpams1 led to the formation of a greater proportion of type I appressoria and a smaller proportion of type II appressoria. Thus, defects in endosomal structure and the cAMP-PKA pathway are among the causes of the defective appressorium maturation and virulence of Δpams1.

Identification of Genes Involved in the Differentiation of R7y and R7p Photoreceptor Cells in Drosophila.

The R7 and R8 photoreceptor cells of the Drosophila compound eye mediate color vision. Throughout the majority of the eye, these cells occur in two principal types of ommatidia. Approximately 35% of ommatidia are of the pale type and express Rh3 in R7 cells and Rh5 in R8 cells. The remaining 65% are of the yellow type and express Rh4 in R7 cells and Rh6 in R8 cells. The specification of an R8 cell in a pale or yellow ommatidium depends on the fate of the adjacent R7 cell. However, pale and yellow R7 cells are specified by a stochastic process that requires the genes spineless, tango and klumpfuss. To identify additional genes involved in this process we performed genetic screens using a collection of 480 P{EP} transposon insertion strains. We identified genes in gain of function and loss of function screens that significantly altered the percentage of Rh3 expressing R7 cells (Rh3%) from wild-type. 36 strains resulted in altered Rh3% in the gain of function screen where the P{EP} insertion strains were crossed to a sevEP-GAL4 driver line. 53 strains resulted in altered Rh3% in the heterozygous loss of function screen. 4 strains showed effects that differed between the two screens, suggesting that the effect found in the gain of function screen was either larger than, or potentially masked by, the P{EP} insertion alone. Analyses of homozygotes validated many of the candidates identified. These results suggest that R7 cell fate specification is sensitive to perturbations in mRNA transcription, splicing and localization, growth inhibition, post-translational protein modification, cleavage and secretion, hedgehog signaling, ubiquitin protease activity, GTPase activation, actin and cytoskeletal regulation, and Ser/Thr kinase activity, among other diverse signaling and cell biological processes.

Pale Yellow Type IIa Diamond Coloured by H4 Centres

Pale Yellow Type IIa Diamond Coloured by H4 Centres

Development and Morphogenesis of Testis in Human Fetuses

Development and maturation of prenatal testis was studied on 104 human male fetuses. At 9 weeks, the testes were seen as elongated yellowish tissue superolateral to the developing urinary bladder and medial to mesonephros. The testis assumed ellipsoidal shape at 13 weeks. At about 16 weeks, the testes developed convexity on its anterior aspect. Epididymis and testis were at the same level until 20 weeks thereafter the upper testicular pole was encroached upon by the epididymis, with complete encroachment till its anterior aspect at 24 week. The sinus was also distinctly present between the two. The testis assumed miniature adult testis at term, but its size was approximately 1/15th of the adult. Cytoarchitecture of the testis at 9 weeks revealed radially disposed sex cords. At 13 weeks, tunica albuginea,tubular organization in the parenchyma and the Leydig cells were identifiable. At 17 weeks, tunica vasculosa and incomplete lobules were apparent. At 24 weeks, testis was marked by more but solid seminiferous tubules lined by 4–5 germ layers. Leydig cells were also identifiable till 24 weeks. Spermatogenic cells, both pale and dark type were distinguishable although pale spermatogonia were more numerous than dark cells. 28 weeks onwards tunica vaginalis and complete septa in the testicular parenchyma were evident. Moreover, the seminiferous tubules developed central vacuolation. By 30 weeks, seminiferous tubules became more complex as evident by their increase in number and coiled and tortuousity. At term, the fetal testis had not yet attained the cytoarchitecture of the adult testis suggesting that testicular maturation continues postnatally.

Papillary renal cell carcinoma with lipocyte-like cells: A rare morphological variant or an indication of aggressiveness?

Papillary renal cell carcinoma (PRCC) is the second most common carcinoma of the kidney, which is classified into two types. Type 1 displays single layer of cells with scanty pale cytoplasm and type 2 has pseudostratified high-grade nuclei with eosinophilic cytoplasm. Recently, apart from these two types, oncocytic PRCC and clear-cell PRCC have been described. To the best of our knowledge, lipocyte-like cells have not yet been reported to accompany any subtypes of renal cell carcinoma. Herein, we report a case of PRCC with lipocyte-like cells and sarcomatoid features. Lipocyte-like cells might represent a special type of PRCC or this feature may be an indication of poor prognosis regarding its association with sarcomatoid change.

Morphological characterization of the testicular cells and seminiferous epithelium cycle in six species of Neotropical bats

We know little about the process of spermatogenesis in bats, a great and diverse clade of mammals that presents different reproductive strategies. In the present study, spermatogenesis in six species of Neotropical bats was investigated by light microscopy. On the basis of chromatin condensation, nuclear morphology, relative position to the basal membrane and formation of the flagellum, three types of spermatogonia were recognized: dark type A (A(d)), pale type A (A(p)), and type B; the development of spermatids was divided into seven steps. With the exception of Myotis nigricans, the seminiferous epithelium cycle of the other five species studied was similar to those of other mammals, showing gradual stages by the tubular morphology method. Asynchrony was observed in the seminiferous epithelium cycle of M. nigricans, shown by overlapping stages and undefined cycles. The frequencies found in the three phases of the cycle were variable with the greatest frequency occurring in the postmeiotic phase (>50%) and the least in the meiotic phase (<10%). The similarities observed in the five species of Phyllostomidae appeared to be related to their phylogenetic relationship and shorter divergence times, whereas the differences in M. nigricans appeared to be related to its greater phylogenetic distance because the Vespertilionidae family diverged earlier.

Morphological and histochemical characterization of the seminiferous epithelial and Leydig cells of the turkey

Unlike mammals, there is little fundamental information about spermatogenesis in birds. This study was undertaken to clarify the morphology, histochemistry, and lectin affinity of the seminiferous epithelial cells and Leydig cells in pre-pubertal (8- to 15-week old) and adult (40- to 44-week old) domestic turkeys. In adult turkeys, three types of spermatogonia were defined based on their chromatin distribution and nuclear morphology: the dark type A (A d); the pale type A (A p); and the type B. The A d is the least numerous and least conspicuous and consequently difficult to locate. Based on its spatial distribution and overall morphology, type A d spermatogonia were postulated to be the spermatogonia stem cells in the turkey. Antibodies to c-kit were localized to spermatogonia in the pre-pubertal and to a lesser extent in adult males. Peanut agglutinin (PNA) was specific for spermatocytes in the pre-pubertal males and spermatogonia and early spermatocytes in adult males. Wheat-germ agglutinin (WGA) highlighted Sertoli cells in both age groups. Bandeiraea simplicifolia I, soybean agglutinin, and winged-pea agglutinin staining were limited to the wall of the seminiferous tubule and some extra-tubular cell types. Concanavalin A staining was diffuse and not cell-specific and, therefore, could not be used to selectively identify a particular cell type. It was concluded that WGA and PNA could aid in identifying specific cell types in the seminiferous epithelium of testis from pre-pubertal and mature turkeys. Only Leydig cells were alkaline phosphatase reactive in the mature turkey testes. The information from this study is being used to adapt techniques for the isolation and partial purification developed for mammalian spermatogonia to avian spermatogonia and other specific cell types in the testes.

Prepubertal Expansion of Dark and Pale Type A Spermatogonia in the Rhesus Monkey (Macaca mulatta) Results from Proliferation During Infantile and Juvenile Development in a Relatively Gonadotropin Independent Manner1

The purpose of the present study was to determine whether dark and pale type A spermatogonia (Ad and Ap, respectively) are mitotically active during prepubertal development and whether proliferation of these germ cells during this protracted phase of primate development occurs predominantly during infancy before gonadotropin secretion is arrested. Four neonate (1-2 days of age), four infant (4-5 mo of age), and four juvenile (14-17 mo of age) rhesus monkeys (Macaca mulatta) were castrated 2 h after receiving an i.v. bolus of 5-bromo2'-deoxy-uridine (BrdU, 33 mg/kg body weight). Tissue was fixed in Bouin solution, and 5-microm paraffin sections were cut. Using periodic acid-Schiff reagent/Gill hematoxylin staining, the number per testis of Ad and Ap spermatogonia were determined. BrdU S-phase-labeled nuclei were identified using immunofluorescence. Conservative criteria were employed for classifying cell types, and this resulted in a fraction of A spermatogonia remaining unclassified. Ad, Ap, and the unclassified A spermatogonia each showed an approximately 4-fold increase over the 5-mo period from birth to infancy, and a similar increase was observed over the 10-mo period between infancy and the juvenile stage of development. Both Ad and Ap (and unclassified A spermatogonia) exhibited robust and similar S-phase labeling at the three stages of development. We conclude that the prepubertal expansion of Ad and Ap spermatogonia is achieved by mitotic proliferation that is relatively gonadotropin independent. This conclusion raises the question of the nature of the signal that arrests the cell cycle of Ad in adult testis.

Gonadotropin-Independent Proliferation of the Pale Type A Spermatogonia in the Adult Rhesus Monkey (Macaca mulatta)1

The goal of the present study was to examine the relative roles of testosterone (T) and FSH in the proliferation and differentiation of pale type A (Ap) spermatogonia in the rhesus monkey (Macaca mulatta). Twenty adult male monkeys were treated with daily injections of a GnRH-receptor antagonist, acyline, to suppress endogenous gonadotropin secretion during an experiment comprising three phases. Phase 1 established a chronic hypogonadotropic state marked by a profound decrease in testicular size. During phase 2, half the monkeys were implanted with T-filled capsules, and the other half received control implants. Treatment with T produced circulating T levels of approximately 15 ng/ml and normal testicular T content. At the end of phase 2, monkeys were fitted with indwelling i.v. catheters and housed in remote sampling cages for the final phase. During phase 3, five monkeys from the T- and non-T-treated groups were stimulated with recombinant human FSH. The remaining five monkeys from each group received an infusion of vehicle. On the last day of FSH or vehicle infusion, monkeys were bilaterally castrated after receiving an i.v. bolus of bromodeoxyuridine (BrdU). The BrdU labeling of Ap spermatogonia was robust in the hypogonadotropic group and was uninfluenced by treatment with T and FSH, either alone or in combination. In contrast, both T and FSH stimulated spermatogonial differentiation, and this effect was amplified by combined treatment. We conclude that marked Ap spermatogonial proliferation occurs constitutively and in a gonadotropin-independent manner and that differentiation of Ap into B spermatogonia is absolutely gonadotropin dependent and may be driven by either T or FSH.

Vegetative disorders in children with congenital heart diseases of pale type

The tendency to increase the sympathetic tonus in rest in all age groups especially in 4 children under school age and girls in pubertal period is revealed during the investigation of vegetative egulation by the mathematical analysis of the heart rhythm variability in children with congenital heart diseases of pale type.

Germ cell maturation and cellular associations in the seminiferous epithelial cycle of the chimpanzee

Seminiferous tubule architecture, germ cell maturation steps and cellular associations (stages) of the spermatogenic cycle of the chimpanzee ( Pan troglodytes) are resolved. Cross sections of seminiferous tubules usually exhibit 2 to 4 stages, occasionally 1, and rarely 5; stages are not functionally sequential in structurally contiguous regions. The cellular maturation steps are: dark type A stem cell (Ad), pale type A (Ap), type B (B) spermatogonia; resting or preleptotene (Pl), leptotene (L), zygotene (Z), pachytene (P), diplotene (Di) primary spermatocytes; meiotic divisions (M1, M2); secondary spermatocytes (2°S); six developmental stages of the spermatid (Sa, Sb1, Sb2, Sc, Sd1, Sd2) composing spermiogenesis. The germ cell maturation steps characteristic of the six cellular associations (stages I–VI) are: Ad, Ap, B, P, Sa, Sd1 (I); Ad, Ap, B, Pl, P, Sa, Sd2 (II); Ad, Ap, B, Pl, L, P, Sb1 (III); Ad, Ap, Pl, L, P, Sb2 (IV); Ad, Ap, L, Z, P, Di, Sc (V); Ad, Ap, B, Z, P, Di, 2°S, Sc (VI). Surgical pressure trauma causes sloughing of some 2°S spermatocytes and some Sa, Sb1, Sb2, Sd1, and Sd2 spermatids, resulting in missing generations, and disrupts Sertoli cell attachments, affecting germ cell development and associations. In structure and function, chimpanzee spermatogenesis appears most similar to the human.

Some morphological, histological, cytological and histochemical aspects of Reinke's oedema.

Using morphological criteria we divided Reinke's oedema into a pale (transparent) and a livid type. The latter is more difficult to treat because of its prolonged postoperative recovery. Ten samples of pale Reinke's oedema and 10 of livid oedema were selected for cytological, histological and histochemical analysis in order to determine some of their fundamental characteristics and differences. Tissue samples were stained by hemalaun-eosin, Mallory-azan and Paf-Halmi method (specific for visualization of elastic versus collagen fibres). Cytology (May-Grünwald Giemsa) of cellular elements was undertaken by imprint method of the excised oedematous tissue. Also, the silver-staining nuclear organizer regions (Ag NOR) were identified and quantified. We identified intracytoplasmic granula and silver-staining nuclear organizing regions (Ag NOR) in stromal cells of pale type Reinke's oedema. Thus, it may be supposed that smoke irritation provokes higher activity of stromal cells producing a special substance in Reinke's space-resulting finally in Reinke's oedema.

Experimental brain ischaemia: assessment of injury by magnetic resonance spectroscopy and histology*

Phosphorus magnetic resonance spectroscopy (31P-MRS) was made to measure changes in brain high energy phosphate compounds, adenosine triphosphate (ATP) and phosphocreatine (PCr), inorganic phosphorus (Pi) and intracellular pH (pHi) during a prolonged period of incomplete brain ischaemia produced, in anaesthetized dogs, by bilateral carotid occlusion together with haemorrhagic hypotension for intervals of up to 300 min. Mean arterial blood pressure (MABP) was lowered in a stepwise fashion, until signs of metabolic decompensation (as estimated by MRS) occurred. At that point MABP was varied against further evidence of metabolic decompensation in an attempt to maintain a more constant degree of insult. At the end of the ischaemic period MABP was restored and the animals observed during a 3 h recovery period. At the end of the recovery period the brains were perfusion-fixed for histological examination. A semi-quantitative method of histological evaluation was used to determine the degree of histological damage. This permitted assignment of an 'ischaemic score' to the tissue sampled from each animal. Comparisons were then made between the magnitude of this 'ischaemic score' and the changes in metabolic and physiological variables (ATP, PCr, pHi and MABP) as well as an estimator of phosphorylation potential (PCr/Pi), which were all measured during the ischaemic insult. Histological examination showed a wide variety of neuronal alterations, including dark and pale type injury, which correlated directly with the metabolic derangements brought about by ischaemia. The degree of damage determined from this histological assessment correlated best with the duration and degree of change in PCr/Pi, supporting the use of this ratio as a critical index of cellular energy state. In particular there was a strong linear relationship between the degree of leucocyte recruitment and changes in PCr/Pi. To summarize, metabolic changes, determined by MRS, correlate with the degree of histological damage, and in turn, the classical descriptions of acute ischaemic neuronal injury appear to be validated by MRS determinations of metabolic changes during ischaemia.

Substantia nigra damage induced by ischemia in hyperglycemic rats. A light and electron microscopic study.

Preischemic hyperglycemia induced by feeding or glucose infusion worsens the brain damage and the clinical outcome following ischemia of a given duration and density, and characteristically causes postischemic seizure activity. Light microscopy has previously showed that, in the rat, transient hyperglycemia ischemia induced by bilateral carotid occlusion in combination with arterial hypotension causes a uni- or bilateral lesion in the pars reticulata of the substantia nigra. Since this region has a central role in preventing seizure discharges the present study was carried out to determine the ultrastructural characteristics of this lesion. In rats with 10 min of transient hyperglycemic ischemia followed by recirculation for 1 to 18 h, the pars reticulata of the substantia nigra showed signs of status spongiosus, as well as extensive nerve cell alterations. These changes were observed after all recovery periods studied. The spongiotic appearance was mainly caused by swelling of dendrites and, to a lesser degree, by astrocytic swelling. The dendrites were expanded at all recovery times but the severity increased during the later periods of recirculation. These swollen dendrites contained severely expanded mitochondrias and endoplasmic reticulum. The cytoskeletal elements showed disordered lining of microtubules. Two major types of nerve cell alterations were present: a "pale" and a "dark" variety. The pale type was the most frequent cell alteration. It occurred in all experimental groups and at all time points. Redistribution of the nuclear chromatin and of cytoplasmic organelles as well as swelling of the same type as in the dendrites were the essential changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Renewal of spermatogonia in the monkey (Macaca fascicularis).

Populations of different types of spermatogonia and their mitotic activity were analyzed in the monkey Macaca fascicularis: 3 adults aged 5-6 yr and 3 young aged 2-3 mo. Two young and two adult monkeys received injections of 3H-thymidine for radioautographic study of the relationships between Type A spermatogonia: dark Type A (Ad), pale Type A (Ap) and transition Type A (At). In the adult the number of Ad and At spermatogonia did not change significantly throughout the seminiferous epithelium cycle. The number of Ap spermatogonia doubled at Stage VII, and half divided at Stage IX to give rise to B1 spermatogonia. The durations of the seminiferous epithelium cycle and spermatogenesis were estimated as 10.5 days and 42 days respectively. In the young and adult monkeys, some Ap spermatogonia and a lesser number of At spermatogonia were labeled one h after injection of precursor. At longer intervals after injection, the number of labeled At spermatogonia increased significantly, and some Ad as well as Ap spermatogonia were also labeled. These results indicate that Ap spermatogonia are renewal stem cells, and Ad spermatogonia are reserve stem cells. The differences in labeling after isotope exposure suggest that Ap cells may give rise successively to At and Ad cells.

Structural aspects of ischemic brain damage.

The structural changes during cerebal ischemia are reviewed. In the acute phase the neurons may show either pale or dark type of ischemic injury. The former is usually associated with complete ischemia and the structural alterations are fairly inconspicious, while the latter is seen in incomplete ischemia or ischemia with recirculation and is characterized by shrinkage of neurons with extensive mitochondrial swelling and astrocytic edema. Both types of injury may be irreversible, but long post-ischemic period is usually necessary to see the final outcome of the insult, all the more since the neurons may not die until after a free postischemic interval (even with resumed function) of several hours to days. The delayed death is preceded by peculiar proliferation of cytoplasmic membranes before the doomed neurons become shrunken and disintegrate. This "maturation phenomenon" or "delayed neuronal death" is understandably important since it suggests that a longer postischemic interval for therapeutic interventions may exist. Several factors both during and after the ischemic insult can modify the changes and affect the severity of the damager among the most important ones are the degree of lactic acidosis during the ischemic period, as well as the characteristics of the neurons, since excitoxic damage by transmitter substances released by the ischemic insult has been suggested to be responsible for the delayed neuronal death.

Significance of fluid flow for morphology of acute hypoxic-ischaemic brain cell injury.

It has been suggested that the presence or absence of hypoxic fluid flow during ischaemia determines the structural character of the ischaemic nerve cell injury. It is hypothesised that if a flow of fluid irrigates the injured neurons, there will be major shifts of ions and water, with consequent volumetric changes in the tissue and the 'dark' type of neuronal injury will result; otherwise, the structural changes are less striking and are designated as the 'pale' type. To test this hypothesis, rats were subjected to a global cerebral insult by filling the vasculature with a plasma substitute, which was either left stagnant or was flowing, and was either oxygenated (hypoxic flow) or nitrogenated (anoxic flow). Light and electron microscopy of the brain following 10 to 60 min of hypoxic or anoxic ischaemia disclosed that, under all three circumstances, the predominant nerve cell injury was of the pale type. The results indicate that some additional factors present in whole blood (but not in the plasma substitute) are needed during or after the insult to induce in quantity the dark type of ischaemic nerve cell injury.

Evolution ultrastructurale des cellules germinales foetales jusqu'aux spermatogonies adultes chez le singe Macaca fascicularis

Ultrastructural changes in the spermatogonial line of the macaque, Macaca fascicularis, were studied during foetal development (from day 37), childhood and puberty. The different cell types and their distinctive morphological characteristics have been identified by studying adjacent thick and thin sections under light and electron microscopy. The main criteria used were: organization of the rough endoplasmic reticulum (RER) and its relation to mitochondria, chromatin distribution, stainability and perichromatin granule content, nucleolar organization and differentiation of the nuclear membrane including the lamina and nuclear vacuoles or cisternae. According to their ultrastructure, the following main cell classes were distinguished: gonocytes (37 to 43-day foetuses), prespermatogonia (50 to 110-day foetuses), pale type A (Ap) and dark type A (Ad) adult-type spermatogonia which differentiated progressively in 120 to 140-day foetuses. During childhood, the testis contained only Ap and Ad spermatogonia. At the onset of meiosis (about 48 months after birth), type B spermatogonia appeared, and the different classes of spermatogonia were found lying directly on the basal lamina of the sex cords. The filiation of the spermatogonial line during development has been discussed.

Morphological characteristics of the spermatogonial stem cells in man.

The present investigation is concerned with establishing morphological criteria of spermatogonial stem cells in man. Testicular biopsies from patients having undergone semicastration for malignant tumors and radio- and chemotherapy for one year following the operation were studied light and electron microscopically. Those spermatogonial types that survived the treatment were regarded as stem cells in view of the fact that the stem cells, in contrast to the more differentiated spermatogonia, are radiation resistant and less sensitive to various noxious agents. In 7 out of 28 cases examined, a small number of spermatogonia was found adjacent to the basement membrane. The majority of these cells show the characteristic features of pale type A spermatogonia, while a few cells may represent variants of this cell type. The dark type A spermatogonia are almost completely eliminated from the seminiferous tubules. A concept is proposed that the stem cells of the human testis may be derived from the pale type A spermatogonia or the variants of this cell type.